1package Digest::MD5; 2 3use strict; 4use vars qw($VERSION @ISA @EXPORT_OK); 5 6$VERSION = '2.55'; 7 8require Exporter; 9*import = \&Exporter::import; 10@EXPORT_OK = qw(md5 md5_hex md5_base64); 11 12eval { 13 require Digest::base; 14 push(@ISA, 'Digest::base'); 15}; 16if ($@) { 17 my $err = $@; 18 *add_bits = sub { die $err }; 19} 20 21 22eval { 23 require XSLoader; 24 XSLoader::load('Digest::MD5', $VERSION); 25}; 26if ($@) { 27 my $olderr = $@; 28 eval { 29 # Try to load the pure perl version 30 require Digest::Perl::MD5; 31 32 Digest::Perl::MD5->import(qw(md5 md5_hex md5_base64)); 33 unshift(@ISA, "Digest::Perl::MD5"); # make OO interface work 34 }; 35 if ($@) { 36 # restore the original error 37 die $olderr; 38 } 39} 40else { 41 *reset = \&new; 42} 43 441; 45__END__ 46 47=head1 NAME 48 49Digest::MD5 - Perl interface to the MD5 Algorithm 50 51=head1 SYNOPSIS 52 53 # Functional style 54 use Digest::MD5 qw(md5 md5_hex md5_base64); 55 56 $digest = md5($data); 57 $digest = md5_hex($data); 58 $digest = md5_base64($data); 59 60 # OO style 61 use Digest::MD5; 62 63 $ctx = Digest::MD5->new; 64 65 $ctx->add($data); 66 $ctx->addfile($file_handle); 67 68 $digest = $ctx->digest; 69 $digest = $ctx->hexdigest; 70 $digest = $ctx->b64digest; 71 72=head1 DESCRIPTION 73 74The C<Digest::MD5> module allows you to use the RSA Data Security 75Inc. MD5 Message Digest algorithm from within Perl programs. The 76algorithm takes as input a message of arbitrary length and produces as 77output a 128-bit "fingerprint" or "message digest" of the input. 78 79Note that the MD5 algorithm is not as strong as it used to be. It has 80since 2005 been easy to generate different messages that produce the 81same MD5 digest. It still seems hard to generate messages that 82produce a given digest, but it is probably wise to move to stronger 83algorithms for applications that depend on the digest to uniquely identify 84a message. 85 86The C<Digest::MD5> module provide a procedural interface for simple 87use, as well as an object oriented interface that can handle messages 88of arbitrary length and which can read files directly. 89 90=head1 FUNCTIONS 91 92The following functions are provided by the C<Digest::MD5> module. 93None of these functions are exported by default. 94 95=over 4 96 97=item md5($data,...) 98 99This function will concatenate all arguments, calculate the MD5 digest 100of this "message", and return it in binary form. The returned string 101will be 16 bytes long. 102 103The result of md5("a", "b", "c") will be exactly the same as the 104result of md5("abc"). 105 106=item md5_hex($data,...) 107 108Same as md5(), but will return the digest in hexadecimal form. The 109length of the returned string will be 32 and it will only contain 110characters from this set: '0'..'9' and 'a'..'f'. 111 112=item md5_base64($data,...) 113 114Same as md5(), but will return the digest as a base64 encoded string. 115The length of the returned string will be 22 and it will only contain 116characters from this set: 'A'..'Z', 'a'..'z', '0'..'9', '+' and 117'/'. 118 119Note that the base64 encoded string returned is not padded to be a 120multiple of 4 bytes long. If you want interoperability with other 121base64 encoded md5 digests you might want to append the redundant 122string "==" to the result. 123 124=back 125 126=head1 METHODS 127 128The object oriented interface to C<Digest::MD5> is described in this 129section. After a C<Digest::MD5> object has been created, you will add 130data to it and finally ask for the digest in a suitable format. A 131single object can be used to calculate multiple digests. 132 133The following methods are provided: 134 135=over 4 136 137=item $md5 = Digest::MD5->new 138 139The constructor returns a new C<Digest::MD5> object which encapsulate 140the state of the MD5 message-digest algorithm. 141 142If called as an instance method (i.e. $md5->new) it will just reset the 143state the object to the state of a newly created object. No new 144object is created in this case. 145 146=item $md5->reset 147 148This is just an alias for $md5->new. 149 150=item $md5->clone 151 152This a copy of the $md5 object. It is useful when you do not want to 153destroy the digests state, but need an intermediate value of the 154digest, e.g. when calculating digests iteratively on a continuous data 155stream. Example: 156 157 my $md5 = Digest::MD5->new; 158 while (<>) { 159 $md5->add($_); 160 print "Line $.: ", $md5->clone->hexdigest, "\n"; 161 } 162 163=item $md5->add($data,...) 164 165The $data provided as argument are appended to the message we 166calculate the digest for. The return value is the $md5 object itself. 167 168All these lines will have the same effect on the state of the $md5 169object: 170 171 $md5->add("a"); $md5->add("b"); $md5->add("c"); 172 $md5->add("a")->add("b")->add("c"); 173 $md5->add("a", "b", "c"); 174 $md5->add("abc"); 175 176=item $md5->addfile($io_handle) 177 178The $io_handle will be read until EOF and its content appended to the 179message we calculate the digest for. The return value is the $md5 180object itself. 181 182The addfile() method will croak() if it fails reading data for some 183reason. If it croaks it is unpredictable what the state of the $md5 184object will be in. The addfile() method might have been able to read 185the file partially before it failed. It is probably wise to discard 186or reset the $md5 object if this occurs. 187 188In most cases you want to make sure that the $io_handle is in 189C<binmode> before you pass it as argument to the addfile() method. 190 191=item $md5->add_bits($data, $nbits) 192 193=item $md5->add_bits($bitstring) 194 195Since the MD5 algorithm is byte oriented you might only add bits as 196multiples of 8, so you probably want to just use add() instead. The 197add_bits() method is provided for compatibility with other digest 198implementations. See L<Digest> for description of the arguments 199that add_bits() take. 200 201=item $md5->digest 202 203Return the binary digest for the message. The returned string will be 20416 bytes long. 205 206Note that the C<digest> operation is effectively a destructive, 207read-once operation. Once it has been performed, the C<Digest::MD5> 208object is automatically C<reset> and can be used to calculate another 209digest value. Call $md5->clone->digest if you want to calculate the 210digest without resetting the digest state. 211 212=item $md5->hexdigest 213 214Same as $md5->digest, but will return the digest in hexadecimal 215form. The length of the returned string will be 32 and it will only 216contain characters from this set: '0'..'9' and 'a'..'f'. 217 218=item $md5->b64digest 219 220Same as $md5->digest, but will return the digest as a base64 encoded 221string. The length of the returned string will be 22 and it will only 222contain characters from this set: 'A'..'Z', 'a'..'z', '0'..'9', '+' 223and '/'. 224 225 226The base64 encoded string returned is not padded to be a multiple of 4 227bytes long. If you want interoperability with other base64 encoded 228md5 digests you might want to append the string "==" to the result. 229 230=item @ctx = $md5->context 231 232=item $md5->context(@ctx) 233 234Saves or restores the internal state. When called with no arguments, 235returns a 3-element list: number of blocks processed, a 16-byte 236internal state buffer, then up to 63 bytes of unprocessed data. When 237passed those same arguments, restores the state. This is only useful 238for specialised operations. 239 240=back 241 242 243=head1 EXAMPLES 244 245The simplest way to use this library is to import the md5_hex() 246function (or one of its cousins): 247 248 use Digest::MD5 qw(md5_hex); 249 print "Digest is ", md5_hex("foobarbaz"), "\n"; 250 251The above example would print out the message: 252 253 Digest is 6df23dc03f9b54cc38a0fc1483df6e21 254 255The same checksum can also be calculated in OO style: 256 257 use Digest::MD5; 258 259 $md5 = Digest::MD5->new; 260 $md5->add('foo', 'bar'); 261 $md5->add('baz'); 262 $digest = $md5->hexdigest; 263 264 print "Digest is $digest\n"; 265 266With OO style, you can break the message arbitrarily. This means that we 267are no longer limited to have space for the whole message in memory, i.e. 268we can handle messages of any size. 269 270This is useful when calculating checksum for files: 271 272 use Digest::MD5; 273 274 my $filename = shift || "/etc/passwd"; 275 open (my $fh, '<', $filename) or die "Can't open '$filename': $!"; 276 binmode($fh); 277 278 $md5 = Digest::MD5->new; 279 while (<$fh>) { 280 $md5->add($_); 281 } 282 close($fh); 283 print $md5->b64digest, " $filename\n"; 284 285Or we can use the addfile method for more efficient reading of 286the file: 287 288 use Digest::MD5; 289 290 my $filename = shift || "/etc/passwd"; 291 open (my $fh, '<', $filename) or die "Can't open '$filename': $!"; 292 binmode ($fh); 293 294 print Digest::MD5->new->addfile($fh)->hexdigest, " $filename\n"; 295 296Since the MD5 algorithm is only defined for strings of bytes, it can not be 297used on strings that contains chars with ordinal number above 255 (Unicode 298strings). The MD5 functions and methods will croak if you try to feed them 299such input data: 300 301 use Digest::MD5 qw(md5_hex); 302 303 my $str = "abc\x{300}"; 304 print md5_hex($str), "\n"; # croaks 305 # Wide character in subroutine entry 306 307What you can do is calculate the MD5 checksum of the UTF-8 308representation of such strings. This is achieved by filtering the 309string through encode_utf8() function: 310 311 use Digest::MD5 qw(md5_hex); 312 use Encode qw(encode_utf8); 313 314 my $str = "abc\x{300}"; 315 print md5_hex(encode_utf8($str)), "\n"; 316 # 8c2d46911f3f5a326455f0ed7a8ed3b3 317 318=head1 SEE ALSO 319 320L<Digest>, 321L<Digest::MD2>, 322L<Digest::SHA>, 323L<Digest::HMAC> 324 325L<md5sum(1)> 326 327RFC 1321 328 329http://en.wikipedia.org/wiki/MD5 330 331The paper "How to Break MD5 and Other Hash Functions" by Xiaoyun Wang 332and Hongbo Yu. 333 334=head1 COPYRIGHT 335 336This library is free software; you can redistribute it and/or 337modify it under the same terms as Perl itself. 338 339 Copyright 1998-2003 Gisle Aas. 340 Copyright 1995-1996 Neil Winton. 341 Copyright 1991-1992 RSA Data Security, Inc. 342 343The MD5 algorithm is defined in RFC 1321. This implementation is 344derived from the reference C code in RFC 1321 which is covered by 345the following copyright statement: 346 347=over 4 348 349=item 350 351Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All 352rights reserved. 353 354License to copy and use this software is granted provided that it 355is identified as the "RSA Data Security, Inc. MD5 Message-Digest 356Algorithm" in all material mentioning or referencing this software 357or this function. 358 359License is also granted to make and use derivative works provided 360that such works are identified as "derived from the RSA Data 361Security, Inc. MD5 Message-Digest Algorithm" in all material 362mentioning or referencing the derived work. 363 364RSA Data Security, Inc. makes no representations concerning either 365the merchantability of this software or the suitability of this 366software for any particular purpose. It is provided "as is" 367without express or implied warranty of any kind. 368 369These notices must be retained in any copies of any part of this 370documentation and/or software. 371 372=back 373 374This copyright does not prohibit distribution of any version of Perl 375containing this extension under the terms of the GNU or Artistic 376licenses. 377 378=head1 AUTHORS 379 380The original C<MD5> interface was written by Neil Winton 381(C<N.Winton@axion.bt.co.uk>). 382 383The C<Digest::MD5> module is written by Gisle Aas <gisle@ActiveState.com>. 384 385=cut 386