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=head1 NAME |
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Crypt::Spritz - Crypt::CBC compliant Spritz encryption/hash/mac/aead/prng module |
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=head1 SYNOPSIS |
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use Crypt::Spritz; |
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# keysize() is 32, but spritz accepts any key size |
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# blocksize() is 16, but cna be anything |
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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 spritz spongelike function. |
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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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package Crypt::Spritz; |
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use XSLoader; |
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$VERSION = '0.0'; |
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XSLoader::load __PACKAGE__, $VERSION; |
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@Crypt::Spritz::CipherBase::ISA = |
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@Crypt::Spritz::Hash::ISA = |
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@Crypt::Spritz::PRNG::ISA = Crypt::Spritz::; |
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@Crypt::Spritz::MAC::ISA = Crypt::Spritz::Hash::; |
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@Crypt::Spritz::Cipher::XOR::ISA = |
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@Crypt::Spritz::Cipher::ISA = |
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@Crypt::Spritz::AEAD::ISA = |
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@Crypt::Spritz::AEAD::XOR::ISA = Crypt::Spritz::CipherBase::; |
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sub Crypt::Spritz::CipherBase::keysize () { 32 } |
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sub Crypt::Spritz::CipherBase::blocksize () { 64 } |
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*Crypt::Spritz::Hash::add = |
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*Crypt::Spritz::PRNG::add = \&Crypt::Spritz::absorb; |
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*Crypt::Spritz::PRNG::get = \&Crypt::Spritz::squeeze; |
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*Crypt::Spritz::AEAD::XOR::finish = |
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*Crypt::Spritz::AEAD::finish = \&Crypt::Spritz::Hash::finish; |
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*Crypt::Spritz::AEAD::XOR::associated_data = |
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*Crypt::Spritz::AEAD::associated_data = |
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*Crypt::Spritz::AEAD::XOR::nonce = |
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*Crypt::Spritz::AEAD::nonce = \&Crypt::Spritz::absborb_and_stop; |
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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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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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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<Digest::HMAC>, L<http://people.csail.mit.edu/rivest/pubs/RS14.pdf>. |
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=head1 SECURITY CONSIDERATIONS |
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I also cannot guarantee for security. |
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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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