Encryption on Linux

Cryptography on Linux has long been established, but lacks in consistency.

While the (end)user wants to encrypt a file or a filesystem (harddisk partition or flash memory card or CD/DVD disk) and wants to be sure, that after his next upgrade of kernel or distribution his data is still readable.

An immense amount of documentation can be found on the Internet about linux encryption, but hardly ever it documents, under which circumstances the software works. The almost infinite amount of combinations of kernel, util-linux, which includes the losetup program, plus all the patches that exist for above, makes it close to impossible to guarantee the above goal.

Software

The following software can be used on linux to encrypt a file or filesystem. This document aims to tell you precisely which software works on which version of your operating system.

• losetup and cryptoloop, part of 2.6.x kernel and util-linux
• aespipe, program to encrypt a file stream with the AES algorithm with key lengths 128, 192 and 256 bit
• DM Crypt
• cryptoloop
• Loop AES
• Crypt Mount
• eCryptFS

It is not clear, which of the encrypted files of the above software are compatible to each other, even they seem to use the same AES algorithm.

Distributions

As different linux distributions are packaged with different software, the setup of encryption varies. This document aims to guide you to the right direction for your distribution, as far as encryption software is provided in it. Please note that memory cards and harddisk partitions are encrypted and used equally.

Distribution	Packages needed	Encrypt file	Encrypt partition	Encrypt CD/DVD
Fedora Core 5	LUKS, cryptsetup	cryptsetup	cryptsetup	???
Suse 10	???	???	???	???
Debian Sarge	cryptsetup	losetup/cryptsetup	cryptsetup	not possible (aespipe needed)
Debian Etch	cryptsetup	losetup/cryptsetup	cryptsetup	not possible (aespipe needed)