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


        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(

        $ppr = Authen::Passphrase::LANManagerHalf->from_rfc2307(

        $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 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.


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:


The hash, as a string of 8 bytes.


The hash, as a string of 16 hexadecimal digits.


A passphrase that will be accepted.

Either the hash or the passphrase must be given.


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.


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.



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) <>


Copyright (C) 2006, 2007, 2009, 2010, 2012 Andrew Main (Zefram) <>


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