1Authen::DecHpwd(3) User Contributed Perl Documentation Authen::DecHpwd(3)
2
6 Authen::DecHpwd - DEC VMS password hashing
7
9 use Authen::DecHpwd qw(
10 UAI_C_AD_II UAI_C_PURDY UAI_C_PURDY_V UAI_C_PURDY_S
11 lgi_hpwd
12 );
13 $hash = lgi_hpwd("JRANDOM", "PASSWORD", UAI_C_PURDY_S, 1234);
15 use Authen::DecHpwd qw(vms_username vms_password);
17 $username = vms_username($username);
19 $password = vms_password($password);
20
22 This module implements the "SYS$HASH_PASSWORD" password hashing
23 function from VMS (also known as "LGI$HPWD"), and some associated VMS
24 username and password handling functions.
25 The password hashing function is implemented in XS, with a hideously
27 slow pure Perl backup version for systems that can't handle XS.
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30 UAI_C_AD_II
31 UAI_C_PURDY
32 UAI_C_PURDY_V
33 UAI_C_PURDY_S
34 These constants are used to identify the four password hashing
35 algorithms used by VMS. They are the "UAI$C_" constants in VMS.
36 "UAI_C_AD_II" refers to a 32-bit CRC algorithm. The CRC polynomial
38 used is the IEEE CRC-32 polynomial, as used in Ethernet, and in
39 this context is known as "AUTODIN-II". The hash is merely the CRC
40 of the password.
41 "UAI_C_PURDY", "UAI_C_PURDY_V", and "UAI_C_PURDY_S" refer to
43 successive refinements of an algorithm based on Purdy polynomials.
44 All of these algorithms use the salt and username parameters as
45 salt, use the whole password, and return an eight-byte (64-bit)
46 hash. The main part of the algorithm, the Purdy polynomial, is
47 identical in all three. They differ in the pre-hashing,
48 particularly in the treatment of the username parameter.
49 In "UAI_C_PURDY" the username is truncated or space-padded to 12
51 characters before being hashed in. "UAI_C_PURDY_V" accepts a
52 variable-length username. "UAI_C_PURDY_S" accepts a variable-
53 length username and also includes the password length in the hash.
54 "UAI_C_PURDY_S" also does some extra bit rotations when hashing in
55 the username and password strings, in order to avoid aliasing.
56 lgi_hpwd(USERNAME, PASSWORD, ALGORITHM, SALT)
58 This is the "SYS$HASH_PASSWORD" function from VMS (also known as
59 "LGI$HPWD"), but with the parameters in a different order. It
60 hashes the PASSWORD string in a manner determined by the other
61 parameters, and returns the hash as a string of bytes.
62 ALGORITHM determines which hashing algorithm will be used. It must
64 be the value of one of the algorithm constants supplied by this
65 module (see above).
66 SALT must be an integer in the range [0, 2^16). It modifies the
68 hashing so that the same password does not always produce the same
69 hash.
70 USERNAME is a string that is used as more salt. In VMS it is the
72 username of the account to which the password controls access.
73 VMS usernames and passwords are constrained in character set and
75 length, and are case-insensitive. This function does not enforce
76 these restrictions, nor perform canonicalisation. If restrictions
77 and canonicalisation are desired then they must be applied
78 separately. The functions "vms_username" and "vms_password"
79 described below may be useful.
80 vms_username(USERNAME)
82 Checks whether the USERNAME string matches VMS username syntax, and
83 canonicalises it. VMS username syntax is 1 to 31 characters from
84 case-insensitive alphanumerics, "_", and "$". If the string has
85 correct username syntax then the username is returned in canonical
86 form (uppercase). If the string is not a username then "undef" is
87 returned.
88 vms_password(PASSWORD)
90 Checks whether the PASSWORD string is an acceptable VMS password,
91 and canonicalises it. VMS password syntax is 1 to 32 characters
92 from case-insensitive alphanumerics, "_", and "$". If the string
93 is an acceptable password then the password is returned in
94 canonical form (uppercase). If the string is not an acceptable
95 password then "undef" is returned.
96
98 VMS::User
99
101 The original C implementation of "LGI$HPWD" was written by Shawn
102 Clifford. The code has since been developed by Davide Casale, Mario
103 Ambrogetti, Terence Lee, Jean-loup Gailly, Solar Designer, and Andrew
104 Main (Zefram).
105 Mike McCauley <mikem@open.com.au> created the first version of
107 "Authen::DecHpwd", establishing the Perl interface. This was based on
108 Shawn Clifford's code without the later developments.
109 Andrew Main (Zefram) <zefram@fysh.org> created a new "Authen::DecHpwd"
111 based on the more developed C code presently used, and added ancillary
112 functions.
113
115 Copyright (C) 2002 Jean-loup Gailly <http://gailly.net>
116 Based in part on code from John the Ripper, Copyright (C) 1996-2002
118 Solar Designer
119 Copyright (C) 2006, 2007, 2009, 2010, 2011, 2017 Andrew Main (Zefram)
121 <zefram@fysh.org>
122
124 This module is free software; you can redistribute it and/or modify it
125 under the terms of the GNU General Public License as published by the
126 Free Software Foundation; either version 2 of the License, or (at your
127 option) any later version.
128perl v5.34.0 2022-01-20 Authen::DecHpwd(3)