MD5(3)

NNAAMMEE
       MD5 - Perl interface to the RSA Data Security Inc. MD5
       Message-Digest Algorithm

SSYYNNOOPPSSIISS
           use MD5;

           $context = new MD5;
           $context->reset();

           $context->add(LIST);
           $context->addfile(HANDLE);

           $digest = $context->digest();
           $string = $context->hexdigest();

           $digest = MD5->hash(SCALAR);
           $string = MD5->hexhash(SCALAR);

DDEESSCCRRIIPPTTIIOONN
       The MMDD55 module allows you to use the RSA Data Security
       Inc. MD5 Message Digest algorithm from within Perl
       programs.

       A new MD5 context object is created with the nneeww
       operation.  Multiple simultaneous digest contexts can be
       maintained, if desired.  The context is updated with the
       aadddd operation which adds the strings contained in the LIST
       parameter. Note, however, that add('foo', 'bar'),
       add('foo') followed by add('bar') and add('foobar') should
       all give the same result.

       The final message digest value is returned by the ddiiggeesstt
       operation as a 16-byte binary string. This operation
       delivers the result of aadddd operations since the last nneeww
       or rreesseett operation. Note that the ddiiggeesstt operation is
       effectively a destructive, read-once operation. Once it
       has been performed, the context must be rreesseett before being
       used to calculate another digest value.

       Several convenience functions are also provided. The
       aaddddffiillee operation takes an open file-handle and reads it
       until end-of file in 1024 byte blocks adding the contents
       to the context. The file-handle can either be specified by
       name or passed as a type-glob reference, as shown in the
       examples below. The hheexxddiiggeesstt operation calls ddiiggeesstt and
       returns the result as a printable string of hexdecimal
       digits. This is exactly the same operation as performed by
       the uunnppaacckk operation in the examples below.

       The hhaasshh operation can act as either a static member
       function (ie you invoke it on the MD5 class as in the
       synopsis above) or as a normal virtual function. In both

       cases it performs the complete MD5 cycle (reset, add,
       digest) on the supplied scalar value. This is convenient
       for handling small quantities of data. When invoked on the
       class a temporary context is created. When invoked through
       an already created context object, this context is used.
       The latter form is slightly more efficient. The hheexxhhaasshh
       operation is analogous to hheexxddiiggeesstt.

EEXXAAMMPPLLEESS
           use MD5;

           $md5 = new MD5;
           $md5->add('foo', 'bar');
           $md5->add('baz');
           $digest = $md5->digest();

           print("Digest is " . unpack("H*", $digest) . "\n");

       The above example would print out the message

           Digest is 6df23dc03f9b54cc38a0fc1483df6e21

       provided that the implementation is working correctly.

       Remembering the Perl motto ("There's more than one way to
       do it"), the following should all give the same result:

           use MD5;
           $md5 = new MD5;

           die "Can't open /etc/passwd ($!)\n" unless open(P, "/etc/passwd");

           seek(P, 0, 0);
           $md5->reset;
           $md5->addfile(P);
           $d = $md5->hexdigest;
           print "addfile (handle name) = $d\n";

           seek(P, 0, 0);
           $md5->reset;
           $md5->addfile(\*P);
           $d = $md5->hexdigest;
           print "addfile (type-glob reference) = $d\n";

           seek(P, 0, 0);
           $md5->reset;
           while (<P>)
           {
               $md5->add($_);
           }
           $d = $md5->hexdigest;
           print "Line at a time = $d\n";

           seek(P, 0, 0);
           $md5->reset;
           $md5->add(<P>);
           $d = $md5->hexdigest;
           print "All lines at once = $d\n";

           seek(P, 0, 0);
           $md5->reset;
           while (read(P, $data, (rand % 128) + 1))
           {
               $md5->add($data);
           }
           $d = $md5->hexdigest;
           print "Random chunks = $d\n";

           seek(P, 0, 0);
           $md5->reset;
           undef $/;
           $data = <P>;
           $d = $md5->hexhash($data);
           print "Single string = $d\n";

           close(P);

NNOOTTEE
       The MD5 extension may be redistributed under the same
       terms as Perl.  The MD5 algorithm is defined in RFC1321.
       The basic C code implementing the algorithm is derived
       from that in the RFC and is covered by the following
       copyright: Copyright (C) 1991-2, RSA Data Security, Inc.
       Created 1991. All rights reserved.

       License to copy and use this software is granted provided
       that it is identified as the "RSA Data Security, Inc. MD5
       Message-Digest Algorithm" in all material mentioning or
       referencing this software or this function.

       License is also granted to make and use derivative works
       provided that such works are identified as "derived from
       the RSA Data Security, Inc. MD5 Message-Digest Algorithm"
       in all material mentioning or referencing the derived
       work.

       RSA Data Security, Inc. makes no representations
       concerning either the merchantability of this software or
       the suitability of this software for any particular
       purpose. It is provided "as is" without express or implied
       warranty of any kind.

       These notices must be retained in any copies of any part
       of this documentation and/or software.

       This copyright does not prohibit distribution of any

       version of Perl containing this extension under the terms
       of the GNU or Artistic licences.

AAUUTTHHOORR
       The MD5 interface was written by Neil Winton
       N.Winton@axion.bt.co.uk.

SSEEEE AALLSSOO
       perl(1).