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Edit File: Crypt::Eksblowfish.3pm
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" Crypt::Eksblowfish \- the Eksblowfish block cipher .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& use Crypt::Eksblowfish; \& \& $block_size = Crypt::Eksblowfish\->blocksize; \& \& $cipher = Crypt::Eksblowfish\->new(8, $salt, $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) { ... .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" An object of this type encapsulates a keyed instance of the Eksblowfish block cipher, ready to encrypt and decrypt. .PP Eksblowfish is a variant of the Blowfish cipher, modified to make the key setup very expensive. (\*(L"Eks\*(R" stands for \*(L"expensive key schedule\*(R".) This doesn't make it significantly cryptographically stronger, but is intended to hinder brute-force attacks. It also makes it unsuitable for any application requiring key agility. It was designed by Niels Provos and David Mazieres for password hashing in OpenBSD. See Crypt::Eksblowfish::Bcrypt for the hash algorithm. See Crypt::Eksblowfish::Blowfish for the unmodified Blowfish cipher. .PP Eksblowfish is a parameterised (family-keyed) cipher. It takes a cost parameter that controls how expensive the key scheduling is. It also takes a family key, known as the \*(L"salt\*(R". Cost and salt parameters together define a cipher family. Within each family, a key determines an encryption function in the usual way. See Crypt::Eksblowfish::Family for a way to encapsulate an Eksblowfish cipher family. .SH "CLASS METHODS" .IX Header "CLASS METHODS" .IP "Crypt::Eksblowfish\->blocksize" 4 .IX Item "Crypt::Eksblowfish->blocksize" Returns 8, indicating the Eksblowfish block size of 8 octets. This method may be called on either the class or an instance. .SH "CONSTRUCTOR" .IX Header "CONSTRUCTOR" .IP "Crypt::Eksblowfish\->new(\s-1COST, SALT, KEY\s0)" 4 .IX Item "Crypt::Eksblowfish->new(COST, SALT, KEY)" Performs key setup on a new instance of the Eksblowfish algorithm, returning the keyed state. The \s-1KEY\s0 may be any length from 1 octet to 72 octets inclusive. The \s-1SALT\s0 is a family key, and must be exactly 16 octets. \s-1COST\s0 is an integer parameter controlling the expense of keying: the number of operations in key setup is proportional to 2^COST. All three parameters influence all the subkeys; changing any of them produces a different encryption function. .Sp Due to the mandatory family-keying parameters (\s-1COST\s0 and \s-1SALT\s0), this constructor does not match the interface expected by \f(CW\*(C`Crypt::CBC\*(C'\fR and similar crypto plumbing modules. To use Eksblowfish with them it is necessary to have an object that encapsulates a cipher family and provides a constructor that takes only a key argument. That facility is supplied by \f(CW\*(C`Crypt::Eksblowfish::Family\*(C'\fR. .SH "METHODS" .IX Header "METHODS" .ie n .IP "$cipher\->blocksize" 4 .el .IP "\f(CW$cipher\fR\->blocksize" 4 .IX Item "$cipher->blocksize" Returns 8, indicating the Eksblowfish block size of 8 octets. This method may be called on either the class or an instance. .ie n .IP "$cipher\->encrypt(\s-1PLAINTEXT\s0)" 4 .el .IP "\f(CW$cipher\fR\->encrypt(\s-1PLAINTEXT\s0)" 4 .IX Item "$cipher->encrypt(PLAINTEXT)" \&\s-1PLAINTEXT\s0 must be exactly eight octets. The block is encrypted, and the ciphertext is returned. .ie n .IP "$cipher\->decrypt(\s-1CIPHERTEXT\s0)" 4 .el .IP "\f(CW$cipher\fR\->decrypt(\s-1CIPHERTEXT\s0)" 4 .IX Item "$cipher->decrypt(CIPHERTEXT)" \&\s-1CIPHERTEXT\s0 must be exactly eight octets. The block is decrypted, and the plaintext is returned. .ie n .IP "$cipher\->p_array" 4 .el .IP "\f(CW$cipher\fR\->p_array" 4 .IX Item "$cipher->p_array" .PD 0 .ie n .IP "$cipher\->s_boxes" 4 .el .IP "\f(CW$cipher\fR\->s_boxes" 4 .IX Item "$cipher->s_boxes" .PD These methods extract the subkeys from the keyed cipher. This is not required in ordinary operation. See the superclass Crypt::Eksblowfish::Subkeyed for details. .ie n .IP "$cipher\->is_weak" 4 .el .IP "\f(CW$cipher\fR\->is_weak" 4 .IX Item "$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. .SH "SEE ALSO" .IX Header "SEE ALSO" Crypt::Eksblowfish::Bcrypt, Crypt::Eksblowfish::Blowfish, Crypt::Eksblowfish::Family, Crypt::Eksblowfish::Subkeyed, <http://www.usenix.org/events/usenix99/provos/provos_html/node4.html> .SH "AUTHOR" .IX Header "AUTHOR" Eksblowfish guts originally by Solar Designer (solar at openwall.com). .PP Modifications and Perl interface by Andrew Main (Zefram) <zefram@fysh.org>. .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Andrew Main (Zefram) <zefram@fysh.org> .PP The original Eksblowfish code (in the form of \fBcrypt()\fR) from which this module is derived is in the public domain. It may be found at <http://www.openwall.com/crypt/>. .SH "LICENSE" .IX Header "LICENSE" This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.