Talk:Simple file verification

Computing Stub‑class

	This article is within the scope of WikiProject Computing, a collaborative effort to improve the coverage of computers, computing, and information technology on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.ComputingWikipedia:WikiProject ComputingTemplate:WikiProject ComputingComputing
Stub	This article has been rated as Stub-class on Wikipedia's content assessment scale.
???	This article has not yet received a rating on the project's importance scale.
	This article has been automatically rated by a bot or other tool as Stub-class because it uses a stub template. Please ensure the assessment is correct before removing the `\|auto=` parameter.

What if all files where transmitted correctly, but not the corresponding SFV file, therefore raising a false-positive transmission error?
What if files got corrupted and so did the SFV file - in such a way that the corrupted checksum happens to be the correct checksum for the corrupted files, therefore passing the files as false-negative valid files?
What if the files were edited maliciously and so was the SFV file to look as if the files were authentic?

So to speak, in its pure form, SFV does neither add to integrity nor authentity of files, at least not as much as this article currently promises. --Abdull 20:13, 26 April 2007 (UTC)[reply]

No user is probably ever going to rely on just a single hashcheck. In fact, most users don't even know what a hash is, and their way of checking a file's integrity is to open it in the program it's made for. And if you have already found out you have your data intact, who cares about the .sfv? Create a new one if you need it.
I'm not saying it's completely impossible, but what are the odds of that actually happening, really?
If you are to use .sfv as a safety check, you are not going to verify the data with the hash in the .sfv that ships with the data, but with the one you got from the "source" (either from a person who was the original owner of the data - or if thats you - from what you wrote down somewhere secure).

The article doesn't promise SFV to be the ultimate integrity & security verification, it merely points out the main use of SFV as a basic integrity and (if used wisely (see point 3), as a bonus) simple security check. Or if at the time of your writing, the page was radically different, you should have provided a diff for that version, or something. -- 82.131.68.159 07:06, 1 June 2007 (UTC)[reply]

Question

Are SFV's also used to combine files downloaded in segments into the 'original' file? —Preceding unsigned comment added by 66.105.208.12 (talk) 07:09, 24 November 2007 (UTC)[reply]

Nope. Only for checking files against corruption or modification. James.Denholm®^{Talk to me...} 09:51, 3 May 2009 (UTC)[reply]

What happens if you have a filename beginning with a semicolon? DancesWithGrues (talk) 01:45, 17 April 2013 (UTC)[reply]

Mac / Unix shell script to check

if you want to check an sfv against the contents of that directory, this shell script will work. (not for the the faint at heart with the command prompt, requires proper line endings -- hence dos2unix at the beginning).

#!/bin/sh
dos2unix *.sfv
cat *.sfv |
{
  read line;
  while [ "$line" != "" ];
    do read line;
    file=`echo $line | cut '-d ' -f1`;
    crc=`echo $line | rev | cut '-d ' -f1 | rev | cut  -f1 `;
    crccheck=`crc32 $file`;
    if [[ "$crccheck" == "$crc" ]];
    then echo "$file			Good.";
    else echo "$file			Bad!! ($crccheck instead of expected $crc)"; exit;
    fi;
  done;
}

While I realize that this can be useful to people, Wikipedia is not the place to simply dump scripts on, and Wikipedia talk pages should be used for discussing improvements to the article. -- intgr [talk] 12:49, 15 November 2007 (UTC)[reply]

Lots of missing info

So is SFV simply a de facto file format or is there a standard algorithm, etc.? If so, who invented it, etc. Ham Pastrami 12:05, 2 December 2007 (UTC)[reply]

The standard algorithm is mentioned in the article, and it's quite common - it is used in the warez scene.--134.147.252.130 (talk) 13:12, 28 August 2008 (UTC)[reply]

The checksum that is used (CRC32) is standard, the file format is not. What exactly do you think is missing? -- intgr [talk] 07:36, 29 August 2008 (UTC)[reply]

CRC can use any polynomial. To be used as a standard, a specific polynomial must be chosen. We are left to guess that CRCs stored in SFV are expected to use a specific polynomial (can this be confirmed?) and it is the same polynomial as IEEE (can this also be confirmed?) since it is probably the most common. Article still hasn't answered my original question of who came up with SFV or how its usage spread, so I've already stated what's missing. Ham Pastrami (talk) 09:26, 20 March 2010 (UTC)[reply]

I guess what *I'm* missing is who uses it. In my world md5sums (and/or SHA) are the norm. The warez scene sounds likely. This is by the way a pretty long-winded article for something that can be explained simply as a "listing of file names and checksums". JöG (talk) 22:25, 12 January 2010 (UTC)[reply]