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Zcash

2019-12-24T16:02:45Z

Retimuko: Undid revision 932257395 by 37.173.131.32 (talk) independent reliable sources please

{{about-distinguish|the cryptocurrency Zcash|Zerocoin|zcache}}
{{Use dmy dates|date=February 2016}}
{{Infobox cryptocurrency
| symbol =
| ticker_symbol = ZEC
| currency_name = Zcash
| image_1 = Zcash logo 2019.svg
| image_2 =
| image_title_1 =
| precision =
| white_paper = [https://raw.githubusercontent.com/zcash/zips/master/protocol/protocol.pdf "Zcash Protocol Specification"]
| implementations =
| initial_release_version =
| initial_release_date = {{Start date and age|df=yes|2016|10|28}}
| iso_code = ZEC{{efn|Unofficial.|group=infobox}}
| block_reward = 12.5 ZEC <ref name="FAQs" />
| circulating_supply = 7,756,969 <ref name="zchain">{{cite web|url=https://explorer.zcha.in/|accessdate=1 November 2019|title=Zchain - Zcash Blockchain Explorer & API}}</ref>
| supply_limit = 21,000,000 <ref name="FAQs">{{cite web|url=https://z.cash/support/faq/#zcash-economics|accessdate=10 July 2019|title=Frequently Asked Questions - Zcash}}</ref>
| exchange_rate = $37.65 <ref name="coinbase">{{cite web|url=https://www.coinbase.com/price/zcash|accessdate=10 July 2019|title=Zcash Price Chart (ZEC) - Coinbase}}</ref><ref name="zchain" />
| market_cap = $292.04 million <ref name="coinbase" /><ref name="zchain" />
| footnotes = {{notelist|group=infobox}}
| status = Active
| latest_release_version = 2.1.0
| latest_release_date = {{Start date and age|df=yes|2019|11|04}} <ref>{{cite web|url=https://github.com/zcash/zcash/releases|accessdate=9 November 2019|title=Releases - zcash/zcash|via=[[GitHub]]}}</ref>
| project_fork_of =
| programming_languages =
| split_date =
| split_from =
| hash_function = [[Equihash]]
| issuance_schedule =
| timestamping =
| merged_mining_parent =
| block_time = 2.5 minutes <ref name="FAQs" /><ref name="zchain" />
| operating_system =
| author =
| developer =
| source_model =
| license =
| website = {{URL|https://z.cash}}
| block_explorer = {{URL|https://explorer.zcha.in/}}
| ledger_start =
| code_repository = {{URL|https://github.com/zcash/zcash}}
}}
'''Zcash''' is a [[cryptocurrency]] aimed at using [[cryptography]] to provide enhanced privacy for its users compared to other cryptocurrencies such as [[Bitcoin]].

Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref name=NYT>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times}}</ref>

Transactions can be "transparent" and similar to bitcoin transactions in which case they are controlled by a t-addr, or can be a type of [[zero-knowledge proof]] called [[Non-interactive zero-knowledge proof|zk-SNARK]]s; the transactions are then said to be "shielded" and are controlled by a z-addr. Zcash coins are either in a transparent pool or a shielded pool; as of December 2017 only around 4% of Zcash coins were in the shielded pool and at that time most wallet programs did not support z-addrs and no web-based wallets supported them.<ref name=quesnelle>{{cite arXiv|last=Quesnelle|first=Jeffrey|eprint=1712.01210|title=On the linkability of Zcash transactions|class=cs.CR|date=2017}}</ref>

Zcash affords private transactors the option of "selective disclosure", allowing a user to prove payment for auditing purposes. One such reason is to allow private transactors the choice to comply with anti-money laundering or tax regulations. "Transactions are auditable but disclosure is under the participant's control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=31 October 2016|language=en}}</ref> The company has hosted virtual meetings with law enforcement agencies around the U.S. to explain these fundamentals and has gone on the record of saying that "they did not develop the currency to facilitate illegal activity".<ref name=NYT/>

== See also ==
* [[Legality of bitcoin by country]]
*[[Zerocoin protocol]]
* [[SNARK|zk-SNARKs]]

== References ==
{{Reflist}}

==External links==
* [https://z.cash/ Official website]
* [https://www.zfnd.org/ Zcash Foundation]

{{Cryptocurrencies|state=expanded}}
{{Authority control}}

{{Portal bar|Economics|Free and open-source software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]
[[Category:Computer-related introductions in 2016]]

Zstandard

2019-10-14T20:57:31Z

Retimuko: Undid revision 921263449 by 212.90.61.189 (talk) no blogs please

{{short description|Lossless compression algorithm}}
{{primary sources|date=September 2017}}
{{Infobox software
| name = Zstandard
| author = Yann Collet
| developer = Yann Collet, Przemysław Skibiński ([https://github.com/facebook/zstd/graphs/contributors inikep])
| operating system = [[Cross-platform]]
| genre = [[Data compression]]
| programming language = [[C (programming language)|C]]
| license = Dual: [[BSD License]] + GPLv2
| title =
| logo = Zstandard logo.png
| released = {{Start date|2015|01|23|df=y}}
| discontinued =
| latest release version = 1.4.2
| latest release date = {{Start date and age|2019|7|25|df=y}}<ref>{{cite web|url=https://github.com/facebook/zstd/releases/|accessdate=19 July 2018|title=Releases - facebook/zstd|via=[[GitHub]]}}</ref>
| latest preview version =
| platform = Portable
| size =
}}

'''Zstandard''' (or '''zstd''') is a [[lossless compression|lossless]] [[data compression]] algorithm developed by [[Yann Collet]] at [[Facebook]].
''Zstd'' is the reference implementation in [[C (programming language)|C]]. Version 1 of this implementation was released as [[free software]] on {{date|2016-08-31}}.<ref>
{{cite news
|author=Sergio De Simone
|url=https://www.infoq.com/news/2016/09/facebook-zstandard-compression
|title=Facebook Open-Sources New Compression Algorithm Outperforming Zlib
|publisher=InfoQ
|accessdate=2019-04-20
|date=2016-09-02}}
</ref><ref>{{cite news
|url=https://www.theregister.co.uk/2016/08/31/facebook_open_source_database/
|date=2016-08-31
|publisher=The Register
|accessdate=2016-09-06
|title=Life imitates satire: Facebook touts zlib killer just like Silicon Valley's Pied Piper}}
</ref>

==Features==
Zstandard was designed to give a compression ratio comparable to that of the [[DEFLATE]] algorithm (developed in 1991 and used in the original [[zip (file format)|ZIP]] and [[gzip]] programs), but faster, especially for decompression. It is tunable with compression levels ranging from negative 5 (fastest)<ref>https://github.com/facebook/zstd/releases/tag/v1.3.4 Faster compression levels</ref> to 22 (slowest in compression speed, but best compression ratio).

The zstd package includes parallel (multi-threaded) implementations of both compression and decompression. Starting from version 1.3.2 (October 2017), zstd optionally implements very long range search and deduplication similar to [[rzip]] or [[lrzip]].

Compression speed can vary by a factor of 20 or more between the fastest and slowest levels, while decompression is uniformly fast, varying by less than 20% between the fastest and slowest levels.<ref name=openzfs>
{{cite web
|url=http://www.open-zfs.org/w/images/b/b3/03-OpenZFS_2017_-_ZStandard_in_ZFS.pdf
|title=ZStandard in ZFS
|date=2017
|accessdate=2019-04-20
|website=open-zfs.org
|format=PDF
}}</ref>

''Zstd'' at its maximum compression level gives a compression ratio close to [[Lempel–Ziv–Markov chain algorithm|lzma]],
[[Lempel–Ziv–Markov chain algorithm#LZHAM|lzham]], and [[Prediction by partial matching#PPMX|ppmx]], and performs better than [[LHA (file format)|lza]], or [[bzip2]].<ref>
{{cite web
|url=http://mattmahoney.net/dc/silesia.html
|title=Silesia Open Source Compression Benchmark
|author=Matt Mahoney
|accessdate=2019-05-10}}</ref><ref>
{{cite web
|url=http://mattmahoney.net/dc/text.html
|title=Large Text Compression Benchmark, .2157 zstd
|author=Matt Mahoney
|date=2016-08-29
|accessdate=2016-09-01}}
</ref> Zstandard reaches the current [[Pareto efficiency|Pareto frontier]], as it decompresses faster than any other currently-available algorithm with similar or better compression ratio.<ref name="web-compression">
{{citation
|title=TurboBench: Static/Dynamic web content compression benchmark
|url=https://sites.google.com/site/powturbo/home/web-compression
|publisher=PowTurbo}}
</ref><ref name="silesia-benchmark">
{{citation
|author=Matt Mahoney
|title=Silesia Open Source Compression Benchmark
|url=http://mattmahoney.net/dc/silesia.html}}
</ref>

Dictionaries can have a large impact on the compression ratio of small files, so Zstandard can use a user-provided compression dictionary. It also offers a training mode, able to generate a dictionary from a set of samples.<ref>
{{cite web
|url=https://indico.fnal.gov/event/15154/contribution/5/material/slides/0.pdf
|title=Facebook developers report massive speedups and compression ratio improvements when using dictionaries}}
</ref><ref>
{{cite web
|url=https://code.facebook.com/posts/1658392934479273/smaller-and-faster-data-compression-with-zstandard/
|title=Smaller and faster data compression with Zstandard
|date=31 August 2016
|publisher=Facebook}}
</ref> In particular, one dictionary can be loaded to process large sets of files with redundancy between files, but not necessarily within each file, e.g., [[log files]].

==Design==

Zstandard combines a dictionary-matching stage ([[LZ77]]) with a large search window and a fast [[entropy encoding|entropy coding]] stage, using both [[Finite State Entropy]] (a fast tabled version of ANS, [[asymmetric numeral systems#Tabled variant (tANS)|tANS]], used for entries in the Sequences section), and [[Huffman coding]] (used for entries in the Literals section).<ref>{{cite web|url=https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#entropy-encoding|title=facebook/zstd|website=GitHub}}</ref>

Because of the way that FSE carries over state between symbols, decompression involves processing symbols within the Sequences section of each block in reverse order (from last to first).

==Usage==
{{Infobox file format
| extension = .zst
| mime = application/zstd<ref>{{cite IETF|title=Zstandard Compression and the application/zstd Media Type|rfc=8478|publisher=Tools.ietf.org|accessdate=2019-06-13}}</ref>
| genre = [[Data compression]]
}}
The [[Linux kernel]] has included Zstandard since November 2017 (version 4.14) as a compression method for the [[btrfs]] and [[squashfs]] filesystems.<ref>{{cite web
|url=https://lwn.net/Articles/733846/
|title=The rest of the 4.14 merge window [LWN.net]
|website=lwn.net}}
</ref><ref>
{{cite web
|url=https://kernelnewbies.org/Linux_4.14
|title=Linux_4.14 - Linux Kernel Newbies
|publisher=Kernelnewbies.org
|date=
|accessdate=2018-08-16
}}
</ref><ref>
{{cite web
|url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-4.14-Zstd-Pull
|title=Zstd Compression For Btrfs & Squashfs Set For Linux 4.14, Already Used Within Facebook - Phoronix
|website=www.phoronix.com
}}</ref> This version of Linux has been used e.g. in Android since Pie.<ref>
{{cite web
|url=https://android.googlesource.com/kernel/common/+/refs/heads/android-4.14-p-release/fs/btrfs/zstd.c
|title=Zstd in Android P release.
}}</ref>

As a proof-of-concept, in 2017 Allan Jude successfully integrated Zstandard into the FreeBSD kernel as a compression method for the [[OpenZFS]] file system.<ref name=openzfs /><ref>(Was Zstandard subsequently accepted into the main FreeBSD kernel source tree?{{Citation needed|date=April 2019}})</ref>

The [[AWS Redshift]] and [[RocksDB]] databases include support for field compression using Zstandard.<ref name=Redshift>
{{cite web
|url=https://docs.aws.amazon.com/redshift/latest/dg/zstd-encoding.html
|title=Zstandard Encoding - Amazon Redshift
|date=20 April 2019
}}</ref>

In 2018 the algorithm was published as RFC 8478, which also defines an associated [[media type]] "application/zstd", [[filename extension]] "zst", and [[HTTP compression|HTTP content encoding]] "zstd".<ref name="RFC8478">
{{citation
|last=Collet
|first=Yann
|last2=Kucherawy
|first2=Murray
|title=RFC 8478: Zstandard Compression and the application/zstd Media Type
|series=Internet Engineering Task Force Request for Comments
|year=2018
|location=Menlo Park, CA|publisher=IETF Trust}}
</ref>

In March 2018, [[Canonical (company)|Canonical]] announced plans <ref>Did this actually happen?{{Citation needed|date=April 2019}}</ref> to enable zstd as a [[deb (file format)|deb package]] compression method by default, starting in version 18.10 of the [[Ubuntu (operating system)|Ubuntu]] Linux distribution. Compared with the [[XZ Utils|xz]] compression previously used for deb packages, zstd at level 19 decompresses significantly faster, but at the cost of slightly larger package files.<ref>{{cite web
|title=New Ubuntu Installs Could Be Speed Up by 10% with the Zstd Compression Algorithm
|url=https://news.softpedia.com/news/new-ubuntu-installs-could-be-speed-up-by-10-with-the-zstd-compression-algorithm-520177.shtml
|website=Softpedia
|accessdate=13 August 2018
|date=Mar 12, 2018}}
</ref><ref>
{{cite web
|title=Canonical Working On Zstd-Compressed Debian Packages For Ubuntu
|url=https://www.phoronix.com/scan.php?page=news_item&px=Ubuntu-Zstd-Deb-Packages
|website=phoronix
|accessdate=13 August 2018
|language=en
|date=12 March 2018
}}</ref>

==License==
The reference implementation is licensed under the [[BSD licenses|BSD license]], published at [[GitHub]].<ref>{{cite news|url=http://www.zdnet.com/article/facebook-open-sources-zstandard-data-compression-algorithm-aims-to-replace-technology-behind-zip/|title=Facebook open sources Zstandard data compression algorithm, aims to replace technology behind Zip|date=August 31, 2016|publisher=ZDnet|accessdate=2016-09-01}}</ref> Since version 1.0, it had an additional Grant of Patent Rights.<ref>[https://github.com/facebook/zstd/blob/v1.3.0/PATENTS zstd/PATENTS "Additional Grant of Patent Rights Version 2"], Facebook</ref>

From version 1.3.1,<ref>[https://github.com/facebook/zstd/releases/tag/v1.3.1 "Zstd v1.3.1 release"], GitHub "facebook/zstd"</ref> this patent grant was dropped and the license was changed to a BSD + GPLv2 dual license.<ref>[https://github.com/facebook/zstd/pull/801 "New license"], GitHub "facebook/zstd"</ref>

==See also==
* [[Zlib]]
* [[LZFSE]] – a similar algorithm by Apple used since iOS 9 and OS X 10.11 made open source on {{date|2016-06}}
* [[LZ4 (compression algorithm)]] – a fast member of the LZ77 family

==References==
{{Reflist}}

==External links==
* {{official website}}
* {{github|facebook/zstd}}
* "[https://code.facebook.com/posts/1658392934479273/smaller-and-faster-data-compression-with-zstandard/ Smaller and faster data compression with Zstandard]", Yann Collet and Chip Turner, 31 August 2016, Facebook Announcement
* [https://www.theguardian.com/info/developer-blog/2016/dec/01/discover-new-compression-iinovations-brotli-and-zstandard The Guardian is using ZStandard instead of zlib]

{{Compression Methods}}
{{Use dmy dates|date=August 2017}}

[[Category:Lossless compression algorithms]]
[[Category:Free data compression software]]
[[Category:C libraries]]
[[Category:2016 software]]
[[Category:Software using the BSD license]]

Zstandard

2019-07-05T17:57:16Z

Retimuko: Undid revision 904888470 by P4sven (talk) no blogs please

{{primary sources|date=September 2017}}
{{Infobox software
| name = Zstandard
| author = Yann Collet
| developer = Yann Collet, Przemysław Skibiński ([https://github.com/facebook/zstd/graphs/contributors inikep])
| operating system = [[Cross-platform]]
| genre = [[Data compression]]
| programming language = [[C (programming language)|C]]
| license = Dual: [[BSD License]] + GPLv2
| title =
| logo = Zstandard logo.png
| released = {{Start date|2015|01|23|df=y}}
| discontinued =
| latest release version = 1.4.0
| latest release date = {{Start date and age|2019|4|16|df=y}}<ref>{{cite web|url=https://github.com/facebook/zstd/releases/|accessdate=17 April 2018|title=Releases - facebook/zstd|via=[[GitHub]]}}</ref>
| latest preview version =
| platform = Portable
| size =
}}

'''Zstandard''' (or '''zstd''') is a [[lossless compression|lossless]] [[data compression]] algorithm developed by Yann Collet at [[Facebook]].
''Zstd'' is the reference implementation in [[C (programming language)|C]]. Version 1 of this implementation was released as [[free software]] on {{date|2016-08-31}}.<ref>
{{cite news
|author=Sergio De Simone
|url=https://www.infoq.com/news/2016/09/facebook-zstandard-compression
|title=Facebook Open-Sources New Compression Algorithm Outperforming Zlib
|publisher=InfoQ
|accessdate=2019-04-20
|date=2016-09-02}}
</ref><ref>{{cite news
|url=https://www.theregister.co.uk/2016/08/31/facebook_open_source_database/
|date=2016-08-31
|publisher=The Register
|accessdate=2016-09-06
|title=Life imitates satire: Facebook touts zlib killer just like Silicon Valley's Pied Piper}}
</ref>

==Features==
Zstandard was designed to give a compression ratio comparable to that of the [[DEFLATE]] algorithm (developed in 1991 and used in the original [[zip (file format)|ZIP]] and [[gzip]] programs), but faster, especially for decompression. It is tunable with compression levels ranging from negative 5 (fastest)<ref>https://github.com/facebook/zstd/releases/tag/v1.3.4 Faster compression levels</ref> to 22 (slowest in compression speed, but best compression ratio).

The zstd package includes parallel (multi-threaded) implementations of both compression and decompression. Starting from version 1.3.2 (October 2017), zstd optionally implements very long range search and deduplication similar to [[rzip]] or [[lrzip]].

Compression speed can vary by a factor of 20 or more between the fastest and slowest levels, while decompression is uniformly fast, varying by less than 20% between the fastest and slowest levels.<ref name=openzfs>
{{cite web
|url=http://www.open-zfs.org/w/images/b/b3/03-OpenZFS_2017_-_ZStandard_in_ZFS.pdf
|title=ZStandard in ZFS
|date=2017
|accessdate=2019-04-20
|website=open-zfs.org
|format=PDF
}}</ref>

''Zstd'' at its maximum compression level gives a compression ratio close to [[Lempel–Ziv–Markov chain algorithm|lzma]],
[[Lempel–Ziv–Markov chain algorithm#LZHAM|lzham]], and [[Prediction by partial matching#PPMX|ppmx]], and performs better than [[LHA (file format)|lza]], or [[bzip2]]<ref>
{{cite web
|url=http://mattmahoney.net/dc/silesia.html
|title=Silesia Open Source Compression Benchmark
|author=Matt Mahoney
|accessdate=2019-05-10}}</ref><ref>
{{cite web
|url=http://mattmahoney.net/dc/text.html
|title=Large Text Compression Benchmark, .2157 zstd
|author=Matt Mahoney
|date=2016-08-29
|accessdate=2016-09-01}}
</ref>. Zstandard reaches the current [[Pareto efficiency|Pareto frontier]], as it decompresses faster than any other currently-available algorithm with similar or better compression ratio.<ref name="web-compression">
{{citation
|title=TurboBench: Static/Dynamic web content compression benchmark
|url=https://sites.google.com/site/powturbo/home/web-compression
|publisher=PowTurbo}}
</ref><ref name="silesia-benchmark">
{{citation
|author=Matt Mahoney
|title=Silesia Open Source Compression Benchmark
|url=http://mattmahoney.net/dc/silesia.html}}
</ref>

Dictionaries can have a large impact on the compression ratio of small files, so Zstandard can use a user-provided compression dictionary. It also offers a training mode, able to generate a dictionary from a set of samples.<ref>
{{cite web
|url=https://indico.fnal.gov/event/15154/contribution/5/material/slides/0.pdf
|title=Facebook developers report massive speedups and compression ratio improvements when using dictionaries}}
</ref><ref>
{{cite web
|url=https://code.facebook.com/posts/1658392934479273/smaller-and-faster-data-compression-with-zstandard/
|title=Smaller and faster data compression with Zstandard
|date=31 August 2016
|publisher=Facebook}}
</ref>. In particular, one dictionary can be loaded to process large sets of files with redundancy between files, but not necessarily within each file, e.g., [[log files]].

==Design==

Zstandard combines a dictionary-matching stage ([[LZ77]]) with a large search window and a fast [[entropy encoding|entropy coding]] stage, using both [[Finite State Entropy]] (a fast tabled version of ANS, [[asymmetric numeral systems#Tabled variant (tANS)|tANS]], used for entries in the Sequences section), and [[Huffman coding]] (used for entries in the Literals section).<ref>{{cite web|url=https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#entropy-encoding|title=facebook/zstd|website=GitHub}}</ref>

Because of the way that FSE carries over state between symbols, decompression involves processing symbols within the Sequences section of each block in reverse order (from last to first).

==Usage==
{{Infobox file format
| extension = .zst
| mime = application/zstd<ref>{{cite IETF|title=Zstandard Compression and the application/zstd Media Type|rfc=8478|publisher=Tools.ietf.org|accessdate=2019-06-13}}</ref>
| genre = [[Data compression]]
}}
The [[Linux kernel]] has included Zstandard since November 2017 (version 4.14) as a compression method for the [[btrfs]] and [[squashfs]] filesystems.<ref>{{cite web
|url=https://lwn.net/Articles/733846/
|title=The rest of the 4.14 merge window [LWN.net]
|website=lwn.net}}
</ref><ref>
{{cite web
|url=https://kernelnewbies.org/Linux_4.14
|title=Linux_4.14 - Linux Kernel Newbies
|publisher=Kernelnewbies.org
|date=
|accessdate=2018-08-16
}}
</ref><ref>
{{cite web
|url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-4.14-Zstd-Pull
|title=Zstd Compression For Btrfs & Squashfs Set For Linux 4.14, Already Used Within Facebook - Phoronix
|website=www.phoronix.com
}}</ref> This version of Linux has been used e.g. in Android since Pie.<ref>
{{cite web
|url=https://android.googlesource.com/kernel/common/+/refs/heads/android-4.14-p-release/fs/btrfs/zstd.c
|title=Zstd in Android P release.
}}</ref>

As a proof-of-concept, in 2017 Allan Jude successfully integrated Zstandard into the FreeBSD kernel as a compression method for the [[OpenZFS]] file system.<ref name=openzfs /> <ref>(Was Zstandard subsequently accepted into the main FreeBSD kernel source tree?{{Citation needed|date=April 2019}})</ref>

The [[AWS Redshift]] and [[RocksDB]] databases include support for field compression using Zstandard.<ref name=Redshift>
{{cite web
|url=https://docs.aws.amazon.com/redshift/latest/dg/zstd-encoding.html
|title=Zstandard Encoding - Amazon Redshift
|date=20 April 2019
}}</ref>

In 2018 the algorithm was published as RFC 8478, which also defines an associated [[media type]] "application/zstd", [[filename extension]] "zst", and [[HTTP compression|HTTP content encoding]] "zstd".<ref name="RFC8478">
{{citation
|last=Collet
|first=Yann
|last2=Kucherawy
|first2=Murray
|title=RFC 8478: Zstandard Compression and the application/zstd Media Type
|series=Internet Engineering Task Force Request for Comments
|year=2018
|location=Menlo Park, CA|publisher=IETF Trust}}
</ref>

In March 2018, [[Canonical (company)|Canonical]] announced plans <ref>Did this actually happen?{{Citation needed|date=April 2019}}</ref> to enable zstd as a [[deb (file format)|deb package]] compression method by default, starting in version 18.10 of the [[Ubuntu (operating system)|Ubuntu]] Linux distribution. Compared with the [[xz]] compression previously used for deb packages, zstd at level 19 decompresses significantly faster, but at the cost of slightly larger package files.<ref>{{cite web
|title=New Ubuntu Installs Could Be Speed Up by 10% with the Zstd Compression Algorithm
|url=https://news.softpedia.com/news/new-ubuntu-installs-could-be-speed-up-by-10-with-the-zstd-compression-algorithm-520177.shtml
|website=Softpedia
|accessdate=13 August 2018
|date=Mar 12, 2018}}
</ref><ref>
{{cite web
|title=Canonical Working On Zstd-Compressed Debian Packages For Ubuntu
|url=https://www.phoronix.com/scan.php?page=news_item&px=Ubuntu-Zstd-Deb-Packages
|website=phoronix
|accessdate=13 August 2018
|language=en
|date=12 March 2018
}}</ref>

==License==
The reference implementation is licensed under the [[BSD licenses|BSD license]], published at [[GitHub]].<ref>{{cite news|url=http://www.zdnet.com/article/facebook-open-sources-zstandard-data-compression-algorithm-aims-to-replace-technology-behind-zip/|title=Facebook open sources Zstandard data compression algorithm, aims to replace technology behind Zip|date=August 31, 2016|publisher=ZDnet|accessdate=2016-09-01}}</ref> Since version 1.0, it had an additional Grant of Patent Rights.<ref>[https://github.com/facebook/zstd/blob/v1.3.0/PATENTS zstd/PATENTS "Additional Grant of Patent Rights Version 2"], Facebook</ref>

From version 1.3.1,<ref>[https://github.com/facebook/zstd/releases/tag/v1.3.1 "Zstd v1.3.1 release"], GitHub "facebook/zstd"</ref> this patent grant was dropped and the license was changed to a BSD + GPLv2 dual license.<ref>[https://github.com/facebook/zstd/pull/801 "New license"], GitHub "facebook/zstd"</ref>

==See also==
* [[Zlib]]
* [[LZFSE]] – a similar algorithm by Apple used since iOS 9 and OS X 10.11 made open source on {{date|2016-06}}
* [[LZ4 (compression algorithm)]] – a fast member of the LZ77 family

==References==
{{Reflist}}

==External links==
* {{official website}}
* {{github|facebook/zstd}}
* "[https://code.facebook.com/posts/1658392934479273/smaller-and-faster-data-compression-with-zstandard/ Smaller and faster data compression with Zstandard]", Yann Collet and Chip Turner, 31 August 2016, Facebook Announcement
* [https://www.theguardian.com/info/developer-blog/2016/dec/01/discover-new-compression-iinovations-brotli-and-zstandard The Guardian is using ZStandard instead of zlib]

{{Compression Methods}}
{{Use dmy dates|date=August 2017}}

[[Category:Lossless compression algorithms]]
[[Category:Free data compression software]]
[[Category:C libraries]]
[[Category:2016 software]]
[[Category:Software using the BSD license]]

Zstandard

2019-06-25T01:28:21Z

Retimuko: Undid revision 903314447 by 212.90.61.189 (talk) no blogs please

Swagbucks

2019-03-20T06:02:57Z

Retimuko: Undid revision 888584653 by Nidhicrypto (talk) spam

{{advert|date=December 2018}}
{{Infobox website
| name = Swagbucks
| company_type =
| company_executives =
| foundation =
| location = {{US}}
| revenue = $54 million (2013)
| date=
| net_income =
| num_employees =
| url = http://www.swagbucks.com/
| ipv6 =
| screenshot =
| caption =
| website_type = Rewards, Loyalty Program
| language = [[English language|English]]
| registration = Required, services free
| key_people = Chuck Davis, Josef Gorowitz, Scott Dudelson, Eron Zehavi
| launch_date = February 27, 2008 (11 Years)
| alexa ={{Decrease}} 1,960 ({{as of|2018|04|03|alt=April 2018}})<ref name="alexa">{{cite web|url= http://www.alexa.com/siteinfo/swagbucks.com |title= swagbucks.com Site Info | publisher= [[Alexa Internet]] |accessdate= 2018-04-03 }}</ref>
| current_status = Active
| publisher=
}}

'''Swagbucks.com''' is a rewards and loyalty-program operator operated by Prodege LLC, and based in [[El Segundo, California]].

== History ==

Swagbucks' website is owned and operated by Prodege, a provider of digital services, including an online rewards portal (Swagbucks), content distribution platforms (Yowgo, nCrave), and an online polling technology platform (SodaHead).<ref>{{cite web|url=http://news.cnet.com/8301-10784_3-9913701-7.html?tag=bl|title=Searching for swag: Music to fans' ears|publisher=|accessdate=6 September 2016}}</ref>

In 2006, Prodege introduced its first product: private label search engines that allowed charities to raise funds by having supporters perform internet searches.<ref>{{cite web|url=http://stepbystepfundraising.com/online-fundraising-prodege/|title=Raise Funds by Searching the Internet: Prodege - Step By Step Fundraising|publisher=|accessdate=6 September 2016}}</ref><ref>{{cite web|url=http://socaltech.com/interview_with_scott_dudelson_swagbucks/s-0036667.html|title=Interview with Scott Dudelson, Swagbucks - socaltech.com|publisher=|accessdate=6 September 2016}}</ref> In early 2007, Prodege developed a second search [[Loyalty program|loyalty product]] that allowed celebrities, brands and sports teams to engage fans through their own branded rewards program offering "swag" merchandise. Musicians including [[Kanye West]]<ref>{{cite web|url=http://www.billboard.com/articles/news/1046622/billboard-bits-dr-john-kanye-west|title=Billboard Bits: Dr. John, Kanye West|publisher=|accessdate=6 September 2016}}</ref> and [[Kiss (band)|Kiss]], and sports properties like [[WWE]] and the [[Indianapolis Colts]] were among the users of the platform. In February 2008, Prodege launched its current business, Swagbucks.com – under Co-Founders Josef Gorowitz and Scott Dudelson – and introduced the SB as a digital currency earned for activity throughout its network of websites.

In January 2013, Prodege Founder Josef Gorowitz appointed former [[Shopzilla]] and [[Fandango]] CEO [[Chuck Davis (businessman)|Chuck Davis]] as the company's executive chairman.<ref name=deadline>{{cite web|url=http://deadline.com/2014/05/chuck-davis-ceo-swagbucks-raises-60-million-dollars-729297/ |title=Ex-Fandango CEO Chuck Davis Joins Swagbucks; Company Raises $60M For Expansion |website=deadline.com |date=2014-05-13 |accessdate=2018-03-28}}</ref>

In May 2014, Prodege announced that Technology Crossover Ventures (TCV) had invested $60 million into Prodege,<ref>{{cite news|url=http://www.latimes.com/entertainment/envelope/cotown/la-et-ct-swagbucks-raises-60-million-former-fandango-chief-named-ceo-20140512-story.html|title=Swagbucks raises $60 million; former Fandango chief named CEO|first=Ryan|last=Faughnder|publisher=Los Angeles Times|date=May 13, 2014|accessdate=6 September 2016}}</ref> parent company of Swagbucks and other portfolio brands, and that Prodege also had appointed Executive Chairman Chuck Davis as its new CEO and Chairman,<ref>{{cite web|url=https://www.forbes.com/sites/lorikozlowski/2014/01/29/cash-for-internet/|title=Cash For Internet: How And Why One Site Pays For Clicks|first=Lori|last=Kozlowski|publisher=|accessdate=6 September 2016}}</ref> while Josef Gorowitz assumed the title of Founder and President. This was the company's first external investment. Prior to the TCV investment, Prodege had been fully bootstrapped and had grown to $53 million in profitable revenue in 2013.

In July 2014, Prodege announced its acquisition of [[SodaHead.com]], an online polling technology platform founded by Jason Feffer.<ref>{{cite web|url=http://upstart.bizjournals.com/money/loot/2014/07/31/swagbucks-acquires-sodahead-and-now-they-ll-be-key.html?page=all|title=Swagbucks acquired SodaHead and now they’ll be kings of web polling|publisher=|accessdate=6 September 2016}}</ref> SodaHead.com CEO Chris Dominguez and Founder Jason Feffer joined Prodege's executive leadership team in the move. SodaHead operates a consumer website and provides polling technology to media partners including ESPN, FOX News, and Good Morning America.

== Full site ==
Members of the Swagbucks program are able to earn and redeem SB in a variety of ways through the Swagbucks website and mobile apps. While a single SB is generally worth 1 US cent (¢), the value may be greater when used for certain rewards.

== Mobile site and applications ==
A mobile version of the Swagbucks site is available for use on smartphones like [[iPhone]] and [[Android (operating system)|Android]] devices. It is a stripped-down version of the regular site that contains fewer features, but is optimized for use via touchscreen.

Earning:

* Searching: Just like the regular site, users can search using the mobile site and periodically earn SB.
* Special Offers: A mobile version of the special offers on the regular Swagbucks site.
* Daily Poll: Also available on the regular site, a new poll is posted each day, and answering it rewards 1 SB.

Redeeming:

* A selection of popular gift cards for major retailers are available on mobile, including Amazon, Walmart, Target and others.

===Swagbucks mobile apps for iOS and Android===
Swagbucks has released mobile apps on both [[Google Play]] and the [[App Store (iOS)|App Store]] that allow the user to check their SB balances, perform mobile searches, answer the daily poll, complete special offers, and redeem SB for a selection of popular gift cards for major retailers, including Amazon, Walmart, Target and others.

===Swagbucks TV===
Swagbucks has also released separate mobile apps on both Google Play and the Apple App Store for the Swagbucks TV feature.

===Swagbucks Answer===

Swagbucks has introduced a new mobile app on Google Play and the Apple App Store that is meant specifically for survey taking.
<ref>https://play.google.com/store/apps/details?id=com.prodege.answer</ref>

==Awards and accolades==

{{awards table}}
|-
| 2014
| ''Josef Gorowitz, Founder of Prodege / Swagbucks''
| [[Ernst & Young]] Entrepreneur of the Year: Los Angeles, Advertising Category
| {{won}}
|-
| 2014
| ''Brad Kates, [[Chief financial officer|CFO]] of Prodege / Swagbucks''
| [[Los Angeles Business Journal]]: CFO of the Year
| {{won}}
|-
| 2014
| ''Shane O'Neill, CTO of Prodege / Swagbucks''
| Los Angeles Business Journal: CIO of the Year
| {{nominated}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #28 for 2014''
| Los Angeles Business Journal, Best Places to Work Awards
| {{won}}
|-
| 2011–2014
|''Prodege / Swagbucks, #41 for 2014''
| Los Angeles Business Journal Fast Growing Private Companies
| {{won}}
|-
| 2013–2014
| ''Prodege / Swagbucks, #96 for 2014''
| [[Deloitte Fast 500]] Fastest Growing Private Companies
| {{won}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #1,245 for 2014
| Inc. 5000
| {{won}}
|}

== References ==
{{Reflist|2}}

== External links ==
* [http://www.swagbucks.com Homepage]


[[Category:Reward websites]]
[[Category:Internet properties established in 2008]]
[[Category:2008 establishments in California]]
[[Category:Companies based in Los Angeles County, California]]

Swagbucks

2019-02-16T05:36:15Z

Retimuko: Undid revision 883568059 by Kittencorn87 (talk) editorial opinion

{{advert|date=December 2018}}
{{Infobox website
| name = Swagbucks
| company_type =
| company_executives =
| foundation =
| location = {{US}}
| revenue = $54 million (2013)
| date=
| net_income =
| num_employees =
| url = http://www.swagbucks.com/
| ipv6 =
| screenshot =
| caption =
| website_type = Rewards, Loyalty Program
| language = [[English language|English]]
| registration = Required, services free
| key_people = Chuck Davis, Josef Gorowitz, Scott Dudelson, Eron Zehavi
| launch_date = February 27, 2008 (10 Years)
| alexa ={{Decrease}} 1,960 ({{as of|2018|04|03|alt=April 2018}})<ref name="alexa">{{cite web|url= http://www.alexa.com/siteinfo/swagbucks.com |title= swagbucks.com Site Info | publisher= [[Alexa Internet]] |accessdate= 2018-04-03 }}</ref>
| current_status = Active
| publisher=
}}

'''Swagbucks.com''' is a rewards and loyalty-program operator operated by Prodege LLC, and based in [[El Segundo, California]].

== History ==

Swagbucks' website is owned and operated by Prodege, a provider of digital services, including an online rewards portal (Swagbucks), content distribution platforms (Yowgo, nCrave), and an online polling technology platform (SodaHead).<ref>{{cite web|url=http://news.cnet.com/8301-10784_3-9913701-7.html?tag=bl|title=Searching for swag: Music to fans' ears|publisher=|accessdate=6 September 2016}}</ref>

In 2006, Prodege introduced its first product: private label search engines that allowed charities to raise funds by having supporters perform internet searches.<ref>{{cite web|url=http://stepbystepfundraising.com/online-fundraising-prodege/|title=Raise Funds by Searching the Internet: Prodege - Step By Step Fundraising|publisher=|accessdate=6 September 2016}}</ref><ref>{{cite web|url=http://socaltech.com/interview_with_scott_dudelson_swagbucks/s-0036667.html|title=Interview with Scott Dudelson, Swagbucks - socaltech.com|publisher=|accessdate=6 September 2016}}</ref> In early 2007, Prodege developed a second search [[Loyalty program|loyalty product]] that allowed celebrities, brands and sports teams to engage fans through their own branded rewards program offering "swag" merchandise. Musicians including [[Kanye West]]<ref>{{cite web|url=http://www.billboard.com/articles/news/1046622/billboard-bits-dr-john-kanye-west|title=Billboard Bits: Dr. John, Kanye West|publisher=|accessdate=6 September 2016}}</ref> and [[Kiss (band)|Kiss]], and sports properties like [[WWE]] and the [[Indianapolis Colts]] were among the users of the platform. In February 2008, Prodege launched its current business, Swagbucks.com – under Co-Founders Josef Gorowitz and Scott Dudelson – and introduced the SB as a digital currency earned for activity throughout its network of websites.

In January 2013, Prodege Founder Josef Gorowitz appointed former [[Shopzilla]] and [[Fandango]] CEO [[Chuck Davis (businessman)|Chuck Davis]] as the company's executive chairman.<ref name=deadline>{{cite web|url=http://deadline.com/2014/05/chuck-davis-ceo-swagbucks-raises-60-million-dollars-729297/ |title=Ex-Fandango CEO Chuck Davis Joins Swagbucks; Company Raises $60M For Expansion |website=deadline.com |date=2014-05-13 |accessdate=2018-03-28}}</ref>

In May 2014, Prodege announced that Technology Crossover Ventures (TCV) had invested $60 million into Prodege,<ref>{{cite news|url=http://www.latimes.com/entertainment/envelope/cotown/la-et-ct-swagbucks-raises-60-million-former-fandango-chief-named-ceo-20140512-story.html|title=Swagbucks raises $60 million; former Fandango chief named CEO|first=Ryan|last=Faughnder|publisher=Los Angeles Times|date=May 13, 2014|accessdate=6 September 2016}}</ref> parent company of Swagbucks and other portfolio brands, and that Prodege also had appointed Executive Chairman Chuck Davis as its new CEO and Chairman,<ref>{{cite web|url=https://www.forbes.com/sites/lorikozlowski/2014/01/29/cash-for-internet/|title=Cash For Internet: How And Why One Site Pays For Clicks|first=Lori|last=Kozlowski|publisher=|accessdate=6 September 2016}}</ref> while Josef Gorowitz assumed the title of Founder and President. This was the company's first external investment. Prior to the TCV investment, Prodege had been fully bootstrapped and had grown to $53 million in profitable revenue in 2013.

In July 2014, Prodege announced its acquisition of [[SodaHead.com]], an online polling technology platform founded by Jason Feffer.<ref>{{cite web|url=http://upstart.bizjournals.com/money/loot/2014/07/31/swagbucks-acquires-sodahead-and-now-they-ll-be-key.html?page=all|title=Swagbucks acquired SodaHead and now they’ll be kings of web polling|publisher=|accessdate=6 September 2016}}</ref> SodaHead.com CEO Chris Dominguez and Founder Jason Feffer joined Prodege's executive leadership team in the move. SodaHead operates a consumer website and provides polling technology to media partners including ESPN, FOX News, and Good Morning America.

== Full site ==
Members of the Swagbucks program are able to earn and redeem SB in a variety of ways through the Swagbucks website and mobile apps. While a single SB is generally worth 1 US cent (¢), the value may be greater when used for certain rewards.

== Mobile site and applications ==
A mobile version of the Swagbucks site is available for use on smartphones like [[iPhone]] and [[Android (operating system)|Android]] devices. It is a stripped-down version of the regular site that contains fewer features, but is optimized for use via touchscreen.

Earning:

* Searching: Just like the regular site, users can search using the mobile site and periodically earn SB.
* Special Offers: A mobile version of the special offers on the regular Swagbucks site.
* Daily Poll: Also available on the regular site, a new poll is posted each day, and answering it rewards 1 SB.

Redeeming:

* A selection of popular gift cards for major retailers are available on mobile, including Amazon, Walmart, Target and others.

===Swagbucks mobile apps for iOS and Android===
Swagbucks has released mobile apps on both [[Google Play]] and the [[App Store (iOS)|App Store]] that allow the user to check their SB balances, perform mobile searches, answer the daily poll, complete special offers, and redeem SB for a selection of popular gift cards for major retailers, including Amazon, Walmart, Target and others.

===Swagbucks TV===
Swagbucks has also released separate mobile apps on both Google Play and the Apple App Store for the Swagbucks TV feature.

===Swagbucks Answer===

Swagbucks has introduced a new mobile app on Google Play and the Apple App Store that is meant specifically for survey taking.
<ref>https://play.google.com/store/apps/details?id=com.prodege.answer</ref>

==Awards and accolades==

{{awards table}}
|-
| 2014
| ''Josef Gorowitz, Founder of Prodege / Swagbucks''
| [[Ernst & Young]] Entrepreneur of the Year: Los Angeles, Advertising Category
| {{won}}
|-
| 2014
| ''Brad Kates, [[Chief financial officer|CFO]] of Prodege / Swagbucks''
| [[Los Angeles Business Journal]]: CFO of the Year
| {{won}}
|-
| 2014
| ''Shane O'Neill, CTO of Prodege / Swagbucks''
| Los Angeles Business Journal: CIO of the Year
| {{nominated}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #28 for 2014''
| Los Angeles Business Journal, Best Places to Work Awards
| {{won}}
|-
| 2011–2014
|''Prodege / Swagbucks, #41 for 2014''
| Los Angeles Business Journal Fast Growing Private Companies
| {{won}}
|-
| 2013–2014
| ''Prodege / Swagbucks, #96 for 2014''
| [[Deloitte Fast 500]] Fastest Growing Private Companies
| {{won}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #1,245 for 2014
| Inc. 5000
| {{won}}
|}

== References ==
{{Reflist|2}}

== External links ==
* [http://www.swagbucks.com Homepage]


[[Category:Reward websites]]
[[Category:Internet properties established in 2008]]
[[Category:2008 establishments in California]]
[[Category:Companies based in Los Angeles County, California]]

Zstandard

2019-01-02T23:20:16Z

Retimuko: Undid revision 876539282 by 2A02:530:24:3B6:D4FA:443C:A984:DE5F (talk) irrelevant, looks like spam

{{primary sources|date=September 2017}}
{{Infobox software
| name = Zstandard
| author = Yann Collet
| developer = Yann Collet, Przemysław Skibiński ([https://github.com/facebook/zstd/graphs/contributors inikep])
| operating system = [[Cross-platform]]
| genre = [[Data compression]]
| programming language = [[C (programming language)|C]]
| license = Dual: [[BSD License]] + GPLv2
| title =
| logo = Zstandard logo.png
| released = {{Start date|2015|01|23|df=y}}
| discontinued =
| latest release version = 1.3.8
| latest release date = {{Start date and age|2018|12|27|df=y}}<ref>{{cite web|url=https://github.com/facebook/zstd/releases/|accessdate=27 December 2018|title=Releases - facebook/zstd|via=[[GitHub]]}}</ref>
| latest preview version =
| platform = Portable
| size =
| status = Active
}}
'''Zstandard''' (or '''Zstd''') is a [[lossless compression|lossless]] [[data compression]] algorithm developed by Yann Collet at [[Facebook]]. The name also refers to the reference implementation in [[C (programming language)|C]].
Version 1 of the implementation was released as [[free software]] on {{date|2016-08-31}}.<ref>Sergio De Simone, [https://www.infoq.com/news/2016/09/facebook-zstandard-compression Facebook Open-Sources New Compression Algorithm Outperforming Zlib] / InfoQ, 2 September 2016</ref><ref>{{cite news|url=https://www.theregister.co.uk/2016/08/31/facebook_open_source_database/|date=2016-08-31|publisher=The Register|accessdate=2016-09-06|title=Life imitates satire: Facebook touts zlib killer just like Silicon Valley's Pied Piper}}</ref>

==Features==
Zstandard has been designed to give compression comparable to that of the [[DEFLATE]] algorithm (developed in 1991, used in original [[zip (file format)|ZIP]], [[gzip]] and others) with higher compression and especially decompression speeds. Zstandard combines the use of a dictionary-type algorithm ([[LZ77]]) with a large search window and fast implementations of [[entropy encoding|entropy coding]] stage, using either very fast [[Finite State Entropy]] ([[asymmetric numeral systems#Tabled variant (tANS)|tANS]]) or Huffman coding.<ref>{{cite web|url=https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#entropy-encoding|title=facebook/zstd|website=GitHub}}</ref> A feature of the Zstandard implementations is backward direction of reading on entropy decompression.

Zstandard also implements several compression levels for additional flexibility, ranging from 1 (fastest) to 22 (slowest in compression speed, but best compression ratio). There are also  parallel (multi-threaded) implementations of both compression and decompression. Starting from 1.3.2 version (October 2017), Zstandard optionally implements very long range search and deduplication similar to [[rzip]] or [[lrzip]].

According to the LTCB compression benchmark compressing a single 1 GB text file, ''zstd'' at maximum levels shows compression ratio close to boz, yxz, tornado archivers, and performs better than lza, brotli, or [[bzip2]]. With any compression level it has fast decompression.<ref>{{cite web|url=http://mattmahoney.net/dc/text.html|title=Large Text Compression Benchmark, .2157 zstd|author=Matt Mahoney|date=2016-08-29|accessdate=2016-09-01}}</ref> Zstandard reaches the [[Pareto efficiency|Pareto frontier]], which means it decompresses faster than any other currently-available algorithm with similar or better compression ratio.<ref name="web-compression">{{citation|title=TurboBench: Static/Dynamic web content compression benchmark|url=https://sites.google.com/site/powturbo/home/web-compression|publisher=PowTurbo}}</ref><ref name="silesia-benchmark">{{citation|author=Matt Mahoney|title=Silesia Open Source Compression Benchmark|url=http://mattmahoney.net/dc/silesia.html}}</ref>

Zstandard can use any user-defined pre-populated compression dictionary. It also offers a training mode, able to generate a dictionary from any set of samples. Dictionaries can have a large impact on the compression ratio of small files.<ref>https://indico.fnal.gov/event/15154/contribution/5/material/slides/0.pdf "Facebook developers report massive speedups and compression ratio improvements when using dictionaries"</ref><ref>{{cite web|url=https://code.facebook.com/posts/1658392934479273/smaller-and-faster-data-compression-with-zstandard/|title=Smaller and faster data compression with Zstandard|date=31 August 2016|publisher=Facebook}}</ref>. In particular, one dictionary can be loaded to process large amounts of data with redundancy between, but not necessarily within, a set of files, e.g., [[log files]].

==Usage==
Zstandard method is supported in the [[Linux kernel]] since version 4.14 (released November 2017) for usage as compression method for file systems like [[btrfs]] and [[squashfs]].<ref>{{cite web|url=https://lwn.net/Articles/733846/|title=The rest of the 4.14 merge window [LWN.net]|website=lwn.net}}</ref><ref>{{cite web|url=https://kernelnewbies.org/Linux_4.14 |title=Linux_4.14 - Linux Kernel Newbies |publisher=Kernelnewbies.org |date= |accessdate=2018-08-16}}</ref><ref>{{cite web|url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-4.14-Zstd-Pull|title=Zstd Compression For Btrfs & Squashfs Set For Linux 4.14, Already Used Within Facebook - Phoronix|website=www.phoronix.com}}</ref> It was also tested for FreeBSD with integration into [[OpenZFS]] file system.<ref>{{cite web|url=http://www.open-zfs.org/w/images/b/b3/03-OpenZFS_2017_-_ZStandard_in_ZFS.pdf |title=Info |date=2017 |website=open-zfs.org|format=PDF}} </ref>

The algorithm is also deployed in datacenters, such as AWS Redshift, and in databases, such as RocksDB.


In 2018 the algorithm was published as RFC 8478, which also defines an associated [[media type]] "application/zstd", [[filename extension]] "zst", and [[HTTP compression|HTTP content encoding]] "zstd".<ref name="RFC8478">{{citation|last=Collet|first=Yann|last2=Kucherawy|first2=Murray|title=RFC 8478: Zstandard Compression and the application/zstd Media Type|series=Internet Engineering Task Force Request for Comments|year=2018|location=Menlo Park, CA|publisher=IETF Trust}}.</ref>

[[Canonical (company)|Canonical]] has plans to change default [[deb (file format)|deb package]] compression to zstd in version 18.10 of the [[Ubuntu (operating system)|Ubuntu]] Linux distribution to speed up installation by around 10 percent. Zstd compression at level 19 has larger packages than the previously used [[xz]] compression, but faster decompression speed.<ref>{{cite web |title=New Ubuntu Installs Could Be Speed Up by 10% with the Zstd Compression Algorithm |url=https://news.softpedia.com/news/new-ubuntu-installs-could-be-speed-up-by-10-with-the-zstd-compression-algorithm-520177.shtml |website=Softpedia |accessdate=13 August 2018 |date=Mar 12, 2018}}</ref><ref>{{cite web |title=Canonical Working On Zstd-Compressed Debian Packages For Ubuntu |url=https://www.phoronix.com/scan.php?page=news_item&px=Ubuntu-Zstd-Deb-Packages |website=phoronix |accessdate=13 August 2018 |language=en |date=12 March 2018}}</ref>

==License==
The reference implementation is licensed under the [[BSD licenses|BSD license]], published at [[GitHub]].<ref>{{cite news|url=http://www.zdnet.com/article/facebook-open-sources-zstandard-data-compression-algorithm-aims-to-replace-technology-behind-zip/|title=Facebook open sources Zstandard data compression algorithm, aims to replace technology behind Zip|date=August 31, 2016|publisher=ZDnet|accessdate=2016-09-01}}</ref> Since version 1.0, it had an additional Grant of Patent Rights.<ref>[https://github.com/facebook/zstd/blob/dev/PATENTS zstd/PATENTS "Additional Grant of Patent Rights Version 2"], Facebook</ref>

From version 1.3.1,<ref>[https://github.com/facebook/zstd/releases/tag/v1.3.1 "Zstd v1.3.1 release"], GitHub "facebook/zstd"</ref> this patent grant was dropped and the license was changed to a BSD + GPLv2 dual license.<ref>[https://github.com/facebook/zstd/pull/801 "New license"], GitHub "facebook/zstd"</ref>

==See also==
* [[Zlib]]
* [[LZFSE]] – a similar algorithm by Apple used since iOS 9 and OS X 10.11 made open source on {{date|2016-06}}
* [[LZ4 (compression algorithm)]] – a fast member of the LZ77 family

==References==
{{Reflist}}

==External links==
* {{official website}}
* {{github|facebook/zstd}}
* "[https://code.facebook.com/posts/1658392934479273/smaller-and-faster-data-compression-with-zstandard/ Smaller and faster data compression with Zstandard]", Yann Collet and Chip Turner, 31 August 2016, Facebook Announcement
* [https://www.theguardian.com/info/developer-blog/2016/dec/01/discover-new-compression-iinovations-brotli-and-zstandard The Guardian is using ZStandard instead of zlib]

{{Compression Methods}}
{{Use dmy dates|date=August 2017}}

[[Category:Lossless compression algorithms]]
[[Category:Free data compression software]]
[[Category:C libraries]]
[[Category:2016 software]]
[[Category:Software using the BSD license]]

Zcash

2018-11-06T17:09:54Z

Retimuko: Undid revision 867580333 by 103.52.12.132 (talk) rvv

{{about-distinguish|the cryptocurrency Zcash|Zerocoin|zcache}}
{{Use dmy dates|date=February 2016}}
{{Infobox cryptocurrency
| ticker_symbol = ZEC
| image_1 = Zcash logo.svg
| image_title_1 = Zcash logo
| initial_release_date = {{Start date and age|df=yes|2016|10|28}}
| iso_code = ZEC{{efn|Unofficial.|group=infobox}}
| footnotes = {{notelist|group=infobox}}
| status = Active
| hash_function = [[SNARK|zk-SNARKs]]
| website = https://z.cash
| block_explorer = https://explorer.zcha.in/
| code_repository = https://github.com/zcash/zcash
}}
'''Zcash''' is a [[cryptocurrency]] aimed at using [[cryptography]] to provide enhanced privacy for its users compared to other cryptocurrencies such as [[Bitcoin]]. The Zerocoin protocol was improved and transformed into the Zerocash system, which was then developed into the Zcash cryptocurrency in 2016.<ref name=Southurst/> Development of [[cryptographic protocol|protocol]] improvements and the [[reference implementation]] is led by the Zerocoin Electric Coin Company, colloquially referred to as Zcash Company.<ref name=NYT/><ref name=companyfiling>{{Cite web|url=https://opencorporates.com/companies/us_de/5638987|title=THE ZEROCOIN ELECTRIC COIN COMPANY LLC|accessdate=2017-12-19|publisher=Delaware Department of State: Division of Corporations}}</ref> The founder and CEO of Zcash Company is [[Zooko Wilcox-O'Hearn]]. Its founding team includes cryptographer [[Matthew D. Green]] from [[Johns Hopkins University]]. [[Roger Ver]] was one of Zcash Company's initial investors.<ref name=Southurst/>

==Details==
Zcash is an open source, decentralized payment system software. The Zcash Co emphasizes non-exclusion and the right to privacy as "essential for core human values like dignity, intimacy and ethics."
Zcash payments are published on a public [[blockchain]], but users are able to use an optional privacy feature to conceal the sender, recipient, and amount being transacted.<ref name=Southurst>{{Cite web|url=https://news.bitcoin.com/snowden-zcash-bitcoin-risks/|title=Snowden: Anonymous 'Zcash' Could Solve Bitcoin Surveillance Risks|accessdate=2016-10-08|author=Jon Southurst|date=2016-06-07|publisher=Bitcoin News}}</ref> Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref name=NYT>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times}}</ref>
In the first four years, 20% of the coins created in that period are allocated to a "founders' reward" shared between investors, developers, and the Zcash Foundation. The Zcash Foundation is a 501(c)3 nonprofit organization (EIN 82-0707962) created on February 14, 2017.<ref>{{cite web|url=https://web.archive.org/web/20170616150438/https://petertodd.org/2016/cypherpunk-desert-bus-zcash-trusted-setup-ceremony#founders-reward|author=[[Peter Todd]]|date=2016-11-14|title=Cypherpunk Desert Bus: My Role In The 2016 Zcash Trusted Setup Ceremony}}</ref>

Transactions can be "transparent" and similar to bitcoin transactions in which case they are controlled by a t-addr, or can be a type of zero-knowledge proof called [[Non-interactive zero-knowledge proof|zk-SNARK]]s; the transactions are then said to be "shielded" and are controlled by a z-addr. Zcash coins are either in a transparent pool or a shielded pool; as of December 2017 only around 4% of Zcash coins were in the shielded pool and at that time most wallet programs did not support z-addrs and no web-based wallets supported them.<ref name=quesnelle>{{cite arXiv|last=Quesnelle|first=Jeffrey|eprint=1712.01210|title=On the linkability of Zcash transactions|class=cs.CR|date=2017}}</ref>

Zcash affords private transactors the option of "selective disclosure", allowing a user to prove payment for auditing purposes. One such reason is to allow private transactors the choice to comply with anti-money laundering or tax regulations. "Transactions are auditable but disclosure is under the participant's control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=October 31, 2016|language=en}}</ref> Wilcox has hosted virtual meetings with law enforcement agencies around the U.S. to explain these fundamentals and has gone on the record of saying that "they did not develop the currency to facilitate illegal activity".<ref name=NYT/>

== See also ==
* [[Legality of bitcoin by country]]
* [[SNARK|zk-SNARKs]]
* [[Bitcoin Private]]

== References ==
{{Reflist|30em}}

==External links==
* [https://z.cash/ Official website]

{{Cryptocurrencies|state=expanded}}
{{Authority control}}

{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]
[[Category:Computer-related introductions in 2016]]

Zcash

2018-10-30T15:47:45Z

Retimuko: Undid revision 866453367 by Albertojohnson (talk) bad source

Zcash

2018-09-27T03:32:38Z

Retimuko: Undid revision 861391836 by 96.60.255.141 (talk) why?

{{about-distinguish|the cryptocurrency Zcash|Zerocoin|zcache}}
{{Use dmy dates|date=February 2016}}
{{Infobox currency
| image_1 = Zcash logo.svg
| image_title_1 = Zcash logo
| date_of_introduction = {{Start date and age|df=yes|2016|10|28}}
| using_countries = Worldwide
| inflation_title = [[Monetary inflation|Supply growth]]
| inflation_rate =
| inflation_source_date =
| iso_code = ZEC{{efn|Unofficial.|group=infobox}}
| footnotes = {{notelist|group=infobox}}
}}
'''Zcash''' is a [[cryptocurrency]] aimed at using [[cryptography]] to provide enhanced privacy for its users compared to other cryptocurrencies such as [[Bitcoin]]. The Zerocoin protocol was improved and transformed into the Zerocash system, which was then developed into the Zcash cryptocurrency in 2016.<ref name=Southurst/> Development of [[cryptographic protocol|protocol]] improvements and the [[reference implementation]] is led by the Zerocoin Electric Coin Company, colloquially referred to as Zcash Company.<ref name=NYT/><ref name=companyfiling>{{Cite web|url=https://opencorporates.com/companies/us_de/5638987|title=THE ZEROCOIN ELECTRIC COIN COMPANY LLC|accessdate=2017-12-19|publisher=Delaware Department of State: Division of Corporations}}</ref> The founder and CEO of Zcash Company is [[Zooko Wilcox-O'Hearn]]. Its founding team includes cryptographer [[Matthew D. Green]] from [[Johns Hopkins University]]. [[Roger Ver]] was one of Zcash Company's initial investors.<ref name=Southurst/>

==Details==
Zcash is an open source, decentralized payment system software. The Zcash Co emphasizes non-exclusion and the right to privacy as "essential for core human values like dignity, intimacy and ethics."
Zcash payments are published on a public [[blockchain]], but users are able to use an optional privacy feature to conceal the sender, recipient, and amount being transacted.<ref name=Southurst>{{Cite web|url=https://news.bitcoin.com/snowden-zcash-bitcoin-risks/|title=Snowden: Anonymous 'Zcash' Could Solve Bitcoin Surveillance Risks|accessdate=2016-10-08|author=Jon Southurst|date=2016-06-07|publisher=Bitcoin News}}</ref> Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref name=NYT>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times}}</ref>
In the first four years, 20% of the coins created in that period are allocated to a "founders' reward" shared between investors, developers, and the Zcash Foundation. The Zcash Foundation is a 501(c)3 nonprofit organization (EIN 82-0707962) created on February 14, 2017.<ref>{{cite web|url=https://web.archive.org/web/20170616150438/https://petertodd.org/2016/cypherpunk-desert-bus-zcash-trusted-setup-ceremony#founders-reward|author=[[Peter Todd]]|date=2016-11-14|title=Cypherpunk Desert Bus: My Role In The 2016 Zcash Trusted Setup Ceremony}}</ref>

Transactions can be "transparent" and similar to bitcoin transactions in which case they are controlled by a t-addr, or can be a type of zero-knowledge proof called [[Non-interactive zero-knowledge proof|zk-SNARK]]s; the transactions are then said to be "shielded" and are controlled by a z-addr. Zcash coins are either in a transparent pool or a shielded pool; as of December 2017 only around 4% of Zcash coins were in the shielded pool and at that time most wallet programs did not support z-addrs and no web-based wallets supported them.<ref name=quesnelle>{{cite arXiv|last=Quesnelle|first=Jeffrey|eprint=1712.01210|title=On the linkability of Zcash transactions|class=cs.CR|date=2017}}</ref>

Zcash affords private transactors the option of "selective disclosure", allowing a user to prove payment for auditing purposes. One such reason is to allow private transactors the choice to comply with anti-money laundering or tax regulations. "Transactions are auditable but disclosure is under the participant's control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=October 31, 2016|language=en}}</ref> Wilcox has hosted virtual meetings with law enforcement agencies around the U.S. to explain these fundamentals and has gone on the record of saying that "they did not develop the currency to facilitate illegal activity".<ref name=NYT/>

== See also ==
* [[Legality of bitcoin by country]]
* [[SNARK|zk-SNARKs]]
* [[Bitcoin Private]]

== References ==
{{Reflist|30em}}

==External links==
* [https://z.cash/ Official website]

{{Cryptocurrencies|state=expanded}}
{{Authority control}}

{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]
[[Category:Computer-related introductions in 2016]]

Zcash

2018-09-14T01:05:02Z

Retimuko: /* Details */ do we need these US-specific technicalities?

{{about-distinguish|the cryptocurrency Zcash|Zerocoin|zcache}}
{{Use dmy dates|date=February 2016}}
{{Infobox currency
| image_1 = Zcash logo.svg
| image_title_1 = Zcash logo
| date_of_introduction = {{Start date and age|df=yes|2016|10|28}}
| using_countries = Worldwide
| inflation_title = [[Monetary inflation|Supply growth]]
| inflation_rate =
| inflation_source_date =
| iso_code = ZEC{{efn|Unofficial.|group=infobox}}
| footnotes = {{notelist|group=infobox}}
}}
'''Zcash''' is a [[cryptocurrency]] aimed at using [[cryptography]] to provide enhanced privacy for its users compared to other cryptocurrencies such as [[Bitcoin]]. The Zerocoin protocol was improved and transformed into the Zerocash system, which was then developed into the Zcash cryptocurrency in 2016.<ref name=Southurst/> Development of [[cryptographic protocol|protocol]] improvements and the [[reference implementation]] is led by the Zerocoin Electric Coin Company, colloquially referred to as Zcash Company.<ref name=NYT/><ref name=companyfiling>{{Cite web|url=https://opencorporates.com/companies/us_de/5638987|title=THE ZEROCOIN ELECTRIC COIN COMPANY LLC|accessdate=2017-12-19|publisher=Delaware Department of State: Division of Corporations}}</ref> The founder and CEO of Zcash Company is [[Zooko Wilcox-O'Hearn]]. Its founding team includes cryptographer [[Matthew D. Green]] from [[Johns Hopkins University]]. [[Roger Ver]] was one of Zcash Company's initial investors.<ref name=Southurst/>

==Details==
Zcash payments are published on a public [[blockchain]], but users are able to use an optional privacy feature to conceal the sender, recipient, and amount being transacted.<ref name=Southurst>{{Cite web|url=https://news.bitcoin.com/snowden-zcash-bitcoin-risks/|title=Snowden: Anonymous 'Zcash' Could Solve Bitcoin Surveillance Risks|accessdate=2016-10-08|author=Jon Southurst|date=2016-06-07|publisher=Bitcoin News}}</ref> Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref name=NYT>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times}}</ref>
In the first four years, 20% of the coins created in that period are allocated to a "founders' reward" shared between investors, developers, and the Zcash Foundation. The Zcash Foundation is a 501(c)3 nonprofit organization (EIN 82-0707962) created on February 14, 2017.<ref>{{cite web|url=https://web.archive.org/web/20170616150438/https://petertodd.org/2016/cypherpunk-desert-bus-zcash-trusted-setup-ceremony#founders-reward|author=[[Peter Todd]]|date=2016-11-14|title=Cypherpunk Desert Bus: My Role In The 2016 Zcash Trusted Setup Ceremony}}</ref>

Transactions can be "transparent" and similar to bitcoin transactions in which case they are controlled by a t-addr, or can be a type of zero-knowledge proof called [[Non-interactive zero-knowledge proof|zk-SNARK]]s; the transactions are then said to be "shielded" and are controlled by a z-addr. Zcash coins are either in a transparent pool or a shielded pool; as of December 2017 only around 4% of Zcash coins were in the shielded pool and at that time most wallet programs did not support z-addrs and no web-based wallets supported them.<ref name=quesnelle>{{cite arXiv|last=Quesnelle|first=Jeffrey|eprint=1712.01210|title=On the linkability of Zcash transactions|class=cs.CR|date=2017}}</ref>

Zcash affords private transactors the option of "selective disclosure", allowing a user to prove payment for auditing purposes. One such reason is to allow private transactors the choice to comply with anti-money laundering or tax regulations. "Transactions are auditable but disclosure is under the participant's control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=October 31, 2016|language=en}}</ref> Wilcox has hosted virtual meetings with law enforcement agencies around the U.S. to explain these fundamentals and has gone on the record of saying that "they did not develop the currency to facilitate illegal activity".<ref name=NYT/>

== See also ==
* [[Legality of bitcoin by country]]
* [[SNARK|zk-SNARKs]]
* [[Bitcoin Private]]

== References ==
{{Reflist|30em}}

==External links==
* [https://z.cash/ Official website]

{{Cryptocurrencies|state=expanded}}
{{Authority control}}

{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]
[[Category:Computer-related introductions in 2016]]

Swagbucks

2018-08-07T17:52:23Z

Retimuko: rvv

{{Infobox website
| name = Swagbucks
| company_type =
| company_executives =
| foundation =
| location = {{US}}
| revenue = $54 million (2013)
| date=
| net_income =
| num_employees =
| url = http://www.swagbucks.com/
| ipv6 =
| screenshot =
| caption =
| website_type = Rewards, Loyalty Program
| language = [[English language|English]]
| registration = Required, services free
| key_people = Chuck Davis, Josef Gorowitz, Scott Dudelson, Eron Zehavi
| launch_date = February 27, 2008 (10 Years)
| alexa ={{Decrease}} 1,960 ({{as of|2018|04|03|alt=April 2018}})<ref name="alexa">{{cite web|url= http://www.alexa.com/siteinfo/swagbucks.com |title= swagbucks.com Site Info | publisher= [[Alexa Internet]] |accessdate= 2018-04-03 }}</ref>
| current_status = Active
| publisher=
}}

'''Swagbucks.com''' is a rewards and loyalty-program operator operated by Prodege LLC, and based in [[El Segundo, California]].

== History ==

Swagbucks' website is owned and operated by Prodege, a provider of digital services, including an online rewards portal (Swagbucks), content distribution platforms (Yowgo, nCrave), and an online polling technology platform (SodaHead).<ref>{{cite web|url=http://news.cnet.com/8301-10784_3-9913701-7.html?tag=bl|title=Searching for swag: Music to fans' ears|publisher=|accessdate=6 September 2016}}</ref>

In 2006, Prodege introduced its first product: private label search engines that allowed charities to raise funds by having supporters perform internet searches.<ref>{{cite web|url=http://stepbystepfundraising.com/online-fundraising-prodege/|title=Raise Funds by Searching the Internet: Prodege - Step By Step Fundraising|publisher=|accessdate=6 September 2016}}</ref><ref>{{cite web|url=http://socaltech.com/interview_with_scott_dudelson_swagbucks/s-0036667.html|title=Interview with Scott Dudelson, Swagbucks - socaltech.com|publisher=|accessdate=6 September 2016}}</ref> In early 2007, Prodege developed a second search [[Loyalty program|loyalty product]] that allowed celebrities, brands and sports teams to engage fans through their own branded rewards program offering "swag" merchandise. Musicians including [[Kanye West]]<ref>{{cite web|url=http://www.billboard.com/articles/news/1046622/billboard-bits-dr-john-kanye-west|title=Billboard Bits: Dr. John, Kanye West|publisher=|accessdate=6 September 2016}}</ref> and [[Kiss (band)|Kiss]], and sports properties like [[WWE]] and the [[Indianapolis Colts]] were among the users of the platform. In February 2008, Prodege launched its current business, Swagbucks.com – under Co-Founders Josef Gorowitz and Scott Dudelson – and introduced the SB as a digital currency earned for activity throughout its network of websites.

In January 2013, Prodege Founder Josef Gorowitz appointed former [[Shopzilla]] and [[Fandango]] CEO [[Chuck Davis (businessman)|Chuck Davis]] as the company's executive chairman.<ref name=deadline>{{cite web|url=http://deadline.com/2014/05/chuck-davis-ceo-swagbucks-raises-60-million-dollars-729297/ |title=Ex-Fandango CEO Chuck Davis Joins Swagbucks; Company Raises $60M For Expansion |website=deadline.com |date=2014-05-13 |accessdate=2018-03-28}}</ref>

In May 2014, Prodege announced that Technology Crossover Ventures (TCV) had invested $60 million into Prodege,<ref>{{cite news|url=http://www.latimes.com/entertainment/envelope/cotown/la-et-ct-swagbucks-raises-60-million-former-fandango-chief-named-ceo-20140512-story.html|title=Swagbucks raises $60 million; former Fandango chief named CEO|first=Ryan|last=Faughnder|publisher=Los Angeles Times|date=May 13, 2014|accessdate=6 September 2016}}</ref> parent company of Swagbucks and other portfolio brands, and that Prodege also had appointed Executive Chairman Chuck Davis as its new CEO and Chairman,<ref>{{cite web|url=https://www.forbes.com/sites/lorikozlowski/2014/01/29/cash-for-internet/|title=Cash For Internet: How And Why One Site Pays For Clicks|first=Lori|last=Kozlowski|publisher=|accessdate=6 September 2016}}</ref> while Josef Gorowitz assumed the title of Founder and President. This was the company’s first external investment. Prior to the TCV investment, Prodege had been fully bootstrapped and had grown to $53 million in profitable revenue in 2013.

In July 2014, Prodege announced its acquisition of [[SodaHead.com]], an online polling technology platform founded by Jason Feffer.<ref>{{cite web|url=http://upstart.bizjournals.com/money/loot/2014/07/31/swagbucks-acquires-sodahead-and-now-they-ll-be-key.html?page=all|title=Swagbucks acquired SodaHead and now they’ll be kings of web polling|publisher=|accessdate=6 September 2016}}</ref> SodaHead.com CEO Chris Dominguez and Founder Jason Feffer joined Prodege’s executive leadership team in the move. SodaHead operates a consumer website and provides polling technology to media partners including ESPN, FOX News, and Good Morning America.

== Full site ==
Members of the Swagbucks program are able to earn and redeem SB in a variety of ways through the Swagbucks website and mobile apps. While a single SB is generally worth 1 US cent (¢), the value may be greater when used for certain rewards.

== Mobile site and applications ==
A mobile version of the Swagbucks site is available for use on smartphones like [[iPhone]] and [[Android (operating system)|Android]] devices. It is a stripped-down version of the regular site that contains fewer features, but is optimized for use via touchscreen.

Earning:

* Searching: Just like the regular site, users can search using the mobile site and periodically earn SB.
* Special Offers: A mobile version of the special offers on the regular Swagbucks site.
* Daily Poll: Also available on the regular site, a new poll is posted each day, and answering it rewards 1 SB.

Redeeming:

* A selection of popular gift cards for major retailers are available on mobile, including Amazon, Walmart, Target and others.

===Swagbucks mobile apps for iOS and Android===
Swagbucks has released mobile apps on both [[Google Play]] and the [[App Store (iOS)|App Store]] that allow the user to check their SB balances, perform mobile searches, answer the daily poll, complete special offers, and redeem SB for a selection of popular gift cards for major retailers, including Amazon, Walmart, Target and others.

===Swagbucks TV===
Swagbucks has also released separate mobile apps on both Google Play and the Apple App Store for the Swagbucks TV feature.

===Swagbucks Answer===

Swagbucks has introduced a new mobile app on Google Play and the Apple App Store that is meant specifically for survey taking.
<ref>https://play.google.com/store/apps/details?id=com.prodege.answer</ref>

==Awards and accolades==

{{awards table}}
|-
| 2014
| ''Josef Gorowitz, Founder of Prodege / Swagbucks''
| [[Ernst & Young]] Entrepreneur of the Year: Los Angeles, Advertising Category
| {{won}}
|-
| 2014
| ''Brad Kates, [[Chief financial officer|CFO]] of Prodege / Swagbucks''
| [[Los Angeles Business Journal]]: CFO of the Year
| {{won}}
|-
| 2014
| ''Shane O'Neill, CTO of Prodege / Swagbucks''
| Los Angeles Business Journal: CIO of the Year
| {{nominated}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #28 for 2014''
| Los Angeles Business Journal, Best Places to Work Awards
| {{won}}
|-
| 2011–2014
|''Prodege / Swagbucks, #41 for 2014''
| Los Angeles Business Journal Fast Growing Private Companies
| {{won}}
|-
| 2013–2014
| ''Prodege / Swagbucks, #96 for 2014''
| [[Deloitte Fast 500]] Fastest Growing Private Companies
| {{won}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #1,245 for 2014
| Inc. 5000
| {{won}}
|}

== References ==
{{Reflist|2}}

== External links ==
* [http://www.swagbucks.com Homepage]


[[Category:Articles created via the Article Wizard]]
[[Category:Reward websites]]
[[Category:Internet properties established in 2008]]
[[Category:2008 establishments in California]]
[[Category:Companies based in Los Angeles County, California]]

Zcash

2018-07-12T19:22:42Z

Retimuko: Undid revision 849977627 by 96.82.104.98 (talk) link spam

{{about-distinguish|the cryptocurrency Zcash|Zerocoin|zcache}}
{{Use dmy dates|date=February 2016}}
{{Infobox currency
| image_1 = Zcash logo.svg
| image_title_1 = Zcash logo
| date_of_introduction = {{Start date and age|df=yes|2016|10|28}}
| using_countries = Worldwide
| inflation_title = [[Monetary inflation|Supply growth]]
| inflation_rate =
| inflation_source_date =
| iso_code = ZEC{{efn|Unofficial.|group=infobox}}
| footnotes = {{notelist|group=infobox}}
}}
'''Zcash''' is a [[cryptocurrency]] aimed at using [[cryptography]] to provide enhanced privacy for its users compared to other cryptocurrencies such as [[Bitcoin]]. The Zerocoin protocol was improved and transformed into the Zerocash system, which was then developed into the Zcash cryptocurrency in 2016.<ref name=Southurst/> Development of [[cryptographic protocol|protocol]] improvements and the [[reference implementation]] is led by the Zerocoin Electric Coin Company, colloquially referred to as Zcash Company.<ref name=NYT/><ref name=companyfiling>{{Cite web|url=https://opencorporates.com/companies/us_de/5638987|title=THE ZEROCOIN ELECTRIC COIN COMPANY LLC|accessdate=2017-12-19|publisher=Delaware Department of State: Division of Corporations}}</ref> The founder and CEO of Zcash Company is [[Zooko Wilcox-O'Hearn]]. Its founding team includes cryptographer [[Matthew D. Green]] from [[Johns Hopkins University]]. [[Roger Ver]] was one of Zcash Company's initial investors.<ref name=Southurst/>

==Details==
Zcash payments are published on a public [[blockchain]], but users are able to use an optional privacy feature to conceal the sender, recipient, and amount being transacted.<ref name=Southurst>{{Cite web|url=https://news.bitcoin.com/snowden-zcash-bitcoin-risks/|title=Snowden: Anonymous 'Zcash' Could Solve Bitcoin Surveillance Risks|accessdate=2016-10-08|author=Jon Southurst|date=2016-06-07|publisher=Bitcoin News}}</ref> Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref name=NYT>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times}}</ref>
In the first four years, 20% of the coins created in that period are allocated to a "founders' reward" shared between investors, developers, and a non-profit foundation.<ref>{{cite web|url=https://web.archive.org/web/20170616150438/https://petertodd.org/2016/cypherpunk-desert-bus-zcash-trusted-setup-ceremony#founders-reward|author=[[Peter Todd]]|date=2016-11-14|title=Cypherpunk Desert Bus: My Role In The 2016 Zcash Trusted Setup Ceremony}}</ref>

Transactions can be "transparent" and similar to bitcoin transactions in which case they are controlled by a t-addr, or can be a type of zero-knowledge proof called [[Non-interactive zero-knowledge proof|zk-SNARK]]s; the transactions are then said to be "shielded" and are controlled by a z-addr. Zcash coins are either in a transparent pool or a shielded pool; as of December 2017 only around 4% of Zcash coins were in the shielded pool and at that time most wallet programs did not support z-addrs and no web-based wallets supported them.<ref name=quesnelle>{{cite arXiv|last=Quesnelle|first=Jeffrey|eprint=1712.01210|title=On the linkability of Zcash transactions|class=cs.CR|date=2017}}</ref>

Zcash affords private transactors the option of "selective disclosure", allowing a user to prove payment for auditing purposes. One such reason is to allow private transactors the choice to comply with anti-money laundering or tax regulations. "Transactions are auditable but disclosure is under the participant's control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=October 31, 2016|language=en}}</ref> Wilcox has hosted virtual meetings with law enforcement agencies around the U.S. to explain these fundamentals and has gone on the record of saying that "they did not develop the currency to facilitate illegal activity".<ref name=NYT/>

==Network upgrade==
The first network upgrade of Zcash will be done through a hard fork at the block number 347500<ref>{{Cite web|url=https://z.cash/upgrade/overwinter.html|title=Zcash - Overwinter Network Upgrade|website=z.cash|language=en|access-date=2018-05-05}}</ref> which is expected to be on 25 June 2018. A new feature will be introduced that allows users to set transaction expiration times.<ref>{{Cite web|url=https://ecoin4dummies.com/2018/03/27/overwinter-zcash-network-upgrade/|title=Overwinter – A Zcash network upgrade|last=|first=|date=|website=eCoin4Dummies.com|archive-url=|archive-date=|dead-url=|access-date=}}</ref> Five Zcash Improvement Proposals namely, 143, 200, 201, 203 will be implemented<ref>{{Cite web|url=https://github.com/zcash/zips/pulls?q=is:pr+label:Overwinter|title=zcash/zips|website=GitHub|language=en|access-date=2018-05-05}}</ref>. This upgrade also improved the signature verification that helps improve the transaction speed.

== See also ==
* [[Legality of bitcoin by country]]
* [[SNARK|zk-SNARKs]]
* [[Bitcoin Private]]

== References ==
{{Reflist|30em}}

==External links==
* [https://z.cash/ Official website]

{{Cryptocurrencies}}
{{Authority control}}

{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]
[[Category:Computer-related introductions in 2016]]

Swagbucks

2018-04-04T03:24:44Z

Retimuko: removed unsupported template parameter

{{Infobox dot-com company
| name = Swagbucks
| company_type =
| company_executives =
| foundation =
| location = {{US}}
| revenue = $54 million (2013)
| date=
| net_income =
| num_employees =
| url = http://www.swagbucks.com/
| ipv6 =
| screenshot =
| caption =
| website_type = Rewards, Loyalty Program
| language = [[English language|English]]
| registration = Required, services free
| key_people = Chuck Davis, Josef Gorowitz, Scott Dudelson, Eron Zehavi
| launch_date = February 27, 2008 (9 Years)
| alexa ={{Decrease}} 1,960 ({{as of|2018|04|03|alt=April 2018}})<ref name="alexa">{{cite web|url= http://www.alexa.com/siteinfo/swagbucks.com |title= swagbucks.com Site Info | publisher= [[Alexa Internet]] |accessdate= 2018-04-03 }}</ref>
| current_status = Active
| publisher=
}}

'''Swagbucks.com''' is a rewards and loyalty-program operator operated by Prodege LLC, and based in [[El Segundo, California]].

== History ==

Swagbucks' website is owned and operated by Prodege, a provider of digital services, including an online rewards portal (Swagbucks), content distribution platforms (Yowgo, nCrave), and an online polling technology platform (SodaHead).<ref>{{cite web|url=http://news.cnet.com/8301-10784_3-9913701-7.html?tag=bl|title=Searching for swag: Music to fans' ears|publisher=|accessdate=6 September 2016}}</ref>

In 2006, Prodege introduced its first product: private label search engines that allowed charities to raise funds by having supporters perform internet searches.<ref>{{cite web|url=http://stepbystepfundraising.com/online-fundraising-prodege/|title=Raise Funds by Searching the Internet: Prodege - Step By Step Fundraising|publisher=|accessdate=6 September 2016}}</ref><ref>{{cite web|url=http://socaltech.com/interview_with_scott_dudelson_swagbucks/s-0036667.html|title=Interview with Scott Dudelson, Swagbucks - socaltech.com|publisher=|accessdate=6 September 2016}}</ref> In early 2007, Prodege developed a second search [[Loyalty program|loyalty product]] that allowed celebrities, brands and sports teams to engage fans through their own branded rewards program offering "swag" merchandise. Musicians including [[Kanye West]]<ref>{{cite web|url=http://www.billboard.com/articles/news/1046622/billboard-bits-dr-john-kanye-west|title=Billboard Bits: Dr. John, Kanye West|publisher=|accessdate=6 September 2016}}</ref> and [[Kiss (band)|Kiss]], and sports properties like [[WWE]] and the [[Indianapolis Colts]] were among the users of the platform. In February 2008, Prodege launched its current business, Swagbucks.com – under Co-Founders Josef Gorowitz and Scott Dudelson – and introduced the SB as a digital currency earned for activity throughout its network of websites.

In January 2013, Prodege Founder Josef Gorowitz appointed former [[Shopzilla]] and [[Fandango]] CEO [[Chuck Davis (businessman)|Chuck Davis]] as the company's executive chairman.<ref name=deadline>{{cite web|url=http://deadline.com/2014/05/chuck-davis-ceo-swagbucks-raises-60-million-dollars-729297/ |title=Ex-Fandango CEO Chuck Davis Joins Swagbucks; Company Raises $60M For Expansion |website=deadline.com |date=2014-05-13 |accessdate=2018-03-28}}</ref>

In May 2014, Prodege announced that Technology Crossover Ventures (TCV) had invested $60 million into Prodege,<ref>{{cite news|url=http://www.latimes.com/entertainment/envelope/cotown/la-et-ct-swagbucks-raises-60-million-former-fandango-chief-named-ceo-20140512-story.html|title=Swagbucks raises $60 million; former Fandango chief named CEO|first=Ryan|last=Faughnder|publisher=Los Angeles Times|date=May 13, 2014|accessdate=6 September 2016}}</ref> parent company of Swagbucks and other portfolio brands, and that Prodege also had appointed Executive Chairman Chuck Davis as its new CEO and Chairman,<ref>{{cite web|url=https://www.forbes.com/sites/lorikozlowski/2014/01/29/cash-for-internet/|title=Cash For Internet: How And Why One Site Pays For Clicks|first=Lori|last=Kozlowski|publisher=|accessdate=6 September 2016}}</ref> while Josef Gorowitz assumed the title of Founder and President. This was the company’s first external investment. Prior to the TCV investment, Prodege had been fully bootstrapped and had grown to $53 million in profitable revenue in 2013.

In July 2014, Prodege announced its acquisition of [[SodaHead.com]], an online polling technology platform founded by Jason Feffer.<ref>{{cite web|url=http://upstart.bizjournals.com/money/loot/2014/07/31/swagbucks-acquires-sodahead-and-now-they-ll-be-key.html?page=all|title=Swagbucks acquired SodaHead and now they’ll be kings of web polling|publisher=|accessdate=6 September 2016}}</ref> SodaHead.com CEO Chris Dominguez and Founder Jason Feffer joined Prodege’s executive leadership team in the move. SodaHead operates a consumer website and provides polling technology to media partners including ESPN, FOX News, and Good Morning America.

== Full site ==
Members of the Swagbucks program are able to earn and redeem SB in a variety of ways through the Swagbucks website and mobile apps. While a single SB is generally worth 1 US cent (¢), the value may be greater when used for certain rewards.

== Mobile site and applications ==
A mobile version of the Swagbucks site is available for use on smartphones like [[iPhone]] and [[Android (operating system)|Android]] devices. It is a stripped-down version of the regular site that contains fewer features, but is optimized for use via touchscreen.

Earning:

* Searching: Just like the regular site, users can search using the mobile site and periodically earn SB.
* Special Offers: A mobile version of the special offers on the regular Swagbucks site.
* Daily Poll: Also available on the regular site, a new poll is posted each day, and answering it rewards 1 SB.

Redeeming:

* A selection of popular gift cards for major retailers are available on mobile, including Amazon, Walmart, Target and others.

===Swagbucks mobile apps for iOS and Android===
Swagbucks has released mobile apps on both [[Google Play]] and the [[App Store (iOS)|App Store]] that allow the user to check their SB balances, perform mobile searches, answer the daily poll, complete special offers, and redeem SB for a selection of popular gift cards for major retailers, including Amazon, Walmart, Target and others.

===Swagbucks TV===
Swagbucks has also released separate mobile apps on both Google Play and the Apple App Store for the Swagbucks TV feature.

===Swagbucks Answer===

Swagbucks has introduced a new mobile app on Google Play and the Apple App Store that is meant specifically for survey taking.
<ref>https://play.google.com/store/apps/details?id=com.prodege.answer</ref>

==Awards and accolades==

{{awards table}}
|-
| 2014
| ''Josef Gorowitz, Founder of Prodege / Swagbucks''
| [[Ernst & Young]] Entrepreneur of the Year: Los Angeles, Advertising Category
| {{won}}
|-
| 2014
| ''Brad Kates, [[Chief financial officer|CFO]] of Prodege / Swagbucks''
| [[Los Angeles Business Journal]]: CFO of the Year
| {{won}}
|-
| 2014
| ''Shane O'Neill, CTO of Prodege / Swagbucks''
| Los Angeles Business Journal: CIO of the Year
| {{nominated}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #28 for 2014''
| Los Angeles Business Journal, Best Places to Work Awards
| {{won}}
|-
| 2011–2014
|''Prodege / Swagbucks, #41 for 2014''
| Los Angeles Business Journal Fast Growing Private Companies
| {{won}}
|-
| 2013–2014
| ''Prodege / Swagbucks, #96 for 2014''
| [[Deloitte Fast 500]] Fastest Growing Private Companies
| {{won}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #1,245 for 2014
| Inc. 5000
| {{won}}
|}

== References ==
{{Reflist|2}}

== External links ==
* [http://www.swagbucks.com Homepage]


[[Category:Articles created via the Article Wizard]]
[[Category:Reward websites]]
[[Category:Internet properties established in 2008]]
[[Category:2008 establishments in California]]
[[Category:Companies based in Los Angeles County, California]]

Swagbucks

2018-04-04T03:22:16Z

Retimuko: fixed ref

{{Infobox dot-com company
| name = Swagbucks
| company_type =
| company_executives =
| foundation =
| location = {{US}}
| revenue = $54 million (2013)
| date=
| net_income =
| num_employees =
| url = http://www.swagbucks.com/
| ipv6 =
| screenshot =
| caption =
| website_type = Rewards, Loyalty Program
| language = [[English language|English]]
| registration = Required, services free
| Rewards_Distributed = $98,000,000
| key_people = Chuck Davis, Josef Gorowitz, Scott Dudelson, Eron Zehavi
| launch_date = February 27, 2008 (9 Years)
| alexa ={{Decrease}} 1,960 ({{as of|2018|04|03|alt=April 2018}})<ref name="alexa">{{cite web|url= http://www.alexa.com/siteinfo/swagbucks.com |title= swagbucks.com Site Info | publisher= [[Alexa Internet]] |accessdate= 2018-04-03 }}</ref>
| current_status = Active
| publisher=
}}

'''Swagbucks.com''' is a rewards and loyalty-program operator operated by Prodege LLC, and based in [[El Segundo, California]].

== History ==

Swagbucks' website is owned and operated by Prodege, a provider of digital services, including an online rewards portal (Swagbucks), content distribution platforms (Yowgo, nCrave), and an online polling technology platform (SodaHead).<ref>{{cite web|url=http://news.cnet.com/8301-10784_3-9913701-7.html?tag=bl|title=Searching for swag: Music to fans' ears|publisher=|accessdate=6 September 2016}}</ref>

In 2006, Prodege introduced its first product: private label search engines that allowed charities to raise funds by having supporters perform internet searches.<ref>{{cite web|url=http://stepbystepfundraising.com/online-fundraising-prodege/|title=Raise Funds by Searching the Internet: Prodege - Step By Step Fundraising|publisher=|accessdate=6 September 2016}}</ref><ref>{{cite web|url=http://socaltech.com/interview_with_scott_dudelson_swagbucks/s-0036667.html|title=Interview with Scott Dudelson, Swagbucks - socaltech.com|publisher=|accessdate=6 September 2016}}</ref> In early 2007, Prodege developed a second search [[Loyalty program|loyalty product]] that allowed celebrities, brands and sports teams to engage fans through their own branded rewards program offering "swag" merchandise. Musicians including [[Kanye West]]<ref>{{cite web|url=http://www.billboard.com/articles/news/1046622/billboard-bits-dr-john-kanye-west|title=Billboard Bits: Dr. John, Kanye West|publisher=|accessdate=6 September 2016}}</ref> and [[Kiss (band)|Kiss]], and sports properties like [[WWE]] and the [[Indianapolis Colts]] were among the users of the platform. In February 2008, Prodege launched its current business, Swagbucks.com – under Co-Founders Josef Gorowitz and Scott Dudelson – and introduced the SB as a digital currency earned for activity throughout its network of websites.

In January 2013, Prodege Founder Josef Gorowitz appointed former [[Shopzilla]] and [[Fandango]] CEO [[Chuck Davis (businessman)|Chuck Davis]] as the company's executive chairman.<ref name=deadline>{{cite web|url=http://deadline.com/2014/05/chuck-davis-ceo-swagbucks-raises-60-million-dollars-729297/ |title=Ex-Fandango CEO Chuck Davis Joins Swagbucks; Company Raises $60M For Expansion |website=deadline.com |date=2014-05-13 |accessdate=2018-03-28}}</ref>

In May 2014, Prodege announced that Technology Crossover Ventures (TCV) had invested $60 million into Prodege,<ref>{{cite news|url=http://www.latimes.com/entertainment/envelope/cotown/la-et-ct-swagbucks-raises-60-million-former-fandango-chief-named-ceo-20140512-story.html|title=Swagbucks raises $60 million; former Fandango chief named CEO|first=Ryan|last=Faughnder|publisher=Los Angeles Times|date=May 13, 2014|accessdate=6 September 2016}}</ref> parent company of Swagbucks and other portfolio brands, and that Prodege also had appointed Executive Chairman Chuck Davis as its new CEO and Chairman,<ref>{{cite web|url=https://www.forbes.com/sites/lorikozlowski/2014/01/29/cash-for-internet/|title=Cash For Internet: How And Why One Site Pays For Clicks|first=Lori|last=Kozlowski|publisher=|accessdate=6 September 2016}}</ref> while Josef Gorowitz assumed the title of Founder and President. This was the company’s first external investment. Prior to the TCV investment, Prodege had been fully bootstrapped and had grown to $53 million in profitable revenue in 2013.

In July 2014, Prodege announced its acquisition of [[SodaHead.com]], an online polling technology platform founded by Jason Feffer.<ref>{{cite web|url=http://upstart.bizjournals.com/money/loot/2014/07/31/swagbucks-acquires-sodahead-and-now-they-ll-be-key.html?page=all|title=Swagbucks acquired SodaHead and now they’ll be kings of web polling|publisher=|accessdate=6 September 2016}}</ref> SodaHead.com CEO Chris Dominguez and Founder Jason Feffer joined Prodege’s executive leadership team in the move. SodaHead operates a consumer website and provides polling technology to media partners including ESPN, FOX News, and Good Morning America.

== Full site ==
Members of the Swagbucks program are able to earn and redeem SB in a variety of ways through the Swagbucks website and mobile apps. While a single SB is generally worth 1 US cent (¢), the value may be greater when used for certain rewards.

== Mobile site and applications ==
A mobile version of the Swagbucks site is available for use on smartphones like [[iPhone]] and [[Android (operating system)|Android]] devices. It is a stripped-down version of the regular site that contains fewer features, but is optimized for use via touchscreen.

Earning:

* Searching: Just like the regular site, users can search using the mobile site and periodically earn SB.
* Special Offers: A mobile version of the special offers on the regular Swagbucks site.
* Daily Poll: Also available on the regular site, a new poll is posted each day, and answering it rewards 1 SB.

Redeeming:

* A selection of popular gift cards for major retailers are available on mobile, including Amazon, Walmart, Target and others.

===Swagbucks mobile apps for iOS and Android===
Swagbucks has released mobile apps on both [[Google Play]] and the [[App Store (iOS)|App Store]] that allow the user to check their SB balances, perform mobile searches, answer the daily poll, complete special offers, and redeem SB for a selection of popular gift cards for major retailers, including Amazon, Walmart, Target and others.

===Swagbucks TV===
Swagbucks has also released separate mobile apps on both Google Play and the Apple App Store for the Swagbucks TV feature.

===Swagbucks Answer===

Swagbucks has introduced a new mobile app on Google Play and the Apple App Store that is meant specifically for survey taking.
<ref>https://play.google.com/store/apps/details?id=com.prodege.answer</ref>

==Awards and accolades==

{{awards table}}
|-
| 2014
| ''Josef Gorowitz, Founder of Prodege / Swagbucks''
| [[Ernst & Young]] Entrepreneur of the Year: Los Angeles, Advertising Category
| {{won}}
|-
| 2014
| ''Brad Kates, [[Chief financial officer|CFO]] of Prodege / Swagbucks''
| [[Los Angeles Business Journal]]: CFO of the Year
| {{won}}
|-
| 2014
| ''Shane O'Neill, CTO of Prodege / Swagbucks''
| Los Angeles Business Journal: CIO of the Year
| {{nominated}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #28 for 2014''
| Los Angeles Business Journal, Best Places to Work Awards
| {{won}}
|-
| 2011–2014
|''Prodege / Swagbucks, #41 for 2014''
| Los Angeles Business Journal Fast Growing Private Companies
| {{won}}
|-
| 2013–2014
| ''Prodege / Swagbucks, #96 for 2014''
| [[Deloitte Fast 500]] Fastest Growing Private Companies
| {{won}}
|-
| 2011–2014
| ''Prodege / Swagbucks, #1,245 for 2014
| Inc. 5000
| {{won}}
|}

== References ==
{{Reflist|2}}

== External links ==
* [http://www.swagbucks.com Homepage]


[[Category:Articles created via the Article Wizard]]
[[Category:Reward websites]]
[[Category:Internet properties established in 2008]]
[[Category:2008 establishments in California]]
[[Category:Companies based in Los Angeles County, California]]

Zcash

2017-10-19T17:51:48Z

Retimuko: Undid revision 805926051 by 101.51.127.112 (talk) spam

{{about-distinguish|the cryptocurrency Zcash|Zerocoin|zcache}}
{{Use dmy dates|date=February 2016}}
{{Infobox currency
| image_1 = File:Zcash-logo-black.png
| image_title_1 = Zcash logo
| date_of_introduction = {{Start date and age|df=yes|2016|10|28}}
| using_countries = Worldwide
| inflation_title = [[Monetary inflation|Supply growth]]
| inflation_rate =
| inflation_source_date =
| iso_code =
| footnotes = {{notelist|group=infobox}}
}}

'''Zcash''' is a [[cryptocurrency]] that grew out of the [[Zerocoin]] project, aimed at improving anonymity for [[Bitcoin]] users. The Zerocoin protocol was initially improved and transformed into Zerocash, which thus yielded the Zcash cryptocurrency in 2016.<ref name=Southurst/> The founder and CEO of Zcash is [[Zooko Wilcox-O'Hearn]]. Its founding team includes cryptographer [[Matthew D. Green]] from [[Johns Hopkins University]]. [[Roger Ver]] was one of Zcash's initial investors.<ref name=Southurst/>

Zcash payments are published on a public blockchain, but users are able to use an optional privacy feature to conceal the sender, recipient, and amount being transacted.<ref name=Southurst>{{Cite web|url=https://news.bitcoin.com/snowden-zcash-bitcoin-risks/|title=Snowden: Anonymous 'Zcash' Could Solve Bitcoin Surveillance Risks|accessdate=2016-10-08|author=Jon Southurst|date=2016-06-07|publisher=Bitcoin News}}</ref> Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref name=NYT>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times}}</ref>

Zcash affords private transactors the option of "selective disclosure", allowing a user to prove payment for auditing purposes. One such reason is to allow private transactors the choice to comply with anti-money laundering or tax regulations. "Transactions are auditable but disclosure is under the participant's control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=October 31, 2016|language=en}}</ref> Wilcox has hosted virtual meetings with law enforcement agencies around the U.S. to explain these fundamentals and has gone on the record of saying that "they did not develop the currency to facilitate illegal activity".<ref name=NYT/>

On April 4, 2017, Zcash entered the top 10 cryptocurrencies by market cap.<ref>{{cite news|last1=Bovaird|first1=Charles|title=Zcash Enters Top 10 Cryptocurrencies By Market Cap - CoinDesk|url=https://www.coindesk.com/zcash-enters-top-10-cryptocurrencies-market-cap/|work=CoinDesk|date=4 April 2017}}</ref>

== See also ==
* [[Legality of bitcoin by country]]
* [[SNARK|zk-SNARKs]]

== References ==
{{Reflist|30em}}

==External links==
* [https://z.cash/ Official website]

{{Cryptocurrencies}}
{{Authority control}}

{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]

Zcash

2017-09-28T04:41:51Z

Retimuko: Undid revision 802738754 by 178.89.21.31 (talk) not a reliable source

{{about-distinguish|the cryptocurrency Zcash|Zerocoin}}
{{Use dmy dates|date=February 2016}}
{{Infobox currency
| image_1 = File:Zcash-logo-black.png
| image_title_1 = Zcash logo
| date_of_introduction = {{Start date and age|df=yes|2016|10|28}}
| using_countries = Worldwide
| inflation_title = [[Monetary inflation|Supply growth]]
| inflation_rate =
| inflation_source_date =
| iso_code =
| footnotes = {{notelist|group=infobox}}
}}

'''Zcash''' is a [[cryptocurrency]] that grew out of the [[Zerocoin]] project, aimed at improving anonymity for [[Bitcoin]] users. The Zerocoin protocol was initially improved and transformed into Zerocash, which thus yielded the Zcash cryptocurrency in 2016.<ref name=Southurst/> The founder and CEO of Zcash is [[Zooko Wilcox-O'Hearn]]. Its founding team includes cryptographer [[Matthew D. Green]] from [[Johns Hopkins University]]. [[Roger Ver]] was one of Zcash's initial investors.<ref name=Southurst/>

Zcash payments are published on a public blockchain, but users are able to use an optional privacy feature to conceal the sender, recipient, and amount being transacted.<ref name=Southurst>{{Cite web|url=https://news.bitcoin.com/snowden-zcash-bitcoin-risks/|title=Snowden: Anonymous 'Zcash' Could Solve Bitcoin Surveillance Risks|accessdate=2016-10-08|author=Jon Southurst|date=2016-06-07|publisher=Bitcoin News}}</ref> Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref name=NYT>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times}}</ref>

Zcash affords private transactors the option of "selective disclosure", allowing a user to prove payment for auditing purposes. One such reason is to allow private transactors the choice to comply with anti-money laundering or tax regulations. "Transactions are auditable but disclosure is under the participant's control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=October 31, 2016|language=en}}</ref> Wilcox has hosted virtual meetings with law enforcement agencies around the U.S to explain these fundamentals and has gone on the record of saying that "they did not develop the currency to facilitate illegal activity".<ref name=NYT/>

On April 4, 2017, Zcash entered the top 10 cryptocurrencies by market cap.<ref>{{cite news|last1=Bovaird|first1=Charles|title=Zcash Enters Top 10 Cryptocurrencies By Market Cap - CoinDesk|url=https://www.coindesk.com/zcash-enters-top-10-cryptocurrencies-market-cap/|work=CoinDesk|date=4 April 2017}}</ref>

== See also ==
* [[Legality of bitcoin by country]]
* [[SNARK|zk-SNARKs]]

== References ==
{{Reflist|30em}}

==External links==
* [https://z.cash/ Official website]

{{Cryptocurrencies}}
{{Authority control}}

{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]

Zcash

2017-09-05T18:01:53Z

Retimuko: fixed date format

{{about-distinguish|the cryptocurrency Zcash|Zerocoin}}
{{refimprove|date=October 2016}}
{{Use dmy dates|date=February 2016}}
{{Infobox currency
| image_1 = File:Zcash-logo-black.png
| image_title_1 = Zcash logo
| date_of_introduction = {{Start date and age|df=yes|2016|10|28}}
| using_countries = Worldwide
| inflation_title = [[Monetary inflation|Supply growth]]
| inflation_rate =
| inflation_source_date =
| iso_code = ZEC{{efn|Unofficial.|group=infobox}}
| footnotes = {{notelist|group=infobox}}
}}


'''Zcash''' is a [[cryptocurrency]] that offers privacy and selective transparency of transactions. Zcash payments are published on a public blockchain, but the sender, recipient, and amount of a transaction may remain private.<ref>{{Cite web|url=https://news.bitcoin.com/snowden-zcash-bitcoin-risks/|title=Snowden: Anonymous 'Zcash' Could Solve Bitcoin Surveillance Risks|accessdate=2016-10-08|author=Jon Southurst|date=2016-06-07|publisher=Bitcoin.com}}</ref><ref>{{Cite web|url=https://z.cash/about.html|title=Zcash - About|accessdate=2016-10-08|quote=Zcash is a decentralized and open-source cryptocurrency that offers both private and transparent transaction types. Zcash payments are published on a public blockchain, but the sender, recipient, and amount of a transaction remain private.}}</ref> The Zcash trade symbol, ZEC, is not an official [[ISO 4217#Cryptocurrencies|ISO 4217]]. Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times|issn=0362-4331|access-date=2017-01-26}}</ref>
{{TOC limit|3}}

== Technology ==

===Privacy===

==== Comparison ====
On traditional blockchains such as [[Bitcoin]] and [[Ethereum]], every entry into the blockchain reveals both the amount of the transaction and the parties involved in the transaction. Bitcoin's [[CoinJoin]] obfuscates the amounts and recipients by allowing users to pool transactions together. It does not hide the total amount value of the pooled transactions, only how the total amount is split between future transactions. It also requires active participation between clients.

[[Bitshares|BitShares]] 1.0 featured the ability to hide the total transaction amount, but not the receiver and recipient of the transaction. However, total transaction amounts can leak by checking the values of previous and future transactions.<ref>{{Cite web|url=https://bytemaster.github.io/article/2014/12/23/How-to-Maintain-Privacy-with-BitShares/ |title=How to Maintain Privacy with BitShares |last=Larimer |first=Daniel |date=2014-12-03 |website=Bytemaster's Blog |archive-url=https://archive.fo/20170512081620/https://bytemaster.github.io/article/2014/12/23/How-to-Maintain-Privacy-with-BitShares/%23 |archive-date=12 May 2017 |dead-url=yes |access-date= |df= }}</ref> [[Monero (cryptocurrency)|Monero]] goes a step further in creating a large number of dummy inputs and outputs for each transaction, creating a much larger set of addresses connected to a given transaction. This too can leak information as clients must create dummy transactions that mimic real transactions. Between April 2014 and January 2017, 62% of all Monero transactions were linkable due to client software creating dummy inputs to transactions from wallets without any balance. Other patterns leaked information about 90% of transactions.<ref>{{cite arxiv|last=Miller|first=Andrew|date=April 2017|title=An Empirical Analysis of Linkability in the Monero Blockchain|eprint=1704.04299}}</ref>

==== Zcash ====
Zcash uses novel cryptographic zero-knowledge proofs ([[SNARK|zk-SNARKs]]) to protect both amount and recipient on special, "shielded" transactions. This increases the set of potential inputs and outputs for a given shielded transaction, to potentially every shielded address on the Zcash blockchain that an adversary cannot exclude via other sources of information.<ref>{{Cite web|url=https://z.cash/blog/anatomy-of-zcash.html|title=Anatomy of A Zcash Transaction|last=|first=|date=Nov 23, 2016|website=|access-date=}}</ref> Although the probability of a shielded input corresponding to any previous shielded output is not uniform (for example, older addresses are less likely to be in use), no information about this is leaked by the transaction itself, other than what can be inferred from timing and metadata (number of shielded transfers, etc). In principle, this is as large as the anonymity set for any public blockchain can become, as a transaction must be recorded.

Zcash also allows for transparent transactions, which do not provide any privacy protections at all. This is due to shielded addresses lacking certain features (such as multi-signature wallets) and the hardware requirements to generate a shielded transaction (a copy of the blockchain and ~3GB of RAM<ref>https://speed.z.cash/</ref>). It is thus possible to correlate transactions when a transparent address sends a given amount to a shielded address and later that amount is transferred to a transparent address. What was private can now be inferred through indirect knowledge thanks to knowing the "inputs and outputs."

It is also possible for a network adversary observing IP addresses to correlate transactions. [[Virtual private network|VPN]]<nowiki/>s, [[Tor (anonymity network)|Tor]], and [[I2P]] can be used to hide IP addresses and there are ongoing efforts to enable Tor by default.

Zcash supports "selective disclosure" capabilities, which allow a user to optionally prove that transactions have occurred or reveal keys that permit their transactions to be viewed by another party. One motivation for such features is to allow users to more easily, and voluntarily, comply with anti-money laundering or tax regulations. That is, "transactions are auditable but disclosure is under the participants' control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=October 31, 2016|language=en}}</ref> Zooko Wilcox, Zcash's founder, has hosted virtual meetings with law enforcement agencies around the U.S to explain these fundamentals. Wilcox has gone on record saying that "they did not develop the currency to facilitate illegal activity".<ref>{{cite news|last1=Popper|first1=Nathaniel|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|work=The New York Times|date=31 October 2016}}</ref>

=== Parameter generation ===
Zcash differs from most cryptocurrencies in that the monetary base required the generation of parameters that could be abused to counterfeit Zcash if "toxic waste" created in the process was not destroyed. A compromise of the "toxic waste" would not impact the anonymity or security of individual transactions, it would only allow for secret inflation.

This threat was mitigated by using a multi-party system in which six individuals would have had to collaborate to manipulate the currency. The participants involved both Zooko (CEO of the company behind Zcash) and Bitcoin core developer Peter Todd, a noted Zcash critic.<ref>{{Cite web|url=https://petertodd.org/2016/cypherpunk-desert-bus-zcash-trusted-setup-ceremony|title=Cypherpunk Desert Bus: My Role In The 2016 Zcash Trusted Setup Ceremony|last=Todd|first=Peter|date=Nov 14, 2016|website=|access-date=}}</ref> Zooko's ceremony was also observed by reporters and three of the participants filmed. All parameter generation took place on new hardware that was disconnected from the internet, with communication to a coordinating server taking place using write-once DVDs. The DVDs were archived and hashes of their contents published online.<ref>{{Cite web|url=https://z.cash/technology/paramgen.html|title=Parameter Generation|last=|first=|date=|website=|access-date=}}</ref>{{Infobox software
| name = Zcash
| logo = File:Zcash-logo-black.png
| logo alt =
| logo caption =
| screenshot = 
| screenshot alt =
| caption =
| collapsible = 
| author =
| developer = [[Zerocoin Electric Coin Company]] (ZECC)
| released = {{Start date and age|df=yes|2016|09|09}}
| discontinued = 
| ver layout = 
| latest release version =1.0.9
| latest release date = 
| latest preview version =
| latest preview date = 
| repo = {{url|https://github.com/zcash/zcash}}
| status = Active
| programming language = C++,<ref>https://github.com/zcash/zcash/tree/master/src</ref> Rust
| operating system = [[GNU/Linux]]
| platform =
| size =
| language =
| language count = 
| language footnote =
| genre = [[Anonymous Internet banking|Anonymous]] [[cryptocurrency]]
| license = [[MIT License]]
| alexa =
| website = 
| standard =
| AsOf =
}}

==History==
Starting in 2014, the protocol that would become Zcash, at that point known as "Zerocash", was developed through a collaboration between the original [[Zerocoin]] researchers at [[Johns Hopkins University]] and a group of cryptographers at the [[Massachusetts Institute of Technology]], the [[Technion – Israel Institute of Technology]], and [[Tel Aviv University]]. Zerocash was an evolution of the existing Zerocoin project — the work of Matthew Green, Ian Miers, Christina Garman, Aviel D. Rubin, at The Johns Hopkins University Department of Computer Science, Baltimore. Together these researchers were able to improve upon the design of Zerocoin by making it more efficient and more private.<ref>{{Cite book|url=http://zerocash-project.org/media/pdf/zerocash-extended-20140518.pdf|title=Zerocash: Decentralized Anonymous Payments from Bitcoin (extended version)|last=Eli|first=Ben-Sasson|publisher=|year=2014|isbn=|location=|pages=}}</ref>

The Zcash project, to implement Zerocash as a production cryptocurrency, was formally announced by ZECC CEO [[Zooko Wilcox]] on Jan 20, 2016.

{{quote|"With the new Zerocash protocol, unlike the old Zerocoin protocol, users can make direct payments to each other with a vastly more efficient cryptographic protocol that also hides the amount of the payment, not just its origin."}} This new protocol by Eli Ben-Sasson, Alessandro Chiesa, Christina Garman, Matthew Green, Ian Miers, Eran Tromer, and Madars Virza produced a coin which would no longer be an “Add-On” to the original Bitcoin but instead would be a new full-fledged digital currency.

Further refinements to the protocol, described in the Zcash protocol specification, were made by Zcash project members.<ref>{{Cite web|url=https://github.com/zcash/zips/blob/master/protocol/protocol.pdf|title=Zcash protocol specification - Version 2017.0-beta-2.7|accessdate=2017-08-07|author=Daira Hopwood, Sean Bowe, Taylor Hornby, Nathan Wilcox|date=2017-07-10|publisher=Zcash Company}}</ref> These included simplifications, functionality improvements, and several security fixes, including a fix to a critical security vulnerability in the instantiation of the Zerocash coin commitment scheme that if uncorrected, would have allowed forgery of coins.<ref>{{Cite web|url=https://z.cash/blog/fixing-zcash-vulns.html|title=Fixing Vulnerabilities in the Zcash Protocol|accessdate=2017-08-07|author=Taylor Hornby, Zooko Wilcox|date=2016-04-26|publisher=Zcash Company}}</ref>

The first mining of ZEC was at 17:10 London Time with the release of the 1.0.0 "Sprout" release on October 28, 2016.<ref>{{Cite web|url=https://z.cash/blog/zcash-launch-and-roadmap.html|title=Zcash Launch and Roadmap|accessdate=2016-10-09|author=Nathan Wilcox|date=2016-08-15|publisher=}}</ref><ref>{{Cite web|url=https://twitter.com/zcashco/status/766055061134843904|title=Zcash is set to launch Oct 28, 2016|accessdate=2016-10-09|author=Zcash Company|date=2016-08-18|publisher=Twitter}}</ref>

In April 2017, Zcash was included among the cryptocurrencies that can be managed by Jaxx, a wallet platform available for [[Android (operating system)|Android]] and [[iOS]].<ref>{{Cite news|url=https://cointelegraph.com/news/apple-accepts-zcash-as-legitimate-cryptocurrency-now-available-on-ios|title=Apple Accepts Zcash as Legitimate Cryptocurrency, Now Available on iOS|last=|first=|date=|work=|access-date=}}</ref>

On April 4th 2017, Zcash entered the top 10 cryptocurrencies by market cap.<ref>http://www.coindesk.com/zcash-enters-top-10-cryptocurrencies-market-cap/</ref>

== Zcash mining ==

Currently Zcash mining is possible via GPU and CPU. Zcash remains resistant against mining with [[Application-specific integrated circuit|ASIC]]-based mining circuits, because of the Equihash [[Algorithm]].<ref>https://z.cash/blog/why-equihash.html</ref> See [https://en.wikibooks.org/w/index.php?title=ZCash_mining_GPU_Comparison&stable=0&redirect=no Wikibooks] for hardware information.

==Legality==
{{see also|Legality of bitcoin by country}}

== See also ==

{{Div col}}
* [[SNARK|zk-SNARKs]]
* [[Zerocoin]]
{{Div col end}}

== References ==
{{Reflist|30em}}

==External links==
* [https://z.cash/ Official website]
* [https://z.cash/support/ Support] (chat, wiki, forum, CVS, etc.)
* [https://explorer.zcha.in/ Zchain]
* [http://blog.coinfabrik.com/zk-snarks-explained-basic-principles/ Zcash Explained]

{{Cryptocurrencies}}
{{Authority control}}

{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]

Zcash

2017-09-05T17:55:41Z

Retimuko: Undid revision 799105449 by Special:Contributions/2001:4649:3A3:0:B503:2AF6:76F8:EDC2 vandalism

{{about-distinguish|the cryptocurrency Zcash|Zerocoin}}
{{refimprove|date=October 2016}}
{{Use dmy dates|date=February 2016}}
{{Infobox currency
| image_1 = File:Zcash-logo-black.png
| image_title_1 = Zcash logo
| date_of_introduction = {{Start date and age|df=yes|2016|10|28}}
| using_countries = Worldwide
| inflation_title = [[Monetary inflation|Supply growth]]
| inflation_rate =
| inflation_source_date =
| iso_code = ZEC{{efn|Unofficial.|group=infobox}}
| footnotes = {{notelist|group=infobox}}
}}


'''Zcash''' is a [[cryptocurrency]] that offers privacy and selective transparency of transactions. Zcash payments are published on a public blockchain, but the sender, recipient, and amount of a transaction may remain private.<ref>{{Cite web|url=https://news.bitcoin.com/snowden-zcash-bitcoin-risks/|title=Snowden: Anonymous 'Zcash' Could Solve Bitcoin Surveillance Risks|accessdate=2016-10-08|author=Jon Southurst|date=2016-06-07|publisher=Bitcoin.com}}</ref><ref>{{Cite web|url=https://z.cash/about.html|title=Zcash - About|accessdate=2016-10-08|quote=Zcash is a decentralized and open-source cryptocurrency that offers both private and transparent transaction types. Zcash payments are published on a public blockchain, but the sender, recipient, and amount of a transaction remain private.}}</ref> The Zcash trade symbol, ZEC, is not an official [[ISO 4217#Cryptocurrencies|ISO 4217]]. Like Bitcoin, Zcash has a fixed total supply of 21 million units.<ref>{{Cite news|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|last=Popper|first=Nathaniel|date=2016-10-31|newspaper=The New York Times|issn=0362-4331|access-date=2017-01-26}}</ref>
{{TOC limit|3}}

== Technology ==

===Privacy===

==== Comparison ====
On traditional blockchains such as [[Bitcoin]] and [[Ethereum]], every entry into the blockchain reveals both the amount of the transaction and the parties involved in the transaction. Bitcoin's [[CoinJoin]] obfuscates the amounts and recipients by allowing users to pool transactions together. It does not hide the total amount value of the pooled transactions, only how the total amount is split between future transactions. It also requires active participation between clients.

[[Bitshares|BitShares]] 1.0 featured the ability to hide the total transaction amount, but not the receiver and recipient of the transaction. However, total transaction amounts can leak by checking the values of previous and future transactions.<ref>{{Cite web|url=https://bytemaster.github.io/article/2014/12/23/How-to-Maintain-Privacy-with-BitShares/ |title=How to Maintain Privacy with BitShares |last=Larimer |first=Daniel |date=2014-12-03 |website=Bytemaster's Blog |archive-url=https://archive.fo/20170512081620/https://bytemaster.github.io/article/2014/12/23/How-to-Maintain-Privacy-with-BitShares/%23 |archive-date=12 May 2017 |dead-url=yes |access-date= |df= }}</ref> [[Monero (cryptocurrency)|Monero]] goes a step further in creating a large number of dummy inputs and outputs for each transaction, creating a much larger set of addresses connected to a given transaction. This too can leak information as clients must create dummy transactions that mimic real transactions. Between April 2014 and January 2017, 62% of all Monero transactions were linkable due to client software creating dummy inputs to transactions from wallets without any balance. Other patterns leaked information about 90% of transactions.<ref>{{cite arxiv|last=Miller|first=Andrew|date=April 2017|title=An Empirical Analysis of Linkability in the Monero Blockchain|eprint=1704.04299}}</ref>

==== Zcash ====
Zcash uses novel cryptographic zero-knowledge proofs ([[SNARK|zk-SNARKs]]) to protect both amount and recipient on special, "shielded" transactions. This increases the set of potential inputs and outputs for a given shielded transaction, to potentially every shielded address on the Zcash blockchain that an adversary cannot exclude via other sources of information.<ref>{{Cite web|url=https://z.cash/blog/anatomy-of-zcash.html|title=Anatomy of A Zcash Transaction|last=|first=|date=Nov 23, 2016|website=|access-date=}}</ref> Although the probability of a shielded input corresponding to any previous shielded output is not uniform (for example, older addresses are less likely to be in use), no information about this is leaked by the transaction itself, other than what can be inferred from timing and metadata (number of shielded transfers, etc). In principle, this is as large as the anonymity set for any public blockchain can become, as a transaction must be recorded.

Zcash also allows for transparent transactions, which do not provide any privacy protections at all. This is due to shielded addresses lacking certain features (such as multi-signature wallets) and the hardware requirements to generate a shielded transaction (a copy of the blockchain and ~3GB of RAM<ref>https://speed.z.cash/</ref>). It is thus possible to correlate transactions when a transparent address sends a given amount to a shielded address and later that amount is transferred to a transparent address. What was private can now be inferred through indirect knowledge thanks to knowing the "inputs and outputs."

It is also possible for a network adversary observing IP addresses to correlate transactions. [[Virtual private network|VPN]]<nowiki/>s, [[Tor (anonymity network)|Tor]], and [[I2P]] can be used to hide IP addresses and there are ongoing efforts to enable Tor by default.

Zcash supports "selective disclosure" capabilities, which allow a user to optionally prove that transactions have occurred or reveal keys that permit their transactions to be viewed by another party. One motivation for such features is to allow users to more easily, and voluntarily, comply with anti-money laundering or tax regulations. That is, "transactions are auditable but disclosure is under the participants' control."<ref>{{cite news|last1=Clozel|first1=Lalita|title=How Zcash Tries to Balance Privacy, Transparency in Blockchain|url=https://www.americanbanker.com/news/how-zcash-tries-to-balance-privacy-transparency-in-blockchain|work=American Banker|date=October 31 2016|language=en}}</ref> Zooko Wilcox, Zcash's founder, has hosted virtual meetings with law enforcement agencies around the U.S to explain these fundamentals. Wilcox has gone on record saying that "they did not develop the currency to facilitate illegal activity".<ref>{{cite news|last1=Popper|first1=Nathaniel|title=Zcash, a Harder-to-Trace Virtual Currency, Generates Price Frenzy|url=https://www.nytimes.com/2016/11/01/business/dealbook/zcash-a-harder-to-trace-virtual-currency-generates-price-frenzy.html|work=The New York Times|date=31 October 2016}}</ref>

=== Parameter generation ===
Zcash differs from most cryptocurrencies in that the monetary base required the generation of parameters that could be abused to counterfeit Zcash if "toxic waste" created in the process was not destroyed. A compromise of the "toxic waste" would not impact the anonymity or security of individual transactions, it would only allow for secret inflation.

This threat was mitigated by using a multi-party system in which six individuals would have had to collaborate to manipulate the currency. The participants involved both Zooko (CEO of the company behind Zcash) and Bitcoin core developer Peter Todd, a noted Zcash critic.<ref>{{Cite web|url=https://petertodd.org/2016/cypherpunk-desert-bus-zcash-trusted-setup-ceremony|title=Cypherpunk Desert Bus: My Role In The 2016 Zcash Trusted Setup Ceremony|last=Todd|first=Peter|date=Nov 14, 2016|website=|access-date=}}</ref> Zooko's ceremony was also observed by reporters and three of the participants filmed. All parameter generation took place on new hardware that was disconnected from the internet, with communication to a coordinating server taking place using write-once DVDs. The DVDs were archived and hashes of their contents published online.<ref>{{Cite web|url=https://z.cash/technology/paramgen.html|title=Parameter Generation|last=|first=|date=|website=|access-date=}}</ref>{{Infobox software
| name = Zcash
| logo = File:Zcash-logo-black.png
| logo alt =
| logo caption =
| screenshot = 
| screenshot alt =
| caption =
| collapsible = 
| author =
| developer = [[Zerocoin Electric Coin Company]] (ZECC)
| released = {{Start date and age|df=yes|2016|09|09}}
| discontinued = 
| ver layout = 
| latest release version =1.0.9
| latest release date = 
| latest preview version =
| latest preview date = 
| repo = {{url|https://github.com/zcash/zcash}}
| status = Active
| programming language = C++,<ref>https://github.com/zcash/zcash/tree/master/src</ref> Rust
| operating system = [[GNU/Linux]]
| platform =
| size =
| language =
| language count = 
| language footnote =
| genre = [[Anonymous Internet banking|Anonymous]] [[cryptocurrency]]
| license = [[MIT License]]
| alexa =
| website = 
| standard =
| AsOf =
}}

==History==
Starting in 2014, the protocol that would become Zcash, at that point known as "Zerocash", was developed through a collaboration between the original [[Zerocoin]] researchers at [[Johns Hopkins University]] and a group of cryptographers at the [[Massachusetts Institute of Technology]], the [[Technion – Israel Institute of Technology]], and [[Tel Aviv University]]. Zerocash was an evolution of the existing Zerocoin project — the work of Matthew Green, Ian Miers, Christina Garman, Aviel D. Rubin, at The Johns Hopkins University Department of Computer Science, Baltimore. Together these researchers were able to improve upon the design of Zerocoin by making it more efficient and more private.<ref>{{Cite book|url=http://zerocash-project.org/media/pdf/zerocash-extended-20140518.pdf|title=Zerocash: Decentralized Anonymous Payments from Bitcoin (extended version)|last=Eli|first=Ben-Sasson|publisher=|year=2014|isbn=|location=|pages=}}</ref>

The Zcash project, to implement Zerocash as a production cryptocurrency, was formally announced by ZECC CEO [[Zooko Wilcox]] on Jan 20, 2016.

{{quote|"With the new Zerocash protocol, unlike the old Zerocoin protocol, users can make direct payments to each other with a vastly more efficient cryptographic protocol that also hides the amount of the payment, not just its origin."}} This new protocol by Eli Ben-Sasson, Alessandro Chiesa, Christina Garman, Matthew Green, Ian Miers, Eran Tromer, and Madars Virza produced a coin which would no longer be an “Add-On” to the original Bitcoin but instead would be a new full-fledged digital currency.

Further refinements to the protocol, described in the Zcash protocol specification, were made by Zcash project members.<ref>{{Cite web|url=https://github.com/zcash/zips/blob/master/protocol/protocol.pdf|title=Zcash protocol specification - Version 2017.0-beta-2.7|accessdate=2017-08-07|author=Daira Hopwood, Sean Bowe, Taylor Hornby, Nathan Wilcox|date=2017-07-10|publisher=Zcash Company}}</ref> These included simplifications, functionality improvements, and several security fixes, including a fix to a critical security vulnerability in the instantiation of the Zerocash coin commitment scheme that if uncorrected, would have allowed forgery of coins.<ref>{{Cite web|url=https://z.cash/blog/fixing-zcash-vulns.html|title=Fixing Vulnerabilities in the Zcash Protocol|accessdate=2017-08-07|author=Taylor Hornby, Zooko Wilcox|date=2016-04-26|publisher=Zcash Company}}</ref>

The first mining of ZEC was at 17:10 London Time with the release of the 1.0.0 "Sprout" release on October 28, 2016.<ref>{{Cite web|url=https://z.cash/blog/zcash-launch-and-roadmap.html|title=Zcash Launch and Roadmap|accessdate=2016-10-09|author=Nathan Wilcox|date=2016-08-15|publisher=}}</ref><ref>{{Cite web|url=https://twitter.com/zcashco/status/766055061134843904|title=Zcash is set to launch Oct 28, 2016|accessdate=2016-10-09|author=Zcash Company|date=2016-08-18|publisher=Twitter}}</ref>

In April 2017, Zcash was included among the cryptocurrencies that can be managed by Jaxx, a wallet platform available for [[Android (operating system)|Android]] and [[iOS]].<ref>{{Cite news|url=https://cointelegraph.com/news/apple-accepts-zcash-as-legitimate-cryptocurrency-now-available-on-ios|title=Apple Accepts Zcash as Legitimate Cryptocurrency, Now Available on iOS|last=|first=|date=|work=|access-date=}}</ref>

On April 4th 2017, Zcash entered the top 10 cryptocurrencies by market cap.<ref>http://www.coindesk.com/zcash-enters-top-10-cryptocurrencies-market-cap/</ref>

== Zcash mining ==

Currently Zcash mining is possible via GPU and CPU. Zcash remains resistant against mining with [[Application-specific integrated circuit|ASIC]]-based mining circuits, because of the Equihash [[Algorithm]].<ref>https://z.cash/blog/why-equihash.html</ref> See [https://en.wikibooks.org/w/index.php?title=ZCash_mining_GPU_Comparison&stable=0&redirect=no Wikibooks] for hardware information.

==Legality==
{{see also|Legality of bitcoin by country}}

== See also ==

{{Div col}}
* [[SNARK|zk-SNARKs]]
* [[Zerocoin]]
{{Div col end}}

== References ==
{{Reflist|30em}}

==External links==
* [https://z.cash/ Official website]
* [https://z.cash/support/ Support] (chat, wiki, forum, CVS, etc.)
* [https://explorer.zcha.in/ Zchain]
* [http://blog.coinfabrik.com/zk-snarks-explained-basic-principles/ Zcash Explained]

{{Cryptocurrencies}}
{{Authority control}}

{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}}

[[Category:Cryptocurrencies]]
[[Category:Application layer protocols]]
[[Category:Software using the MIT license]]
[[Category:Cryptography]]
[[Category:Private currencies]]