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1 | package Digest; |
2 | |
3 | use strict; |
4 | use vars qw($VERSION %MMAP $AUTOLOAD); |
5 | |
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6 | $VERSION = "1.16"; |
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7 | |
8 | %MMAP = ( |
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9 | "SHA-1" => [["Digest::SHA", 1], "Digest::SHA1", ["Digest::SHA2", 1]], |
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10 | "SHA-224" => [["Digest::SHA", 224]], |
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11 | "SHA-256" => [["Digest::SHA", 256], ["Digest::SHA2", 256]], |
12 | "SHA-384" => [["Digest::SHA", 384], ["Digest::SHA2", 384]], |
13 | "SHA-512" => [["Digest::SHA", 512], ["Digest::SHA2", 512]], |
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14 | "HMAC-MD5" => "Digest::HMAC_MD5", |
15 | "HMAC-SHA-1" => "Digest::HMAC_SHA1", |
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16 | "CRC-16" => [["Digest::CRC", type => "crc16"]], |
17 | "CRC-32" => [["Digest::CRC", type => "crc32"]], |
18 | "CRC-CCITT" => [["Digest::CRC", type => "crcccitt"]], |
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19 | "RIPEMD-160" => "Crypt::PIPEMD160", |
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20 | ); |
21 | |
22 | sub new |
23 | { |
24 | shift; # class ignored |
25 | my $algorithm = shift; |
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26 | my $impl = $MMAP{$algorithm} || do { |
27 | $algorithm =~ s/\W+//; |
28 | "Digest::$algorithm"; |
29 | }; |
30 | $impl = [$impl] unless ref($impl); |
31 | my $err; |
32 | for (@$impl) { |
33 | my $class = $_; |
34 | my @args; |
35 | ($class, @args) = @$class if ref($class); |
36 | no strict 'refs'; |
37 | unless (exists ${"$class\::"}{"VERSION"}) { |
38 | eval "require $class"; |
39 | if ($@) { |
40 | $err ||= $@; |
41 | next; |
42 | } |
43 | } |
44 | return $class->new(@args, @_); |
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45 | } |
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46 | die $err; |
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47 | } |
48 | |
49 | sub AUTOLOAD |
50 | { |
51 | my $class = shift; |
52 | my $algorithm = substr($AUTOLOAD, rindex($AUTOLOAD, '::')+2); |
53 | $class->new($algorithm, @_); |
54 | } |
55 | |
56 | 1; |
57 | |
58 | __END__ |
59 | |
60 | =head1 NAME |
61 | |
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62 | Digest - Modules that calculate message digests |
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63 | |
64 | =head1 SYNOPSIS |
65 | |
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66 | $md5 = Digest->new("MD5"); |
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67 | $sha1 = Digest->new("SHA-1"); |
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68 | $sha256 = Digest->new("SHA-256"); |
69 | $sha384 = Digest->new("SHA-384"); |
70 | $sha512 = Digest->new("SHA-512"); |
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71 | |
72 | $hmac = Digest->HMAC_MD5($key); |
73 | |
74 | =head1 DESCRIPTION |
75 | |
76 | The C<Digest::> modules calculate digests, also called "fingerprints" |
77 | or "hashes", of some data, called a message. The digest is (usually) |
78 | some small/fixed size string. The actual size of the digest depend of |
79 | the algorithm used. The message is simply a sequence of arbitrary |
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80 | bytes or bits. |
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81 | |
82 | An important property of the digest algorithms is that the digest is |
83 | I<likely> to change if the message change in some way. Another |
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84 | property is that digest functions are one-way functions, that is it |
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85 | should be I<hard> to find a message that correspond to some given |
86 | digest. Algorithms differ in how "likely" and how "hard", as well as |
87 | how efficient they are to compute. |
88 | |
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89 | Note that the properties of the algorithms change over time, as the |
90 | algorithms are analyzed and machines grow faster. If your application |
91 | for instance depends on it being "impossible" to generate the same |
92 | digest for a different message it is wise to make it easy to plug in |
93 | stronger algorithms as the one used grow weaker. Using the interface |
94 | documented here should make it easy to change algorithms later. |
95 | |
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96 | All C<Digest::> modules provide the same programming interface. A |
97 | functional interface for simple use, as well as an object oriented |
98 | interface that can handle messages of arbitrary length and which can |
99 | read files directly. |
100 | |
101 | The digest can be delivered in three formats: |
102 | |
103 | =over 8 |
104 | |
105 | =item I<binary> |
106 | |
107 | This is the most compact form, but it is not well suited for printing |
108 | or embedding in places that can't handle arbitrary data. |
109 | |
110 | =item I<hex> |
111 | |
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112 | A twice as long string of lowercase hexadecimal digits. |
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113 | |
114 | =item I<base64> |
115 | |
116 | A string of portable printable characters. This is the base64 encoded |
117 | representation of the digest with any trailing padding removed. The |
118 | string will be about 30% longer than the binary version. |
119 | L<MIME::Base64> tells you more about this encoding. |
120 | |
121 | =back |
122 | |
123 | |
124 | The functional interface is simply importable functions with the same |
125 | name as the algorithm. The functions take the message as argument and |
126 | return the digest. Example: |
127 | |
128 | use Digest::MD5 qw(md5); |
129 | $digest = md5($message); |
130 | |
131 | There are also versions of the functions with "_hex" or "_base64" |
132 | appended to the name, which returns the digest in the indicated form. |
133 | |
134 | =head1 OO INTERFACE |
135 | |
136 | The following methods are available for all C<Digest::> modules: |
137 | |
138 | =over 4 |
139 | |
140 | =item $ctx = Digest->XXX($arg,...) |
141 | |
142 | =item $ctx = Digest->new(XXX => $arg,...) |
143 | |
144 | =item $ctx = Digest::XXX->new($arg,...) |
145 | |
146 | The constructor returns some object that encapsulate the state of the |
147 | message-digest algorithm. You can add data to the object and finally |
148 | ask for the digest. The "XXX" should of course be replaced by the proper |
149 | name of the digest algorithm you want to use. |
150 | |
151 | The two first forms are simply syntactic sugar which automatically |
152 | load the right module on first use. The second form allow you to use |
153 | algorithm names which contains letters which are not legal perl |
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154 | identifiers, e.g. "SHA-1". If no implementation for the given algorithm |
155 | can be found, then an exception is raised. |
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156 | |
67859229 |
157 | If new() is called as an instance method (i.e. $ctx->new) it will just |
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158 | reset the state the object to the state of a newly created object. No |
159 | new object is created in this case, and the return value is the |
160 | reference to the object (i.e. $ctx). |
161 | |
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162 | =item $other_ctx = $ctx->clone |
163 | |
164 | The clone method creates a copy of the digest state object and returns |
165 | a reference to the copy. |
166 | |
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167 | =item $ctx->reset |
168 | |
169 | This is just an alias for $ctx->new. |
170 | |
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171 | =item $ctx->add( $data ) |
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172 | |
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173 | =item $ctx->add( $chunk1, $chunk2, ... ) |
174 | |
175 | The string value of the $data provided as argument is appended to the |
176 | message we calculate the digest for. The return value is the $ctx |
177 | object itself. |
178 | |
179 | If more arguments are provided then they are all appended to the |
180 | message, thus all these lines will have the same effect on the state |
181 | of the $ctx object: |
182 | |
183 | $ctx->add("a"); $ctx->add("b"); $ctx->add("c"); |
184 | $ctx->add("a")->add("b")->add("c"); |
185 | $ctx->add("a", "b", "c"); |
186 | $ctx->add("abc"); |
187 | |
188 | Most algorithms are only defined for strings of bytes and this method |
189 | might therefore croak if the provided arguments contain chars with |
190 | ordinal number above 255. |
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191 | |
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192 | =item $ctx->addfile( $io_handle ) |
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193 | |
194 | The $io_handle is read until EOF and the content is appended to the |
195 | message we calculate the digest for. The return value is the $ctx |
196 | object itself. |
197 | |
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198 | The addfile() method will croak() if it fails reading data for some |
199 | reason. If it croaks it is unpredictable what the state of the $ctx |
200 | object will be in. The addfile() method might have been able to read |
201 | the file partially before it failed. It is probably wise to discard |
202 | or reset the $ctx object if this occurs. |
203 | |
204 | In most cases you want to make sure that the $io_handle is in |
205 | "binmode" before you pass it as argument to the addfile() method. |
206 | |
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207 | =item $ctx->add_bits( $data, $nbits ) |
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208 | |
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209 | =item $ctx->add_bits( $bitstring ) |
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210 | |
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211 | The add_bits() method is an alternative to add() that allow partial |
212 | bytes to be appended to the message. Most users should just ignore |
213 | this method as partial bytes is very unlikely to be of any practical |
214 | use. |
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215 | |
216 | The two argument form of add_bits() will add the first $nbits bits |
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217 | from $data. For the last potentially partial byte only the high order |
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218 | C<< $nbits % 8 >> bits are used. If $nbits is greater than C<< |
219 | length($data) * 8 >>, then this method would do the same as C<< |
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220 | $ctx->add($data) >>. |
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221 | |
222 | The one argument form of add_bits() takes a $bitstring of "1" and "0" |
223 | chars as argument. It's a shorthand for C<< $ctx->add_bits(pack("B*", |
224 | $bitstring), length($bitstring)) >>. |
225 | |
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226 | The return value is the $ctx object itself. |
227 | |
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228 | This example shows two calls that should have the same effect: |
229 | |
230 | $ctx->add_bits("111100001010"); |
231 | $ctx->add_bits("\xF0\xA0", 12); |
232 | |
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233 | Most digest algorithms are byte based and for these it is not possible |
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234 | to add bits that are not a multiple of 8, and the add_bits() method |
235 | will croak if you try. |
236 | |
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237 | =item $ctx->digest |
238 | |
239 | Return the binary digest for the message. |
240 | |
241 | Note that the C<digest> operation is effectively a destructive, |
242 | read-once operation. Once it has been performed, the $ctx object is |
243 | automatically C<reset> and can be used to calculate another digest |
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244 | value. Call $ctx->clone->digest if you want to calculate the digest |
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245 | without resetting the digest state. |
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246 | |
247 | =item $ctx->hexdigest |
248 | |
249 | Same as $ctx->digest, but will return the digest in hexadecimal form. |
250 | |
251 | =item $ctx->b64digest |
252 | |
253 | Same as $ctx->digest, but will return the digest as a base64 encoded |
254 | string. |
255 | |
256 | =back |
257 | |
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258 | =head1 Digest speed |
259 | |
260 | This table should give some indication on the relative speed of |
261 | different algorithms. It is sorted by throughput based on a benchmark |
262 | done with of some implementations of this API: |
263 | |
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264 | Algorithm Size Implementation MB/s |
265 | |
266 | MD4 128 Digest::MD4 v1.3 165.0 |
267 | MD5 128 Digest::MD5 v2.33 98.8 |
268 | SHA-256 256 Digest::SHA2 v1.1.0 66.7 |
269 | SHA-1 160 Digest::SHA v4.3.1 58.9 |
270 | SHA-1 160 Digest::SHA1 v2.10 48.8 |
271 | SHA-256 256 Digest::SHA v4.3.1 41.3 |
272 | Haval-256 256 Digest::Haval256 v1.0.4 39.8 |
273 | SHA-384 384 Digest::SHA2 v1.1.0 19.6 |
274 | SHA-512 512 Digest::SHA2 v1.1.0 19.3 |
275 | SHA-384 384 Digest::SHA v4.3.1 19.2 |
276 | SHA-512 512 Digest::SHA v4.3.1 19.2 |
277 | Whirlpool 512 Digest::Whirlpool v1.0.2 13.0 |
278 | MD2 128 Digest::MD2 v2.03 9.5 |
279 | |
280 | Adler-32 32 Digest::Adler32 v0.03 1.3 |
281 | CRC-16 16 Digest::CRC v0.05 1.1 |
282 | CRC-32 32 Digest::CRC v0.05 1.1 |
283 | MD5 128 Digest::Perl::MD5 v1.5 1.0 |
284 | CRC-CCITT 16 Digest::CRC v0.05 0.8 |
285 | |
286 | These numbers was achieved Apr 2004 with ActivePerl-5.8.3 running |
287 | under Linux on a P4 2.8 GHz CPU. The last 5 entries differ by being |
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288 | pure perl implementations of the algorithms, which explains why they |
289 | are so slow. |
290 | |
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291 | =head1 SEE ALSO |
292 | |
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293 | L<Digest::Adler32>, L<Digest::CRC>, L<Digest::Haval256>, |
294 | L<Digest::HMAC>, L<Digest::MD2>, L<Digest::MD4>, L<Digest::MD5>, |
295 | L<Digest::SHA>, L<Digest::SHA1>, L<Digest::SHA2>, L<Digest::Whirlpool> |
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296 | |
297 | New digest implementations should consider subclassing from L<Digest::base>. |
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298 | |
299 | L<MIME::Base64> |
300 | |
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301 | http://en.wikipedia.org/wiki/Cryptographic_hash_function |
302 | |
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303 | =head1 AUTHOR |
304 | |
305 | Gisle Aas <gisle@aas.no> |
306 | |
307 | The C<Digest::> interface is based on the interface originally |
308 | developed by Neil Winton for his C<MD5> module. |
309 | |
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310 | This library is free software; you can redistribute it and/or |
311 | modify it under the same terms as Perl itself. |
312 | |
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313 | Copyright 1998-2006 Gisle Aas. |
314 | Copyright 1995,1996 Neil Winton. |
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315 | |
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316 | =cut |