1Crypt::Eksblowfish(3) User Contributed Perl DocumentationCrypt::Eksblowfish(3)
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NAME

6       Crypt::Eksblowfish - the Eksblowfish block cipher
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SYNOPSIS

9               use Crypt::Eksblowfish;
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11               $block_size = Crypt::Eksblowfish->blocksize;
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13               $cipher = Crypt::Eksblowfish->new(8, $salt, $key);
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15               $block_size = $cipher->blocksize;
16               $ciphertext = $cipher->encrypt($plaintext);
17               $plaintext = $cipher->decrypt($ciphertext);
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19               $p_array = $cipher->p_array;
20               $s_boxes = $cipher->s_boxes;
21               if($cipher->is_weak) { ...
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DESCRIPTION

24       An object of this type encapsulates a keyed instance of the Eksblowfish
25       block cipher, ready to encrypt and decrypt.
26
27       Eksblowfish is a variant of the Blowfish cipher, modified to make the
28       key setup very expensive.  ("Eks" stands for "expensive key schedule".)
29       This doesn't make it significantly cryptographically stronger, but is
30       intended to hinder brute-force attacks.  It also makes it unsuitable
31       for any application requiring key agility.  It was designed by Niels
32       Provos and David Mazieres for password hashing in OpenBSD.  See
33       Crypt::Eksblowfish::Bcrypt for the hash algorithm.  See
34       Crypt::Eksblowfish::Blowfish for the unmodified Blowfish cipher.
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36       Eksblowfish is a parameterised (family-keyed) cipher.  It takes a cost
37       parameter that controls how expensive the key scheduling is.  It also
38       takes a family key, known as the "salt".  Cost and salt parameters
39       together define a cipher family.  Within each family, a key determines
40       an encryption function in the usual way.  See
41       Crypt::Eksblowfish::Family for a way to encapsulate an Eksblowfish
42       cipher family.
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CLASS METHODS

45       Crypt::Eksblowfish->blocksize
46           Returns 8, indicating the Eksblowfish block size of 8 octets.  This
47           method may be called on either the class or an instance.
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CONSTRUCTOR

50       Crypt::Eksblowfish->new(COST, SALT, KEY)
51           Performs key setup on a new instance of the Eksblowfish algorithm,
52           returning the keyed state.  The KEY may be any length from 1 octet
53           to 72 octets inclusive.  The SALT is a family key, and must be
54           exactly 16 octets.  COST is an integer parameter controlling the
55           expense of keying: the number of operations in key setup is
56           proportional to 2^COST.  All three parameters influence all the
57           subkeys; changing any of them produces a different encryption
58           function.
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60           Due to the mandatory family-keying parameters (COST and SALT), this
61           constructor does not match the interface expected by "Crypt::CBC"
62           and similar crypto plumbing modules.  To use Eksblowfish with them
63           it is necessary to have an object that encapsulates a cipher family
64           and provides a constructor that takes only a key argument.  That
65           facility is supplied by "Crypt::Eksblowfish::Family".
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METHODS

68       $cipher->blocksize
69           Returns 8, indicating the Eksblowfish block size of 8 octets.  This
70           method may be called on either the class or an instance.
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72       $cipher->encrypt(PLAINTEXT)
73           PLAINTEXT must be exactly eight octets.  The block is encrypted,
74           and the ciphertext is returned.
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76       $cipher->decrypt(CIPHERTEXT)
77           CIPHERTEXT must be exactly eight octets.  The block is decrypted,
78           and the plaintext is returned.
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80       $cipher->p_array
81       $cipher->s_boxes
82           These methods extract the subkeys from the keyed cipher.  This is
83           not required in ordinary operation.  See the superclass
84           Crypt::Eksblowfish::Subkeyed for details.
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86       $cipher->is_weak
87           This method checks whether the cipher has been keyed with a weak
88           key.  It may be desired to avoid using weak keys.  See the
89           superclass Crypt::Eksblowfish::Subkeyed for details.
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SEE ALSO

92       Crypt::Eksblowfish::Bcrypt, Crypt::Eksblowfish::Blowfish,
93       Crypt::Eksblowfish::Family, Crypt::Eksblowfish::Subkeyed,
94       <http://www.usenix.org/events/usenix99/provos/provos_html/node4.html>
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AUTHOR

97       Eksblowfish guts originally by Solar Designer (solar at openwall.com).
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99       Modifications and Perl interface by Andrew Main (Zefram)
100       <zefram@fysh.org>.
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103       Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Andrew Main (Zefram)
104       <zefram@fysh.org>
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106       The original Eksblowfish code (in the form of crypt()) from which this
107       module is derived is in the public domain.  It may be found at
108       <http://www.openwall.com/crypt/>.
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LICENSE

111       This module is free software; you can redistribute it and/or modify it
112       under the same terms as Perl itself.
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116perl v5.12.3                      2011-04-30             Crypt::Eksblowfish(3)
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