Digest::Perl::MD53pm

Usage

 # Functional style
 use Digest::MD5  qw(md5 md5_hex md5_base64);
 $hash = md5 $data;
 $hash = md5_hex $data;
 $hash = md5_base64 $data;
    
 # OO style
 use Digest::MD5;
 $ctx = Digest::MD5->new;
 $ctx->add($data);
 $ctx->addfile(*FILE);
 $digest = $ctx->digest;
 $digest = $ctx->hexdigest;
 $digest = $ctx->b64digest;

Disclaimer

This is not an interface (like "Digest::MD5") but a Perl implementation of MD5. It is written in perl only and because of this it is slow but it works without C-Code. You should use "Digest::MD5" instead of this module if it is available. This module is only useful for

•

computers where you cannot install "Digest::MD5" (e.g. lack of a C-Compiler)

•

encrypting only small amounts of data (less than one million bytes). I use it to hash passwords.

•

educational purposes

Overview

This modules has the same interface as the much faster "Digest::MD5". So you can easily exchange them, e.g.

        BEGIN {
          eval {
            require Digest::MD5;
            import Digest::MD5 'md5_hex'
          };
          if ($@) { # ups, no Digest::MD5
            require Digest::Perl::MD5;
            import Digest::Perl::MD5 'md5_hex'
          }             
        }

If the "Digest::MD5" module is available it is used and if not you take "Digest::Perl::MD5".

You can also install the Perl part of Digest::MD5 together with Digest::Perl::MD5 and use Digest::MD5 as normal, it falls back to Digest::Perl::MD5 if it cannot load its object files.

For a detailed Documentation see the "Digest::MD5" module.

Examples

The simplest way to use this library is to import the md5_hex() function (or one of its cousins):

    use Digest::Perl::MD5 'md5_hex';
    print 'Digest is ', md5_hex('foobarbaz'), "\n";

The above example would print out the message

    Digest is 6df23dc03f9b54cc38a0fc1483df6e21

provided that the implementation is working correctly. The same checksum can also be calculated in OO style:

    use Digest::MD5;
    
    $md5 = Digest::MD5->new;
    $md5->add('foo', 'bar');
    $md5->add('baz');
    $digest = $md5->hexdigest;
    
    print "Digest is $digest\n";

The digest methods are destructive. That means you can only call them once and the $md5 objects is reset after use. You can make a copy with clone:

        $md5->clone->hexdigest

Limitations

This implementation of the MD5 algorithm has some limitations:

•

It's slow, very slow. I've done my very best but Digest::MD5 is still about 100 times faster. You can only encrypt Data up to one million bytes in an acceptable time. But it's very useful for encrypting small amounts of data like passwords.

•

You can only encrypt up to 2^32 bits = 512 MB on 32bit archs. But You should use "Digest::MD5" for those amounts of data anyway.