Profile of Crypt/Eksblowfish/Subkeyed.pm

Filename	/usr/lib/x86_64-linux-gnu/perl5/5.20/Crypt/Eksblowfish/Subkeyed.pm
Statements	Executed 12 statements in 254µs

Subroutines
Calls	P	F	Exclusive Time	Inclusive Time	Subroutine
1	1	1	16µs	16µs	Crypt::Eksblowfish::Subkeyed::BEGIN@73
1	1	1	15µs	15µs	Crypt::Eksblowfish::Subkeyed::BEGIN@69
1	1	1	9µs	16µs	Crypt::Eksblowfish::Subkeyed::BEGIN@70
1	1	1	6µs	16µs	Crypt::Eksblowfish::Subkeyed::BEGIN@71

Call graph for these subroutines as a Graphviz dot language file.

Line	State ments	Time on line	Calls	Time in subs	Code
1					=head1 NAME
2
3					Crypt::Eksblowfish::Subkeyed - Blowfish/Eksblowfish with access to subkeys
4
5					=head1 SYNOPSIS
6
7					use Crypt::Eksblowfish::Subkeyed;
8
9					$block_size = Crypt::Eksblowfish::Subkeyed->blocksize;
10
11					$cipher = Crypt::Eksblowfish::Subkeyed
12					->new_from_subkeys(\@p_array, \@s_boxes);
13					$cipher = Crypt::Eksblowfish::Subkeyed->new_initial;
14
15					$block_size = $cipher->blocksize;
16					$ciphertext = $cipher->encrypt($plaintext);
17					$plaintext = $cipher->decrypt($ciphertext);
18
19					$p_array = $cipher->p_array;
20					$s_boxes = $cipher->s_boxes;
21					if($cipher->is_weak) { ...
22
23					=head1 DESCRIPTION
24
25					An object of this class encapsulates a keyed instance of the Blowfish
26					or Eksblowfish block cipher, ready to encrypt and decrypt. Normally
27					this class will not be used directly, but through subclasses such as
28					L<Crypt::Eksblowfish>.
29
30					Eksblowfish is a variant of the Blowfish cipher with a modified key setup
31					algorithm. This class doesn't implement either form of key setup, but
32					only provides the actual encryption and decryption parts of the ciphers.
33					This part is shared between Blowfish and Eksblowfish, and also any other
34					cipher that uses the core of Blowfish but supplies its own key setup.
35					This class has "Eksblowfish" in its name rather than "Blowfish" merely
36					due to the historical accident that it is derived from the encryption
37					engine that was used to implement Eksblowfish.
38
39					The key setup phase of a block cipher, also known as the "key
40					schedule", produces a set of "subkeys", which are somewhat like ordinary
41					cryptographic keys (which are the input to the key setup algorithm) but
42					are much larger. In some block ciphers the subkeys also have special
43					interrelationships. In Blowfish the subkeys consist of a "P-array" of 18
44					32-bit entries (one per encryption round plus two more) and four "S-boxes"
45					("S" is for "substitution") each of which consists of 256 32-bit entries.
46					There is no special relationship between the values of the subkeys.
47
48					Methods in this class allow a cipher object to be constructed from
49					a full set of subkeys, and for the subkeys to be extracted from a
50					cipher object. Normal users don't need to do either of these things.
51					It's mainly useful when devising a new key schedule to stick onto the
52					Blowfish core, or when performing cryptanalysis of the cipher algorithm.
53
54					Generating subkeys directly by a strong random process, rather than by
55					expansion of a smaller random key, is an expensive and slightly bizarre
56					way to get greater cryptographic strength from a cipher algorithm.
57					It eliminates attacks on the key schedule, and yields the full strength
58					of the core algorithm. However, this is always a lot less strength than
59					the amount of subkey material, whereas a normal key schedule is designed
60					to yield strength equal to the length of the (much shorter) key. Also,
61					any non-randomness in the source of the subkey material is likely to
62					lead to a cryptographic weakness, whereas a key schedule conceals any
63					non-randomness in the choice of the key.
64
65					=cut
66
67					package Crypt::Eksblowfish::Subkeyed;
68
69	3	43µs	1	15µs	# spent 15µs within Crypt::Eksblowfish::Subkeyed::BEGIN@69 which was called: # once (15µs+0s) by parent::import at line 69 { use 5.006; } # spent 15µs making 1 call to Crypt::Eksblowfish::Subkeyed::BEGIN@69
70	2	21µs	2	22µs	# spent 16µs (9+6) within Crypt::Eksblowfish::Subkeyed::BEGIN@70 which was called: # once (9µs+6µs) by parent::import at line 70 use warnings; # spent 16µs making 1 call to Crypt::Eksblowfish::Subkeyed::BEGIN@70 # spent 6µs making 1 call to warnings::import
71	2	18µs	2	26µs	# spent 16µs (6+10) within Crypt::Eksblowfish::Subkeyed::BEGIN@71 which was called: # once (6µs+10µs) by parent::import at line 71 use strict; # spent 16µs making 1 call to Crypt::Eksblowfish::Subkeyed::BEGIN@71 # spent 10µs making 1 call to strict::import
72
73	2	108µs	1	16µs	# spent 16µs within Crypt::Eksblowfish::Subkeyed::BEGIN@73 which was called: # once (16µs+0s) by parent::import at line 73 use XSLoader; # spent 16µs making 1 call to Crypt::Eksblowfish::Subkeyed::BEGIN@73
74
75	1	500ns			our $VERSION = "0.009";
76
77	1	60µs	1	51µs	XSLoader::load("Crypt::Eksblowfish", $VERSION); # spent 51µs making 1 call to XSLoader::load
78
79					=head1 CLASS METHODS
80
81					=over
82
83					=item Crypt::Eksblowfish::Subkeyed->blocksize
84
85					Returns 8, indicating the Eksblowfish block size of 8 octets. This method
86					may be called on either the class or an instance.
87
88					=back
89
90					=head1 CONSTRUCTOR
91
92					=over
93
94					=item Crypt::Eksblowfish::Subkeyed->new_from_subkeys(ROUND_KEYS, SBOXES)
95
96					Creates a new Blowfish cipher object encapsulating the supplied subkeys.
97					ROUND_KEYS must be a reference to an array of 18 32-bit integers.
98					SBOXES must be a reference to an array of four references to 256-element
99					arrays of 32-bit integers. These subkeys are used in the standard order
100					for Blowfish.
101
102					=item Crypt::Eksblowfish::Subkeyed->new_initial
103
104					The standard Blowfish key schedule is an iterative process, which uses
105					the cipher algorithm to progressively replace subkeys, thus mutating the
106					cipher for subsequent iterations of keying. The Eksblowfish key schedule
107					works similarly, but with a lot more iterations. In both cases, the
108					key setup algorithm begins with a standard set of subkeys, consisting
109					of the initial bits of the fractional part of pi. This constructor
110					creates and returns a Blowfish block cipher object with that standard
111					initial set of subkeys. This is probably useful only to designers of
112					novel key schedules.
113
114					=back
115
116					=head1 METHODS
117
118					=over
119
120					=item $cipher->blocksize
121
122					Returns 8, indicating the Eksblowfish block size of 8 octets. This method
123					may be called on either the class or an instance.
124
125					=item $cipher->encrypt(PLAINTEXT)
126
127					PLAINTEXT must be exactly eight octets. The block is encrypted, and
128					the ciphertext is returned.
129
130					=item $cipher->decrypt(CIPHERTEXT)
131
132					CIPHERTEXT must be exactly eight octets. The block is decrypted, and
133					the plaintext is returned.
134
135					=item $cipher->p_array
136
137					Returns a reference to an 18-element array containing the 32-bit round
138					keys used in this cipher object.
139
140					=item $cipher->s_boxes
141
142					Returns a reference to a 4-element array containing the S-boxes used in
143					this cipher object. Each S-box is a 256-element array of 32-bit entries.
144
145					=item $cipher->is_weak
146
147					Returns a truth value indicating whether this is a weak key. A key is
148					considered weak if any S-box contains a pair of identical entries
149					(in any positions). When Blowfish is used with such an S-box, certain
150					cryptographic attacks are possible that are not possible against most
151					keys. The current (as of 2007) cryptanalytic results on Blowfish do
152					not include an actual break of the algorithm when weak keys are used,
153					but if a break is ever developed then it is likely to be achieved for
154					weak keys before it is achieved for the general case.
155
156					About one key in every 2^15 is weak (if the keys are randomly selected).
157					Because of the complicated key schedule in standard Blowfish it is not
158					possible to predict which keys will be weak without first performing the
159					full key setup, which is why this is a method on the keyed cipher object.
160					In some uses of Blowfish it may be desired to avoid weak keys; if so,
161					check using this method and generate a new random key when a weak key
162					is detected. Bruce Schneier, the designer of Blowfish, says it is
163					probably not worth avoiding weak keys.
164
165					=back
166
167					=head1 SEE ALSO
168
169					L<Crypt::Eksblowfish>,
170					L<Crypt::Eksblowfish::Blowfish>,
171					L<http://www.schneier.com/paper-blowfish-fse.html>
172
173					=head1 AUTHOR
174
175					Eksblowfish guts originally by Solar Designer (solar at openwall.com).
176
177					Modifications and Perl interface by Andrew Main (Zefram)
178					<zefram@fysh.org>.
179
180					=head1 COPYRIGHT
181
182					Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011
183					Andrew Main (Zefram) <zefram@fysh.org>
184
185					The original Eksblowfish code (in the form of crypt()) from which
186					this module is derived is in the public domain. It may be found at
187					L<http://www.openwall.com/crypt/>.
188
189					=head1 LICENSE
190
191					This module is free software; you can redistribute it and/or modify it
192					under the same terms as Perl itself.
193
194					=cut
195
196	1	3µs			1;