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.