Authen::Passphrase::LANManagerHalf(3)

NAME
Authen::Passphrase::LANManagerHalf - passphrases using half the LAN Manager algorithm

SYNOPSIS
        use Authen::Passphrase::LANManagerHalf;

        $ppr = Authen::Passphrase::LANManagerHalf->new(
                hash_hex => "855c3697d9979e78");

        $ppr = Authen::Passphrase::LANManagerHalf->new(
                passphrase => "passphr");

        $ppr = Authen::Passphrase::LANManagerHalf->from_crypt(
                '$LM$855c3697d9979e78');

        $ppr = Authen::Passphrase::LANManagerHalf->from_rfc2307(
                '{CRYPT}$LM$855c3697d9979e78');

        $hash = $ppr->hash;
        $hash_hex = $ppr->hash_hex;

        if($ppr->match($passphrase)) { ...

        $passwd = $ppr->as_crypt;
        $userPassword = $ppr->as_rfc2307;

DESCRIPTION
An object of this class encapsulates half of a passphrase hashed using the Microsoft LAN Manager hash function. This is a subclass of Authen::Passphrase, and this document assumes that the reader is familiar with the documentation for that class. For the complete LAN Manager hash function, see Authen::Passphrase::LANManager.

In a spectacularly bad design decision, the Microsoft LAN Manager hash function splits the passphrase into two parts and hashes them separately. It is therefore possible to separate the halves of a LAN Manager hash, and do things with them (such as crack them) separately. This class is about using such a hash half on its own.

The half hash algorithm can be used on up to seven Latin-1 characters of passphrase. First the passphrase is folded to uppercase, and zero-padded to seven bytes. Then the seven bytes are used as a 56-bit DES key, to encrypt the fixed plaintext block "KGS!@#$%". The eight byte ciphertext block is the half hash. There is no salt.

Warning: Don't even think about using this seriously. It's an exceptionally weak design, flawed in pretty much every respect.

CONSTRUCTORS

Authen::Passphrase::LANManagerHalf->new(ATTR => VALUE, ...)
    Generates a new passphrase recogniser object using the LAN Manager half hash algorithm. The following attributes may be given:

    hash
        The hash, as a string of 8 bytes.

    hash_hex
        The hash, as a string of 16 hexadecimal digits.

    passphrase
        A passphrase that will be accepted.

    Either the hash or the passphrase must be given.

Authen::Passphrase::LANManagerHalf->from_crypt(PASSWD)
    Generates a new LAN Manager half passphrase recogniser object from a crypt string. The crypt string must consist of "$LM$" followed by the hash in lowercase hexadecimal.

Authen::Passphrase::LANManagerHalf->from_rfc2307(USERPASSWORD)
    Generates a new LAN Manager half passphrase recogniser object from an RFC 2307 string. The string must consist of "{CRYPT}" (case insensitive) followed by an acceptable crypt string.

METHODS

$ppr->hash
    Returns the hash value, as a string of 8 bytes.

$ppr->hash_hex
    Returns the hash value, as a string of 16 hexadecimal digits.

$ppr->match(PASSPHRASE)
$ppr->as_crypt
$ppr->as_rfc2307
    These methods are part of the standard Authen::Passphrase interface.

SEE ALSO
Authen::Passphrase, Authen::Passphrase::LANManager, Crypt::DES

AUTHOR
Andrew Main (Zefram) <zefram@fysh.org>

COPYRIGHT
Copyright (C) 2006, 2007, 2009, 2010, 2012 Andrew Main (Zefram) <zefram@fysh.org>

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