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.\" ========================================================================
.\"
.IX Title "CAST5 3pm"
.TH CAST5 3pm "2012-02-10" "perl v5.24.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.SH "NAME"
Crypt::CAST5 \- CAST5 block cipher
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    use Crypt::CBC;
\&
\&    my $crypt = Crypt::CBC\->new({
\&        key    => "secret key",
\&        cipher => "CAST5",
\&    });
\&
\&    my $message = "All mimsy were the borogoves";
\&    my $ciphertext = $crypt\->encrypt($message);
\&    print unpack("H*", $ciphertext), "\en";
\&
\&    my $plaintext = $crypt\->decrypt($ciphertext);
\&    print $plaintext, "\en";
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module provides an implementation of the \s-1CAST5\s0 block cipher using
compiled C code for increased speed. \s-1CAST5\s0 is also known as \s-1CAST\-128.\s0 It
is a product of the \s-1CAST\s0 design procedure developed by C. Adams and
S. Tavares.
.PP
The \s-1CAST5\s0 cipher is available royalty-free.
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
.SS "blocksize"
.IX Subsection "blocksize"
Returns the \s-1CAST5\s0 block size, which is 8 bytes. This function exists
so that Crypt::CAST5 can work with Crypt::CBC.
.SS "keysize"
.IX Subsection "keysize"
Returns the maximum \s-1CAST5\s0 key size, 16 bytes.
.SS "new"
.IX Subsection "new"
.Vb 1
\&    $cast5 = Crypt::CAST5\->new($key);
.Ve
.PP
Create a new encryption object. If the optional key parameter is given,
it will be passed to the \fIinit()\fR function.
.SS "init"
.IX Subsection "init"
.Vb 1
\&    $cast5\->init($key);
.Ve
.PP
Set or change the encryption key to be used. The key must be from 40 bits
(5 bytes) to 128 bits (16 bytes) in length. Note that if the key used is
80 bits or less, encryption and decryption will be somewhat faster.
.PP
It is best for the key to be random binary data, not something printable
like a password. A message digest function may be useful for converting
a password to an encryption key; see Digest::SHA1 or Digest::MD5.
Note that Crypt::CBC runs the given \*(L"key\*(R" through \s-1MD5\s0 to get the actual
encryption key.
.SS "encrypt"
.IX Subsection "encrypt"
.Vb 1
\&    $ciphertext = $cast5\->encrypt($plaintext);
.Ve
.PP
Encrypt a block of plaintext using the current encryption key, and return
the corresponding ciphertext. The input must be 8 bytes long, and the output
has the same length. Note that the encryption is in \s-1ECB\s0 mode, which means
that it encrypts each block independently. That can leave you vulnerable
to dictionary attacks, so it is generally best to use some form of chaining
between blocks; see Crypt::CBC.
.SS "decrypt"
.IX Subsection "decrypt"
.Vb 1
\&    $plaintext = $cast5\->decrypt($ciphertext);
.Ve
.PP
Decrypt the ciphertext and return the corresponding plaintext.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1RFC 2144, \s0\*(L"The \s-1CAST\-128\s0 Encryption Algorithm\*(R", C. Adams, May 1997
.PP
Crypt::CBC
.SH "AUTHOR"
.IX Header "AUTHOR"
Bob Mathews, <bobmathews@alumni.calpoly.edu>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
Copyright (C) 2002\-2006 Bob Mathews
.PP
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.