NAME

Crypt::Eksblowfish::Blowfish - Blowfish block cipher via Eksblowfish engine

SYNOPSIS

use Crypt::Eksblowfish::Blowfish;

$block_size = Crypt::Eksblowfish::Blowfish->blocksize;
$key_size = Crypt::Eksblowfish::Blowfish->keysize;

$cipher = Crypt::Eksblowfish::Blowfish->new($key);

$block_size = $cipher->blocksize;
$ciphertext = $cipher->encrypt($plaintext);
$plaintext = $cipher->decrypt($ciphertext);

$p_array = $cipher->p_array;
$s_boxes = $cipher->s_boxes;
if($cipher->is_weak) { ...

DESCRIPTION

An object of this type encapsulates a keyed instance of the Blowfish block cipher, ready to encrypt and decrypt.

Blowfish is a symmetric cipher algorithm designed by Bruce Schneier in 1993. It operates on 64-bit blocks, and takes a variable-length key from 32 bits (4 octets) to 448 bits (56 octets) in increments of 8 bits (1 octet).

This implementation of Blowfish uses an encryption engine that was originally implemented in order to support Eksblowfish, which is a variant of Blowfish modified to make keying particularly expensive. See Crypt::Eksblowfish for that variant; this class implements the original Blowfish.

CLASS METHODS

Crypt::Eksblowfish::Blowfish->blocksize

Returns 8, indicating the Blowfish block size of 8 octets. This method may be called on either the class or an instance.

Crypt::Eksblowfish::Blowfish->keysize

Returns 0, indicating that the key size is variable. This situation is handled specially by Crypt::CBC.

CONSTRUCTOR

Crypt::Eksblowfish::Blowfish->new(KEY)

Performs key setup on a new instance of the Blowfish algorithm, returning the keyed state. The KEY may be any length from 4 octets to 56 octets inclusive.

You may occasionally come across an alleged Blowfish key that is outside this length range, and so is rejected by this constructor. Blowfish can internally process a key of any octet length up to 72 octets, and some implementations don't enforce the official length restrictions. If it is necessary for compatibility, a key of out-of-range length can be processed by Crypt::Eksblowfish::Uklblowfish.

METHODS

$cipher->blocksize

Returns 8, indicating the Blowfish block size of 8 octets. This method may be called on either the class or an instance.

$cipher->encrypt(PLAINTEXT)

PLAINTEXT must be exactly eight octets. The block is encrypted, and the ciphertext is returned.

$cipher->decrypt(CIPHERTEXT)

CIPHERTEXT must be exactly eight octets. The block is decrypted, and the plaintext is returned.

$cipher->p_array

$cipher->s_boxes

These methods extract the subkeys from the keyed cipher. This is not required in ordinary operation. See the superclass Crypt::Eksblowfish::Subkeyed for details.

$cipher->is_weak

This method checks whether the cipher has been keyed with a weak key. It may be desired to avoid using weak keys. See the superclass Crypt::Eksblowfish::Subkeyed for details.

SEE ALSO

Crypt::Eksblowfish, Crypt::Eksblowfish::Subkeyed, Crypt::Eksblowfish::Uklblowfish, http://www.schneier.com/blowfish.html

AUTHOR

Eksblowfish guts originally by Solar Designer (solar at openwall.com).

Modifications and Perl interface by Andrew Main (Zefram) <zefram@fysh.org>.

COPYRIGHT

Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Andrew Main (Zefram) <zefram@fysh.org>

The original Eksblowfish code (in the form of crypt()) from which this module is derived is in the public domain. It may be found at http://www.openwall.com/crypt/.

LICENSE

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.