Commit | Line | Data |
3357b1b1 |
1 | package Digest; |
2 | |
3 | use strict; |
4 | use 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 | |
20 | sub 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 | |
47 | sub AUTOLOAD |
48 | { |
49 | my $class = shift; |
50 | my $algorithm = substr($AUTOLOAD, rindex($AUTOLOAD, '::')+2); |
51 | $class->new($algorithm, @_); |
52 | } |
53 | |
54 | 1; |
55 | |
56 | __END__ |
57 | |
58 | =head1 NAME |
59 | |
e19eb3c1 |
60 | Digest - 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 | |
74 | The C<Digest::> modules calculate digests, also called "fingerprints" |
75 | or "hashes", of some data, called a message. The digest is (usually) |
76 | some small/fixed size string. The actual size of the digest depend of |
77 | the algorithm used. The message is simply a sequence of arbitrary |
b12d758c |
78 | bytes or bits. |
3357b1b1 |
79 | |
80 | An important property of the digest algorithms is that the digest is |
81 | I<likely> to change if the message change in some way. Another |
82 | property is that digest functions are one-way functions, i.e. it |
83 | should be I<hard> to find a message that correspond to some given |
84 | digest. Algorithms differ in how "likely" and how "hard", as well as |
85 | how efficient they are to compute. |
86 | |
87 | All C<Digest::> modules provide the same programming interface. A |
88 | functional interface for simple use, as well as an object oriented |
89 | interface that can handle messages of arbitrary length and which can |
90 | read files directly. |
91 | |
92 | The digest can be delivered in three formats: |
93 | |
94 | =over 8 |
95 | |
96 | =item I<binary> |
97 | |
98 | This is the most compact form, but it is not well suited for printing |
99 | or embedding in places that can't handle arbitrary data. |
100 | |
101 | =item I<hex> |
102 | |
e19eb3c1 |
103 | A twice as long string of lowercase hexadecimal digits. |
3357b1b1 |
104 | |
105 | =item I<base64> |
106 | |
107 | A string of portable printable characters. This is the base64 encoded |
108 | representation of the digest with any trailing padding removed. The |
109 | string will be about 30% longer than the binary version. |
110 | L<MIME::Base64> tells you more about this encoding. |
111 | |
112 | =back |
113 | |
114 | |
115 | The functional interface is simply importable functions with the same |
116 | name as the algorithm. The functions take the message as argument and |
117 | return the digest. Example: |
118 | |
119 | use Digest::MD5 qw(md5); |
120 | $digest = md5($message); |
121 | |
122 | There are also versions of the functions with "_hex" or "_base64" |
123 | appended to the name, which returns the digest in the indicated form. |
124 | |
125 | =head1 OO INTERFACE |
126 | |
127 | The 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 | |
137 | The constructor returns some object that encapsulate the state of the |
138 | message-digest algorithm. You can add data to the object and finally |
139 | ask for the digest. The "XXX" should of course be replaced by the proper |
140 | name of the digest algorithm you want to use. |
141 | |
142 | The two first forms are simply syntactic sugar which automatically |
143 | load the right module on first use. The second form allow you to use |
144 | algorithm names which contains letters which are not legal perl |
897ff129 |
145 | identifiers, e.g. "SHA-1". If no implementation for the given algorithm |
146 | can be found, then an exception is raised. |
3357b1b1 |
147 | |
67859229 |
148 | If new() is called as an instance method (i.e. $ctx->new) it will just |
3357b1b1 |
149 | reset the state the object to the state of a newly created object. No |
150 | new object is created in this case, and the return value is the |
151 | reference to the object (i.e. $ctx). |
152 | |
70ee4409 |
153 | =item $other_ctx = $ctx->clone |
154 | |
155 | The clone method creates a copy of the digest state object and returns |
156 | a reference to the copy. |
157 | |
3357b1b1 |
158 | =item $ctx->reset |
159 | |
160 | This is just an alias for $ctx->new. |
161 | |
e19eb3c1 |
162 | =item $ctx->add( $data, ... ) |
3357b1b1 |
163 | |
164 | The $data provided as argument are appended to the message we |
165 | calculate the digest for. The return value is the $ctx object itself. |
166 | |
e19eb3c1 |
167 | =item $ctx->addfile( $io_handle ) |
3357b1b1 |
168 | |
169 | The $io_handle is read until EOF and the content is appended to the |
170 | message we calculate the digest for. The return value is the $ctx |
171 | object itself. |
172 | |
e19eb3c1 |
173 | =item $ctx->add_bits( $data, $nbits ) |
b12d758c |
174 | |
e19eb3c1 |
175 | =item $ctx->add_bits( $bitstring ) |
b12d758c |
176 | |
177 | The bits provided are appended to the message we calculate the digest |
178 | for. The return value is the $ctx object itself. |
179 | |
180 | The two argument form of add_bits() will add the first $nbits bits |
181 | from data. For the last potentially partial byte only the high order |
182 | C<< $nbits % 8 >> bits are used. If $nbits is greater than C<< |
183 | length($data) * 8 >>, then this method would do the same as C<< |
184 | $ctx->add($data) >>, i.e. $nbits is silently ignored. |
185 | |
186 | The one argument form of add_bits() takes a $bitstring of "1" and "0" |
187 | chars as argument. It's a shorthand for C<< $ctx->add_bits(pack("B*", |
188 | $bitstring), length($bitstring)) >>. |
189 | |
190 | This example shows two calls that should have the same effect: |
191 | |
192 | $ctx->add_bits("111100001010"); |
193 | $ctx->add_bits("\xF0\xA0", 12); |
194 | |
195 | Most digest algorithms are byte based. For those it is not possible |
196 | to add bits that are not a multiple of 8, and the add_bits() method |
197 | will croak if you try. |
198 | |
3357b1b1 |
199 | =item $ctx->digest |
200 | |
201 | Return the binary digest for the message. |
202 | |
203 | Note that the C<digest> operation is effectively a destructive, |
204 | read-once operation. Once it has been performed, the $ctx object is |
205 | automatically C<reset> and can be used to calculate another digest |
70ee4409 |
206 | value. Call $ctx->clone->digest if you want to calculate the digest |
207 | without reseting the digest state. |
3357b1b1 |
208 | |
209 | =item $ctx->hexdigest |
210 | |
211 | Same as $ctx->digest, but will return the digest in hexadecimal form. |
212 | |
213 | =item $ctx->b64digest |
214 | |
215 | Same as $ctx->digest, but will return the digest as a base64 encoded |
216 | string. |
217 | |
218 | =back |
219 | |
e19eb3c1 |
220 | =head1 Digest speed |
221 | |
222 | This table should give some indication on the relative speed of |
223 | different algorithms. It is sorted by throughput based on a benchmark |
224 | done 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 | |
248 | These numbers was achieved Apr 2004 with ActivePerl-5.8.3 running |
249 | under Linux on a P4 2.8 GHz CPU. The last 5 entries differ by being |
e19eb3c1 |
250 | pure perl implementations of the algorithms, which explains why they |
251 | are so slow. |
252 | |
3357b1b1 |
253 | =head1 SEE ALSO |
254 | |
371dcd31 |
255 | L<Digest::Adler32>, L<Digest::CRC>, L<Digest::Haval256>, |
256 | L<Digest::HMAC>, L<Digest::MD2>, L<Digest::MD4>, L<Digest::MD5>, |
257 | L<Digest::SHA>, L<Digest::SHA1>, L<Digest::SHA2>, L<Digest::Whirlpool> |
e19eb3c1 |
258 | |
259 | New digest implementations should consider subclassing from L<Digest::base>. |
3357b1b1 |
260 | |
261 | L<MIME::Base64> |
262 | |
263 | =head1 AUTHOR |
264 | |
265 | Gisle Aas <gisle@aas.no> |
266 | |
267 | The C<Digest::> interface is based on the interface originally |
268 | developed by Neil Winton for his C<MD5> module. |
269 | |
e19eb3c1 |
270 | This library is free software; you can redistribute it and/or |
271 | modify 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 |