MD5(3) User Contributed Perl Documentation MD5(3)
NAME
Digest::MD5 - Perl interface to the MD5 Algorithm
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);
$digest = $ctx->digest;
$digest = $ctx->hexdigest;
$digest = $ctx->b64digest;
DESCRIPTION
The Digest::MD5 module allows you to use the RSA Data
Security Inc. MD5 Message Digest algorithm from within
Perl programs. The algorithm takes as input a message of
arbitrary length and produces as output a 128-bit
"fingerprint" or "message digest" of the input.
The Digest::MD5 module provide a procedural interface for
simple use, as well as an object oriented interface that
can handle messages of arbitrary length and which can read
files directly.
A binary digest will be 16 bytes long. A hex digest will
be 32 characters long. A base64 digest will be 22
characters long.
FUNCTIONS
The following functions can be exported from the
Digest::MD5 module. No functions are exported by default.
md5($data,...)
This function will concatenate all arguments,
calculate the MD5 digest of this "message", and return
it in binary form.
md5_hex($data,...)
Same as md5(), but will return the digest in
hexadecimal form.
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md5_base64($data,...)
Same as md5(), but will return the digest as a base64
encoded string.
The base64 encoded string returned is not padded to be
a multiple of 4 bytes long. If you want
interoperability with other base64 encoded md5 digests
you might want to append the string "==" to the
result.
METHODS
The following methods are available:
$md5 = Digest::MD5->new
The constructor returns a new Digest::MD5 object which
encapsulate the state of the MD5 message-digest
algorithm. You can add data to the object and finally
ask for the digest.
If called as an instance method (i.e. $md5->new) it
will just reset the state the object to the state of a
newly created object. No new object is created in
this case.
$md5->reset
This is just an alias for $md5->new.
$md5->add($data,...)
The $data provided as argument are appended to the
message we calculate the digest for. The return value
is the $md5 object itself.
$md5->addfile($io_handle)
The $io_handle is read until EOF and the content is
appended to the message we calculate the digest for.
The return value is the $md5 object itself.
In most cases you want to make sure that the
$io_handle is set up to be in binmode().
$md5->digest
Return the binary digest for the message.
Note that the digest operation is effectively a
destructive, read-once operation. Once it has been
performed, the Digest::MD5 object is automatically
reset and can be used to calculate another digest
value.
$md5->hexdigest
Same as $md5->digest, but will return the digest in
hexadecimal form.
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$md5->b64digest
Same as $md5->digest, but will return the digest as a
base64 encoded string.
The base64 encoded string returned is not padded to be
a multiple of 4 bytes long. If you want
interoperability with other base64 encoded md5 digests
you might want to append the string "==" to the
result.
EXAMPLES
The simplest way to use this library is to import the
md5_hex() function (or one of its cousins):
use Digest::MD5 qw(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";
With OO style you can break the message arbitrary. 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 $file = shift || "/etc/passwd";
open(FILE, $file) or die "Can't open '$file': $!";
binmode(FILE);
$md5 = Digest::MD5->new;
while (<FILE>) {
$md5->add($_);
}
close(FILE);
print $md5->b64digest, " $file\n";
Or we can use the builtin addfile method for more
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efficient reading of the file:
use Digest::MD5;
my $file = shift || "/etc/passwd";
open(FILE, $file) or die "Can't open '$file': $!";
binmode(FILE);
print Digest::MD5->new->addfile(*FILE)->hexdigest, " $file\n";
SEE ALSO
the Digest manpage, the Digest::MD2 manpage, the
Digest::SHA1 manpage, the Digest::HMAC manpage
the md5sum(1) manpage
RFC 1321
COPYRIGHT
This library is free software; you can redistribute it
and/or modify it under the same terms as Perl itself.
Copyright 1998-2002 Gisle Aas.
Copyright 1995-1996 Neil Winton.
Copyright 1991-1992 RSA Data Security, Inc.
The MD5 algorithm is defined in RFC 1321. 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.
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This copyright does not prohibit distribution of any
version of Perl containing this extension under the terms
of the GNU or Artistic licenses.
AUTHORS
The original MD5 interface was written by Neil Winton
(N.Winton@axion.bt.co.uk).
This release was made by Gisle Aas <gisle@ActiveState.com>
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