---
name: "Authen::Passphrase::LANManagerHalf"
section: "3pm"
platform: "linux"
package: "libauthen-passphrase-perl"
version: "0.008-3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Authen::Passphrase::LANManagerHalf"
---

# Authen::Passphrase::LANManagerHalf(3pm)

passphrases using half the LAN Manager algorithm

## 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.