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=head1 NAME |
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Crypt::Twofish2 - Crypt::CBC compliant Twofish encryption module |
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=head1 SYNOPSIS |
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use Crypt::Twofish2; |
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# keysize() is 32, but 24 and 16 are also possible |
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# blocksize() is 16 |
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$cipher = new Crypt::Twofish2 "a" x 32, Crypt::Twofish2::MODE_CBC; |
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$crypted = $cipher->encrypt($plaintext); |
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# - OR - |
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$plaintext = $cipher->decrypt($crypted); |
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=head1 DESCRIPTION |
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This module implements the twofish cipher in a less braindamaged (read: |
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slow and ugly) way than the existing C<Crypt::Twofish> module. |
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Although it is C<Crypt::CBC> compliant you usually gain nothing by using |
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that module (except generality, which is often a good thing), since |
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C<Crypt::Twofish2> can work in either ECB or CBC mode itself. |
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=over 4 |
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=cut |
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|
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package Crypt::Twofish2; |
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use XSLoader; |
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$VERSION = '1.03'; |
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XSLoader::load __PACKAGE__, $VERSION; |
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=item keysize |
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Returns the keysize, which is 32 (bytes). The Twofish2 cipher actually |
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supports keylengths of 16, 24 or 32 bytes, but there is no way to |
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communicate this to C<Crypt::CBC>. |
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=item blocksize |
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The blocksize for Twofish2 is 16 bytes (128 bits), which is somewhat |
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unique. It is also the reason I need this module myself ;) |
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=item $cipher = new $key [, $mode] |
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Create a new C<Crypt::Twofish2> cipher object with the given key (which |
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must be 128, 192 or 256 bits long). The additional C<$mode> argument is |
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the encryption mode, either C<MODE_ECB> (electronic cookbook mode, the |
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default), C<MODE_CBC> (cipher block chaining, the same that C<Crypt::CBC> |
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does) or C<MODE_CFB1> (1-bit cipher feedback mode). |
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|
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ECB mode is very insecure (read a book on cryptography if you don't know |
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why!), so you should probably use CBC mode. CFB1 mode is not tested and is |
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most probably broken, so do not try to use it. |
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|
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In ECB mode you can use the same cipher object to encrypt and decrypt |
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data. However, every change of "direction" causes an internal reordering |
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of key data, which is quite slow, so if you want ECB mode and |
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encryption/decryption at the same time you should create two seperate |
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C<Crypt::Twofish2> objects with the same key. |
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In CBC mode you have to use seperate objects for encryption/decryption in |
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any case. |
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The C<MODE_*>-constants are not exported by this module, so you must |
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specify them as C<Crypt::Twofish2::MODE_CBC> etc. (sorry for that). |
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=item $cipher->encrypt($data) |
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Encrypt data. The size of C<$data> must be a multiple of C<blocksize> (16 |
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bytes), otherwise this function will croak. Apart from that, it can be of |
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(almost) any length. |
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=item $cipher->decrypt($data) |
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The pendant to C<encrypt> in that it I<de>crypts data again. |
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=back |
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=head1 SEE ALSO |
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L<Crypt::CBC>, L<Crypt::Twofish>. |
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=head1 BUGS |
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Should EXPORT or EXPORT_OK the MODE constants. |
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There should be a way to access initial IV contents :( |
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Although I tried to make the original twofish code portable, I can't say |
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how much I did succeed. The code tries to be portable itself, and I hope |
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I got the endianness issues right. The code is also copyright Counterpane |
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Systems, no license accompanied it, so using it might actually be illegal |
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;) |
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I also cannot guarantee for security, but the module is used quite a bit, |
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so there are no obvious bugs left. |
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=head1 AUTHOR |
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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The actual twofish encryption is written in horribly microsoft'ish looking |
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almost ansi-c by Doug Whiting. |
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=cut |
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1; |
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