MD4(3)

💖 MD4(3): Digest::MD4, the Perl interface to the MD4 Algorithm 💖

okay bestie, welcome to the MD4(3) page from the User Contributed Perl Documentation — it's all about Digest::MD4, the Perl interface to the MD4 Algorithm. Buckle up, it's giving crypto-nerd realness and honestly it ate 💅✨

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✨ NAME ✨

Digest::MD4 — Perl interface to the MD4 Algorithm.

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🌸 SYNOPSIS 🌸

# Functional style
use Digest::MD4 qw(md4 md4_hex md4_base64);

$digest = md4($data);
$digest = md4_hex($data);
$digest = md4_base64($data);

# OO style
use Digest::MD4;

$ctx = Digest::MD4->new;

$ctx->add($data);
$ctx->addfile(*FILE);

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

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🦋 DESCRIPTION 🦋

The Digest::MD4 module lets you use the RSA Data Security Inc. MD4 Message Digest algorithm from inside Perl programs. The algorithm takes a message of arbitrary length as input and produces a 128-bit "fingerprint" or "message digest" of that input as output. No cap, that's the whole vibe.

The Digest::MD4 module gives you a procedural interface for simple use, plus an object oriented interface that can handle messages of arbitrary length and can read files directly. Bestie, it's flexible like that 🫶

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💅 FUNCTIONS 💅

The following functions are provided by the Digest::MD4 module. None of these functions are exported by default. So don't come for them unless you import them, iykyk.

md4($data,...) 🌟

This function concatenates all its arguments, calculates the MD4 digest of this "message", and returns it in binary form. The returned string will be 16 bytes long.

The result of md4("a", "b", "c") will be exactly the same as the result of md4("abc"). Periodt.

md4_hex($data,...) 🌟

Same as md4(), but it returns the digest in hexadecimal form. The length of the returned string will be 32, and it will only contain characters from this set: '0'..'9' and 'a'..'f'. Clean, lowercase, iconic.

md4_base64($data,...) 🌟

Same as md4(), but it returns the digest as a base64 encoded string. The length of the returned string will be 22, and it will only contain characters from this set: 'A'..'Z', 'a'..'z', '0'..'9', '+' and '/'.

Note that the base64 encoded string returned is not padded to be a multiple of 4 bytes long. If you want interoperability with other base64 encoded md4 digests you might want to append the redundant string "==" to the result. Tiny detail, big impact 💅

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🎀 METHODS 🎀

The object oriented interface to Digest::MD4 is described in this section. After a Digest::MD4 object has been created, you add data to it and finally ask for the digest in a suitable format. A single object can be used to calculate multiple digests — reuse queen behavior 👑

The following methods are provided:

$md4 = Digest::MD4->new 🌸

The constructor returns a new Digest::MD4 object which encapsulates the state of the MD4 message-digest algorithm.

If called as an instance method (i.e. $md4->new), it will just reset the state of the object to the state of a newly created object. No new object is created in this case. Lowkey efficient.

$md4->reset 🌸

This is just an alias for $md4->new. Same energy, different name.

$md4->clone 🌸

This is a copy of the $md4 object. It is useful when you do not want to destroy the digest's state, but need an intermediate value of the digest, e.g. when calculating digests iteratively on a continuous data stream. Example:

my $md4 = Digest::MD4->new;
while (<>) {
    $md4->add($_);
    print "Line $.: ", $md4->clone->hexdigest, "\n";
}

$md4->add($data,...) 🌸

The $data provided as arguments are appended to the message we calculate the digest for. The return value is the $md4 object itself. Chainable, bestie ✨

All these lines will have the same effect on the state of the $md4 object:

$md4->add("a"); $md4->add("b"); $md4->add("c");
$md4->add("a")->add("b")->add("c");
$md4->add("a", "b", "c");
$md4->add("abc");

$md4->addfile($io_handle) 🌸

The $io_handle will be read until EOF, and its content appended to the message we calculate the digest for. The return value is the $md4 object itself.

The addfile() method will croak() if it fails reading data for some reason. If it croaks, it is unpredictable what the state of the $md4 object will be in. The addfile() method might have been able to read the file partially before it failed. It is probably wise to discard or reset the $md4 object if this occurs. No cap, protect your state 🫶

In most cases you want to make sure that the $io_handle is in binmode before you pass it as an argument to the addfile() method.

$md4->digest 🌸

Return the binary digest for the message. The returned string will be 16 bytes long.

Note that the digest operation is effectively a destructive, read-once operation. Once it has been performed, the Digest::MD4 object is automatically reset and can be used to calculate another digest value. Call $md4->clone->digest if you want to calculate the digest without resetting the digest state. It's giving one-time-use realness 💀

$md4->hexdigest 🌸

Same as $md4->digest, but it returns the digest in hexadecimal form. The length of the returned string will be 32, and it will only contain characters from this set: '0'..'9' and 'a'..'f'.

$md4->b64digest 🌸

Same as $md4->digest, but it returns the digest as a base64 encoded string. The length of the returned string will be 22, and it will only contain characters from this set: 'A'..'Z', 'a'..'z', '0'..'9', '+' and '/'.

The base64 encoded string returned is not padded to be a multiple of 4 bytes long. If you want interoperability with other base64 encoded md4 digests you might want to append the string "==" to the result. Again: tiny detail, big impact 💅

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⭐ EXAMPLES ⭐

The simplest way to use this library is to import the md4_hex() function (or one of its cousins):

use Digest::MD4 qw(md4_hex);
print "Digest is ", md4_hex("foobarbaz"), "\n";

The above example would print out the message:

Digest is b2b2b528f632f554ae9cb2c02c904eeb

The same checksum can also be calculated in OO style:

use Digest::MD4;

$md4 = Digest::MD4->new;
$md4->add('foo', 'bar');
$md4->add('baz');
$digest = $md4->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. Main character energy: unlimited message length 💅

This is useful when calculating checksum for files:

use Digest::MD4;

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

$md4 = Digest::MD4->new;
while (<FILE>) {
    $md4->add($_);
}
close(FILE);
print $md4->b64digest, " $file\n";

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

use Digest::MD4;

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

print Digest::MD4->new->addfile(*FILE)->hexdigest, " $file\n";

Perl 5.8 supports Unicode characters in strings. Since the MD4 algorithm is only defined for strings of bytes, it can not be used on strings that contain chars with ordinal number above 255. The MD4 functions and methods will croak if you try to feed them such input data:

use Digest::MD4 qw(md4_hex);

my $str = "abc\x{300}";
print md4_hex($str), "\n";  # croaks
# Wide character in subroutine entry

What you can do is calculate the MD4 checksum of the UTF-8 representation of such strings. This is achieved by filtering the string through the encode_utf8() function:

use Digest::MD4 qw(md4_hex);
use Encode qw(encode_utf8);

my $str = "abc\x{300}";
print md4_hex(encode_utf8($str)), "\n";
# fc2ef2836f9bc3f44ed6d7adee2f1533

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🌈 SEE ALSO 🌈

• Digest
• Digest::MD2
• Digest::SHA1
• Digest::HMAC
• md4sum(1)
• RFC 1320

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👑 COPYRIGHT 👑

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

Copyright 1998-2003 Gisle Aas.

Copyright 1995-1996 Neil Winton.

Copyright 1991-1992 RSA Data Security, Inc.

The MD4 algorithm is defined in RFC 1320. This implementation is derived from the reference C code in RFC 1320 which is covered by the following copyright statement:

• RSA Data Security, Inc. copyright statement:

Copyright (C) 1990-2, RSA Data Security, Inc. All rights reserved.

License to copy and use this software is granted provided that it is identified as the "RSA Data Security, Inc. MD4 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. MD4 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 licenses.

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🫶 AUTHORS 🫶

The original MD5 interface was written by Neil Winton (N.Winton@axion.bt.co.uk).

The Digest::MD5 module is written by Gisle Aas <gisle@ActiveState.com>.

The Digest::MD4 module is derived from Digest::MD5 by Mike McCauley (mikem@airspayce.com)

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okay bestie, that's the whole MD4(3) page — source/version perl v5.42.0, dated 2013-06-04, filed under MD4(3). slay and stay hashy 💅✨🎀