extra code in pp_concat, Take 2
[p5sagit/p5-mst-13.2.git] / lib / Digest.pm
CommitLineData
3357b1b1 1package Digest;
2
3use strict;
4use vars qw($VERSION %MMAP $AUTOLOAD);
5
a9acc356 6$VERSION = "1.10";
3357b1b1 7
8%MMAP = (
b12d758c 9 "SHA-1" => ["Digest::SHA1", ["Digest::SHA", 1], ["Digest::SHA2", 1]],
10 "SHA-256" => [["Digest::SHA", 256], ["Digest::SHA2", 256]],
11 "SHA-384" => [["Digest::SHA", 384], ["Digest::SHA2", 384]],
12 "SHA-512" => [["Digest::SHA", 512], ["Digest::SHA2", 512]],
3357b1b1 13 "HMAC-MD5" => "Digest::HMAC_MD5",
14 "HMAC-SHA-1" => "Digest::HMAC_SHA1",
371dcd31 15 "CRC-16" => [["Digest::CRC", type => "crc16"]],
16 "CRC-32" => [["Digest::CRC", type => "crc32"]],
17 "CRC-CCITT" => [["Digest::CRC", type => "crcccitt"]],
3357b1b1 18);
19
20sub new
21{
22 shift; # class ignored
23 my $algorithm = shift;
b12d758c 24 my $impl = $MMAP{$algorithm} || do {
25 $algorithm =~ s/\W+//;
26 "Digest::$algorithm";
27 };
28 $impl = [$impl] unless ref($impl);
29 my $err;
30 for (@$impl) {
31 my $class = $_;
32 my @args;
33 ($class, @args) = @$class if ref($class);
34 no strict 'refs';
35 unless (exists ${"$class\::"}{"VERSION"}) {
36 eval "require $class";
37 if ($@) {
38 $err ||= $@;
39 next;
40 }
41 }
42 return $class->new(@args, @_);
3357b1b1 43 }
b12d758c 44 die $err;
3357b1b1 45}
46
47sub AUTOLOAD
48{
49 my $class = shift;
50 my $algorithm = substr($AUTOLOAD, rindex($AUTOLOAD, '::')+2);
51 $class->new($algorithm, @_);
52}
53
541;
55
56__END__
57
58=head1 NAME
59
e19eb3c1 60Digest - Modules that calculate message digests
3357b1b1 61
62=head1 SYNOPSIS
63
e19eb3c1 64 $md5 = Digest->new("MD5");
3357b1b1 65 $sha1 = Digest->new("SHA-1");
e19eb3c1 66 $sha256 = Digest->new("SHA-256");
67 $sha384 = Digest->new("SHA-384");
68 $sha512 = Digest->new("SHA-512");
3357b1b1 69
70 $hmac = Digest->HMAC_MD5($key);
71
72=head1 DESCRIPTION
73
74The C<Digest::> modules calculate digests, also called "fingerprints"
75or "hashes", of some data, called a message. The digest is (usually)
76some small/fixed size string. The actual size of the digest depend of
77the algorithm used. The message is simply a sequence of arbitrary
b12d758c 78bytes or bits.
3357b1b1 79
80An important property of the digest algorithms is that the digest is
81I<likely> to change if the message change in some way. Another
82property is that digest functions are one-way functions, i.e. it
83should be I<hard> to find a message that correspond to some given
84digest. Algorithms differ in how "likely" and how "hard", as well as
85how efficient they are to compute.
86
87All C<Digest::> modules provide the same programming interface. A
88functional interface for simple use, as well as an object oriented
89interface that can handle messages of arbitrary length and which can
90read files directly.
91
92The digest can be delivered in three formats:
93
94=over 8
95
96=item I<binary>
97
98This is the most compact form, but it is not well suited for printing
99or embedding in places that can't handle arbitrary data.
100
101=item I<hex>
102
e19eb3c1 103A twice as long string of lowercase hexadecimal digits.
3357b1b1 104
105=item I<base64>
106
107A string of portable printable characters. This is the base64 encoded
108representation of the digest with any trailing padding removed. The
109string will be about 30% longer than the binary version.
110L<MIME::Base64> tells you more about this encoding.
111
112=back
113
114
115The functional interface is simply importable functions with the same
116name as the algorithm. The functions take the message as argument and
117return the digest. Example:
118
119 use Digest::MD5 qw(md5);
120 $digest = md5($message);
121
122There are also versions of the functions with "_hex" or "_base64"
123appended to the name, which returns the digest in the indicated form.
124
125=head1 OO INTERFACE
126
127The following methods are available for all C<Digest::> modules:
128
129=over 4
130
131=item $ctx = Digest->XXX($arg,...)
132
133=item $ctx = Digest->new(XXX => $arg,...)
134
135=item $ctx = Digest::XXX->new($arg,...)
136
137The constructor returns some object that encapsulate the state of the
138message-digest algorithm. You can add data to the object and finally
139ask for the digest. The "XXX" should of course be replaced by the proper
140name of the digest algorithm you want to use.
141
142The two first forms are simply syntactic sugar which automatically
143load the right module on first use. The second form allow you to use
144algorithm names which contains letters which are not legal perl
897ff129 145identifiers, e.g. "SHA-1". If no implementation for the given algorithm
146can be found, then an exception is raised.
3357b1b1 147
67859229 148If new() is called as an instance method (i.e. $ctx->new) it will just
3357b1b1 149reset the state the object to the state of a newly created object. No
150new object is created in this case, and the return value is the
151reference to the object (i.e. $ctx).
152
70ee4409 153=item $other_ctx = $ctx->clone
154
155The clone method creates a copy of the digest state object and returns
156a reference to the copy.
157
3357b1b1 158=item $ctx->reset
159
160This is just an alias for $ctx->new.
161
e19eb3c1 162=item $ctx->add( $data, ... )
3357b1b1 163
164The $data provided as argument are appended to the message we
165calculate the digest for. The return value is the $ctx object itself.
166
e19eb3c1 167=item $ctx->addfile( $io_handle )
3357b1b1 168
169The $io_handle is read until EOF and the content is appended to the
170message we calculate the digest for. The return value is the $ctx
171object itself.
172
e19eb3c1 173=item $ctx->add_bits( $data, $nbits )
b12d758c 174
e19eb3c1 175=item $ctx->add_bits( $bitstring )
b12d758c 176
177The bits provided are appended to the message we calculate the digest
178for. The return value is the $ctx object itself.
179
180The two argument form of add_bits() will add the first $nbits bits
181from data. For the last potentially partial byte only the high order
182C<< $nbits % 8 >> bits are used. If $nbits is greater than C<<
183length($data) * 8 >>, then this method would do the same as C<<
184$ctx->add($data) >>, i.e. $nbits is silently ignored.
185
186The one argument form of add_bits() takes a $bitstring of "1" and "0"
187chars as argument. It's a shorthand for C<< $ctx->add_bits(pack("B*",
188$bitstring), length($bitstring)) >>.
189
190This example shows two calls that should have the same effect:
191
192 $ctx->add_bits("111100001010");
193 $ctx->add_bits("\xF0\xA0", 12);
194
195Most digest algorithms are byte based. For those it is not possible
196to add bits that are not a multiple of 8, and the add_bits() method
197will croak if you try.
198
3357b1b1 199=item $ctx->digest
200
201Return the binary digest for the message.
202
203Note that the C<digest> operation is effectively a destructive,
204read-once operation. Once it has been performed, the $ctx object is
205automatically C<reset> and can be used to calculate another digest
70ee4409 206value. Call $ctx->clone->digest if you want to calculate the digest
207without reseting the digest state.
3357b1b1 208
209=item $ctx->hexdigest
210
211Same as $ctx->digest, but will return the digest in hexadecimal form.
212
213=item $ctx->b64digest
214
215Same as $ctx->digest, but will return the digest as a base64 encoded
216string.
217
218=back
219
e19eb3c1 220=head1 Digest speed
221
222This table should give some indication on the relative speed of
223different algorithms. It is sorted by throughput based on a benchmark
224done with of some implementations of this API:
225
371dcd31 226 Algorithm Size Implementation MB/s
227
228 MD4 128 Digest::MD4 v1.3 165.0
229 MD5 128 Digest::MD5 v2.33 98.8
230 SHA-256 256 Digest::SHA2 v1.1.0 66.7
231 SHA-1 160 Digest::SHA v4.3.1 58.9
232 SHA-1 160 Digest::SHA1 v2.10 48.8
233 SHA-256 256 Digest::SHA v4.3.1 41.3
234 Haval-256 256 Digest::Haval256 v1.0.4 39.8
235 SHA-384 384 Digest::SHA2 v1.1.0 19.6
236 SHA-512 512 Digest::SHA2 v1.1.0 19.3
237 SHA-384 384 Digest::SHA v4.3.1 19.2
238 SHA-512 512 Digest::SHA v4.3.1 19.2
239 Whirlpool 512 Digest::Whirlpool v1.0.2 13.0
240 MD2 128 Digest::MD2 v2.03 9.5
241
242 Adler-32 32 Digest::Adler32 v0.03 1.3
243 CRC-16 16 Digest::CRC v0.05 1.1
244 CRC-32 32 Digest::CRC v0.05 1.1
245 MD5 128 Digest::Perl::MD5 v1.5 1.0
246 CRC-CCITT 16 Digest::CRC v0.05 0.8
247
248These numbers was achieved Apr 2004 with ActivePerl-5.8.3 running
249under Linux on a P4 2.8 GHz CPU. The last 5 entries differ by being
e19eb3c1 250pure perl implementations of the algorithms, which explains why they
251are so slow.
252
3357b1b1 253=head1 SEE ALSO
254
371dcd31 255L<Digest::Adler32>, L<Digest::CRC>, L<Digest::Haval256>,
256L<Digest::HMAC>, L<Digest::MD2>, L<Digest::MD4>, L<Digest::MD5>,
257L<Digest::SHA>, L<Digest::SHA1>, L<Digest::SHA2>, L<Digest::Whirlpool>
e19eb3c1 258
259New digest implementations should consider subclassing from L<Digest::base>.
3357b1b1 260
261L<MIME::Base64>
262
263=head1 AUTHOR
264
265Gisle Aas <gisle@aas.no>
266
267The C<Digest::> interface is based on the interface originally
268developed by Neil Winton for his C<MD5> module.
269
e19eb3c1 270This library is free software; you can redistribute it and/or
271modify it under the same terms as Perl itself.
272
897ff129 273 Copyright 1998-2001,2003-2004 Gisle Aas.
e19eb3c1 274 Copyright 1995-1996 Neil Winton.
275
3357b1b1 276=cut