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lib/Digest/MD5.pm  view on Meta::CPAN

package Digest::MD5;

use strict;
use warnings;

use Exporter;
use XSLoader;

our $VERSION = 0.06;
our @EXPORT_OK = qw(md5 md5_hex md5_base64);

*import = \&Exporter::import;

our @ISA;
eval {
	require Digest::base;
	@ISA = qw/Digest::base/;
};
if ($@) {
	my $err = $@;
	*add_bits = sub { die $err };
}

XSLoader::load('Digest::MD5', $VERSION);
*reset = \&new;

1;

=encoding utf8

=head1 NAME

Digest::MD5 - Perl interface to the MD5 Algorithm

=head1 SYNOPSIS

 # Functional style
 use Digest::MD5 qw(md5 md5_hex md5_base64);

 $digest = md5($data);
 $digest = md5_hex($data);
 $digest = md5_base64($data);

 # OO style
 use Digest::MD5;

 $ctx = Digest::MD5->new;

 $ctx->add($data);
 $ctx->addfile($file_handle);

 $digest = $ctx->digest;
 $digest = $ctx->hexdigest;
 $digest = $ctx->b64digest;

=head1 DESCRIPTION

The C<Digest::MD5> module allows you to use the RSA Data Security
Inc. MD5 Message Digest algorithm from within Perl programs.  The
algorithm takes as input a message of arbitrary length and produces as
output a 128-bit "fingerprint" or "message digest" of the input.

Note that the MD5 algorithm is not as strong as it used to be.  It has
since 2005 been easy to generate different messages that produce the
same MD5 digest.  It still seems hard to generate messages that
produce a given digest, but it is probably wise to move to stronger
algorithms for applications that depend on the digest to uniquely identify
a message.

The C<Digest::MD5> module provide a procedural interface for simple
use, as well as an object oriented interface that can handle messages
of arbitrary length and which can read files directly.

=head1 FUNCTIONS

The following functions are provided by the C<Digest::MD5> module.
None of these functions are exported by default.

=over 4

=item md5($data,...)

This function will concatenate all arguments, calculate the MD5 digest
of this "message", and return it in binary form.  The returned string
will be 16 bytes long.

The result of md5("a", "b", "c") will be exactly the same as the
result of md5("abc").

lib/Digest/MD5.pm  view on Meta::CPAN

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

The above example would print out the message:

    Digest is 6df23dc03f9b54cc38a0fc1483df6e21

The same checksum can also be calculated in OO style:

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

With OO style, you can break the message arbitrarily.  This means that we
are no longer limited to have space for the whole message in memory, i.e.
we can handle messages of any size.

This is useful when calculating checksum for files:

    use Digest::MD5;

    my $filename = shift || "/etc/passwd";
    open (my $fh, '<', $filename) or die "Can't open '$filename': $!";
    binmode($fh);

    my $md5 = Digest::MD5->new;
    while (<$fh>) {
        $md5->add($_);
    }
    close($fh);
    print $md5->b64digest, " $filename\n";

Or we can use the addfile method for more efficient reading of
the file:

    use Digest::MD5;

    my $filename = shift || "/etc/passwd";
    open (my $fh, '<', $filename) or die "Can't open '$filename': $!";
    binmode ($fh);

    print Digest::MD5->new->addfile($fh)->hexdigest, " $filename\n";

Since the MD5 algorithm is only defined for strings of bytes, it can not be
used on strings that contains chars with ordinal number above 255 (Unicode
strings).  The MD5 functions and methods will croak if you try to feed them
such input data:

    use Digest::MD5 qw(md5_hex);

    my $str = "abc\x{300}";
    print md5_hex($str), "\n";  # croaks
    # Wide character in subroutine entry

What you can do is calculate the MD5 checksum of the UTF-8
representation of such strings.  This is achieved by filtering the
string through encode_utf8() function:

    use Digest::MD5 qw(md5_hex);
    use Encode qw(encode_utf8);

    my $str = "abc\x{300}";
    print md5_hex(encode_utf8($str)), "\n";
    # 8c2d46911f3f5a326455f0ed7a8ed3b3

=head1 SEE ALSO

L<Digest>,
L<Digest::MD2>,
L<Digest::SHA>,
L<Digest::HMAC>

L<md5sum(1)>

RFC 1321

http://en.wikipedia.org/wiki/MD5

The paper "How to Break MD5 and Other Hash Functions" by Xiaoyun Wang
and Hongbo Yu.

=head1 COPYRIGHT

This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.

 Copyright 2023-2026 Michal Josef Špaček.
 Copyright 1998-2003 Gisle Aas.
 Copyright 1995-1996 Neil Winton.
 Copyright 1991-1992 RSA Data Security, Inc.

The MD5 algorithm is defined in RFC 1321. This implementation is
derived from the reference C code in RFC 1321 which is covered by
the following copyright statement:

=over 4

=item

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.

=back

This copyright does not prohibit distribution of any version of Perl