Authen::Passphrase::LANManagerHalf (3pm)

        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;

An object of this class encapsulates half of a passphrase hashed using the Microsoft \s-1LAN\s0 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 \s-1LAN\s0 Manager hash function, see Authen::Passphrase::LANManager.

In a spectacularly bad design decision, the Microsoft \s-1LAN\s0 Manager hash function splits the passphrase into two parts and hashes them separately. It is therefore possible to separate the halves of a \s-1LAN\s0 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 \s-1DES\s0 key, to encrypt the fixed plaintext block \*(L"\s-1KGS\s0!@#$%\*(R". 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.

Authen::Passphrase::LANManagerHalf->new(\s-1ATTR\s0 => \s-1VALUE\s0, ...)

Generates a new passphrase recogniser object using the \s-1LAN\s0 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(\s-1PASSWD\s0)

Generates a new \s-1LAN\s0 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(\s-1USERPASSWORD\s0)

Generates a new \s-1LAN\s0 Manager half passphrase recogniser object from an \s-1RFC\s0 2307 string. The string must consist of "{\s-1CRYPT\s0}" (case insensitive) followed by an acceptable crypt string.

Returns the hash value, as a string of 8 bytes. Returns the hash value, as a string of 16 hexadecimal digits. These methods are part of the standard Authen::Passphrase interface.

Authen::Passphrase, Authen::Passphrase::LANManager, Crypt::DES

Andrew Main (Zefram) <[email protected]>

Copyright (C) 2006, 2007, 2009, 2010, 2012 Andrew Main (Zefram) <[email protected]>

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