NAME

aesget —

decrypt data using Rijndael, the Advanced Encryption Standard winner

SYNOPSIS

aesget -k keyfile [-s keysize]

DESCRIPTION

The aesget utility decrypts data using the Rijndael algorithm, the winner of the Advanced Encryption Standard (AES) competition. The decryption is done in Cipher Block Feedback (CFB-128) mode, with the salt read from the first 128 bits (16 bytes) of the encrypted data as generated by the aescrypt(1) utility. The encrypted data (including the salt) is read from standard input and the decrypted plaintext is written to standard output.

The decryption key may be read from standard input or from a file, depending on the argument passed to the -k command-line option. If “-” is used as a filename, the aesget utility reads as many hexadecimal digits as needed from standard input and then one additional byte to allow for a newline separating the key from the actual data to be decrypted. If the filename is not “-”, the aesget utility opens the specified file and reads text lines from it until a line starting with the characters kk= is reached. Those characters should be immediately followed by as many hexadecimal digits as needed; the rest of the line, as well as the rest of the file, is ignored.

The decryption key may be 128, 192, or 256 bits long. By default, the aesget utility uses (and expects to read) a 128-bit key, unless a different size is supplied by the -s keysize command-line option.

EXAMPLES

Decrypt the contents of the /etc/hosts file with a key (128-bit by default) read from a file:

aesget -k key.txt < hosts.aes >
  hosts.txt

Decrypt a file with a 192-bit key supplied directly:

(echo
  '012345678901234567890123456789012345678901234567'; cat test.aes) | ./aesget
  -s 192 -k -

HISTORY

The aesget utility was written by Eric Lee Green, and was modified to use Rijndael rather than Twofish by Randy Kaelber. It uses the freely available Rijndael implementation by Antoon Bosselaers and Vincent Rijmen. This manual page was written by Peter Pentchev in 2008.

AUTHORS

The aesget utility - Eric Lee Green ⟨eric@badtux.org⟩, Randy Kaelber ⟨randyk@sourceforge.net⟩.

The manual page - Peter Pentchev ⟨roam@ringlet.net⟩.