Authen::DecHpwd.3pm

Langue: en

Autres versions - même langue

Version: 2008-05-12 (ubuntu - 07/07/09)

Section: 3 (Bibliothèques de fonctions)

NAME

Authen::DecHpwd - DEC VMS password hashing

SYNOPSIS

         use Authen::DecHpwd qw(
                 lgi_hpwd
                 UAI_C_AD_II UAI_C_PURDY UAI_C_PURDY_V UAI_C_PURDY_S
         );
 
         $hash = lgi_hpwd("JRANDOM", "PASSWORD", UAI_C_PURDY_S, 1234);
 
         use Authen::DecHpwd qw(vms_username vms_password);
 
         $username = vms_username($username);
         $password = vms_password($password);
 
 

DESCRIPTION

This module implements the LGI$HPWD password hashing function from VMS, and some associated VMS username and password handling functions.

FUNCTIONS

lgi_hpwd(USERNAME, PASSWORD, ALGORITHM, SALT)
This is the LGI$HPWD function from VMS (but with the parameters in a different order). It hashes the PASSWORD string in a manner determined by the other parameters, and returns the hash as a string of bytes.

ALGORITHM determines which hashing algorithm will be used. It must be the value of one of the algorithm constants supplied by this module (see below). The AUTODIN-II CRC algorithm is currently unimplemented.

SALT must be an integer in the range [0, 2^16). It modifies the hashing so that the same password does not always produce the same hash.

USERNAME is a string that is used as more salt. In VMS it is the username of the account to which the password controls access.

VMS usernames and passwords are constrained in character set and length, and are case-insensitive. This function does not enforce these restrictions, nor perform canonicalisation. If restrictions and canonicalisation are desired then they must be applied separately. The functions "vms_username" and "vms_password" described below may be useful.

UAI_C_AD_II
UAI_C_PURDY
UAI_C_PURDY_V
UAI_C_PURDY_S
These constants are used to identify the four password hashing algorithms used by VMS. They are the ``UAI$C_'' constants in VMS.

UAI_C_AD_II refers to an AUTODIN-II 32-bit CRC algorithm. This is unimplemented by this module.

UAI_C_PURDY, UAI_C_PURDY_V, and UAI_C_PURDY_S refer to successive refinements of an algorithm based on Purdy polynomials. All of these algorithms use the salt and username parameters as salt, use the whole password, and return an eight-byte (64-bit) hash. The main part of the algorithm, the Purdy polynomial, is identical in all three. They differ in the pre-hashing, particularly in the treatment of the username parameter.

In UAI_C_PURDY the username is truncated or space-padded to 12 characters before being hashed in. UAI_C_PURDY_V accepts a variable-length username. UAI_C_PURDY_S accepts a variable-length username and also includes the password length in the hash. UAI_C_PURDY_S also does some extra bit rotations when hashing in the username and password strings, in order to avoid aliasing.

vms_username(USERNAME)
Checks whether the USERNAME string matches VMS username syntax, and canonicalises it. VMS username syntax is 1 to 31 characters from case-insensitive alphanumerics, "_``, and ''$". If the string has correct username syntax then the username is returned in canonical form (uppercase). If the string is not a username then "undef" is returned.
vms_password(PASSWORD)
Checks whether the PASSWORD string is an acceptable VMS password, and canonicalises it. VMS password syntax is 1 to 32 characters from case-insensitive alphanumerics, "_``, and ''$". If the string is an acceptable password then the password is returned in canonical form (uppercase). If the string is not an acceptable password then "undef" is returned.

SEE ALSO

VMS::User

AUTHOR

The original C implementation of LGI$HPWD was written by Shawn Clifford. The code has since been developed by Davide Casale, Mario Ambrogetti, Terence Lee, Jean-loup Gailly, Solar Designer, and Andrew Main (Zefram).

Mike McCauley <mikem@open.com.au> created the first version of "Authen::DecHpwd", establishing the Perl interface. This was based on Shawn Clifford's code without the later developments.

Andrew Main (Zefram) <zefram@fysh.org> created a new "Authen::DecHpwd" based on the more developed C code presently used, and added ancillary functions.

Copyright (C) 2002 Jean-loup Gailly <http://gailly.net>

Based in part on code from John the Ripper, Copyright (C) 1996-2002 Solar Designer

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

LICENSE

This module is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.