crypt::blowfish(3pm) [debian man page]
Blowfish(3pm) User Contributed Perl Documentation Blowfish(3pm) NAME
Crypt::Blowfish - Perl Blowfish encryption module SYNOPSIS
use Crypt::Blowfish; my $cipher = new Crypt::Blowfish $key; my $ciphertext = $cipher->encrypt($plaintext); my $plaintext = $cipher->decrypt($ciphertext); You probably want to use this in conjunction with a block chaining module like Crypt::CBC. DESCRIPTION
Blowfish is capable of strong encryption and can use key sizes up to 56 bytes (a 448 bit key). You're encouraged to take advantage of the full key size to ensure the strongest encryption possible from this module. Crypt::Blowfish has the following methods: blocksize() keysize() encrypt() decrypt() FUNCTIONS
blocksize Returns the size (in bytes) of the block cipher. Crypt::Blowfish doesn't return a key size due to its ability to use variable-length keys. More accurately, it shouldn't, but it does anyway to play nicely with others. new my $cipher = new Crypt::Blowfish $key; This creates a new Crypt::Blowfish BlockCipher object, using $key, where $key is a key of "keysize()" bytes (minimum of eight bytes). encrypt my $cipher = new Crypt::Blowfish $key; my $ciphertext = $cipher->encrypt($plaintext); This function encrypts $plaintext and returns the $ciphertext where $plaintext and $ciphertext must be of "blocksize()" bytes. (hint: Blowfish is an 8 byte block cipher) decrypt my $cipher = new Crypt::Blowfish $key; my $plaintext = $cipher->decrypt($ciphertext); This function decrypts $ciphertext and returns the $plaintext where $plaintext and $ciphertext must be of "blocksize()" bytes. (hint: see previous hint) EXAMPLE
my $key = pack("H16", "0123456789ABCDEF"); # min. 8 bytes my $cipher = new Crypt::Blowfish $key; my $ciphertext = $cipher->encrypt("plaintex"); # SEE NOTES print unpack("H16", $ciphertext), " "; PLATFORMS
Please see the README document for platforms and performance tests. NOTES
The module is capable of being used with Crypt::CBC. You're encouraged to read the perldoc for Crypt::CBC if you intend to use this module for Cipher Block Chaining modes. In fact, if you have any intentions of encrypting more than eight bytes of data with this, or any other block cipher, you're going to need some type of block chaining help. Crypt::CBC tends to be very good at this. If you're not going to encrypt more than eight bytes, your data must be exactly eight bytes long. If need be, do your own padding. " " as a null byte is perfectly valid to use for this. SEE ALSO
Crypt::CBC, Crypt::DES, Crypt::IDEA Bruce Schneier, Applied Cryptography, 1995, Second Edition, published by John Wiley & Sons, Inc. COPYRIGHT
The implementation of the Blowfish algorithm was developed by, and is copyright of, A.M. Kuchling. Other parts of the perl extension and module are copyright of Systemics Ltd ( http://www.systemics.com/ ). Code revisions, updates, and standalone release are copyright 1999-2010 W3Works, LLC. AUTHOR
Original algorithm, Bruce Shneier. Original implementation, A.M. Kuchling. Original Perl implementation, Systemics Ltd. Current maintenance by W3Works, LLC. Current revision and maintainer: Dave Paris <amused@pobox.com> perl v5.14.2 2010-03-04 Blowfish(3pm)
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Crypt::Eksblowfish::Uklblowfish(3pm) User Contributed Perl Documentation Crypt::Eksblowfish::Uklblowfish(3pm) NAME
Crypt::Eksblowfish::Uklblowfish - Blowfish cipher with unrestricted key length SYNOPSIS
use Crypt::Eksblowfish::Uklblowfish; $block_size = Crypt::Eksblowfish::Uklblowfish->blocksize; $key_size = Crypt::Eksblowfish::Uklblowfish->keysize; $cipher = Crypt::Eksblowfish::Uklblowfish->new($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. However, if you're looking for an implementation of Blowfish you most likely want Crypt::Eksblowfish::Blowfish. This class differs from the standard Blowfish in that it accepts some keys that Blowfish officially does not permit. Blowfish is a symmetric cipher algorithm designed by Bruce Schneier in 1993. It operates on 64-bit blocks, and takes a variable-length key. Officially the key can vary from 32 bits (4 octets) to 448 bits (56 octets) in increments of 8 bits (1 octet). In fact the algorithm can easily operate on a key of any number of octets from 1 (8 bits) to 72 (576 bits). Some implementations don't enforce the official key length limits, and so for compatibility it is sometimes necessary to handle a Blowfish key of a prohibited length. That is what this class is for. The "Ukl" in the name stands for "unrestricted key length". Using a very short key is generally a bad idea because there aren't very many keys of that length and so it's easy for an attacker to try them all. The official 32-bit minimum for Blowfish was already far too short for serious security at the time that Blowfish was designed. (A machine to crack 56-bit DES keys by brute force in a few days each was publicly built only five years later.) Do not base your security on the secrecy of a short key. Using overlong keys has more interesting effects, which depend on internal features of Blowfish. When the key exceeds 64 octets (512 bits), varying key bits past that length results in subkeys which have predictable relationships. There is also some possibility of equivalent keys when the keys exceed 64 octets and differ only in the first 8 octets (64 bits). These phenomena have not been extensively studied in the open literature, so it is difficult to judge the degree of cryptographic weakness that results from them. It is clear that beyond some length Blowfish keys do not have as much strength as their length would suggest, and it is possible that overlong keys have specific weaknesses that render them weaker than shorter keys. If choosing a key for security, it is advised to stay within the official length limit of 56 octets. In summary: using Blowfish keys of officially-unsupported lengths causes security problems. If you are using Blowfish for security, and have the choice, use a key of an officially-supported length (and a standard implementation such as Crypt::Eksblowfish::Blowfish). Use out-of-range key lengths (and this class) only for compatibility or cryptanalytic reasons. CLASS METHODS
Crypt::Eksblowfish::Uklblowfish->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::Uklblowfish->keysize Returns 0, indicating that the key size is variable. This situation is handled specially by "Crypt::CBC". CONSTRUCTOR
Crypt::Eksblowfish::Uklblowfish->new(KEY) Performs key setup on a new instance of the Blowfish algorithm, returning the keyed state. The KEY may be any length from 1 octet to 72 octets inclusive. 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. This method does not detect any cryptographic weaknesses that might result from the related-key properties and other features of overlong keys. SEE ALSO
Crypt::Eksblowfish::Blowfish 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 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. perl v5.14.2 2011-11-15 Crypt::Eksblowfish::Uklblowfish(3pm)