1Crypt::UnixCrypt_XS(3)User Contributed Perl DocumentationCrypt::UnixCrypt_XS(3)
2
6 Crypt::UnixCrypt_XS - perl xs interface for a portable traditional
7 crypt function.
8
10 use Crypt::UnixCrypt_XS qw/crypt/;
11 my $hashed = crypt( $password, $salt );
12 use Crypt::UnixCrypt_XS qw/crypt_rounds fold_password
14 base64_to_block block_to_base64
15 base64_to_int24 int24_to_base64
16 base64_to_int12 int12_to_base64/;
17 $block = crypt_rounds( $password, $nrounds, $saltnum, $block );
18 $password = fold_password( $password );
19 $block = base64_to_block( $base64 );
20 $base64 = block_to_base64( $block );
21 $saltnum = base64_to_int24( $base64 );
22 $base64 = int24_to_base64( $saltnum );
23 $saltnum = base64_to_int12( $base64 );
24 $base64 = int12_to_base64( $saltnum );
25
27 This module implements the DES-based Unix crypt function. For those
28 who need to construct non-standard variants of crypt, the various
29 building blocks used in crypt are also supplied separately.
30
32 crypt( PASSWORD, SALT )
33 This is the conventional crypt interface. PASSWORD and SALT are
34 both strings. The password will be hashed, in a manner determined
35 by the salt, and a string is returned containing the salt and hash.
36 The salt is at the beginning of the returned string, and only the
37 beginning of the salt string is examined, so it is acceptable to
38 use a string returned by crypt as a salt argument. Three different
39 types of hashing may occur:
40 If the salt is an empty string, then the password is ignored and an
42 empty string is returned. The empty salt/hash string is thus used
43 to not require a password.
44 If the salt string starts with two base 64 digits (from the set
46 [./0-9A-Za-z]), then the password is hashed using the traditional
47 DES-based algorithm. The salt is used to modify the DES algorithm
48 in one of 4096 different ways. The first eight characters of the
49 password are used as a DES key, to encrypt a block of zeroes
50 through 25 iterations of the modified DES. The block output by the
51 final iteration is the hash, and it is returned in base 64 (as
52 eleven digits).
53 If the salt string starts with an underscore character and then
55 eight base 64 digits then the password is hashed using the extended
56 DES-based algorithm from BSDi. The first four base 64 digits
57 specify how many encryption rounds are to be performed. The next
58 four base 64 digits are used to modify the DES algorithm in one of
59 16777216 different ways. If the password is longer than eight
60 characters, it is hashed down to eight characters before being used
61 as a key, so all characters of the password are significant.
62 crypt_rounds( PASSWORD, NROUNDS, SALTNUM, BLOCK )
64 This is the core of the DES-based crypt algorithm, exposed here to
65 allow variant hash functions to be built. PASSWORD is a string;
66 its first eight characters are used as a DES key. SALTNUM is an
67 integer; its low 24 bits are used to modify the DES algorithm.
68 BLOCK must be a string exactly eight bytes long. The data block is
69 passed through NROUNDS iterations of the modified DES, and the
70 final output block (also a string of exactly eight bytes) is
71 returned.
72 fold_password( PASSWORD )
74 This is the pre-hashing algorithm used in the extended DES
75 algorithm to fold a long password to the size of a DES key. It
76 takes a password of any length, and returns a password of eight
77 characters which is completely equivalent in the extended DES
78 algorithm. Note: the password returned may contain NUL characters.
79 The functions in this module correctly handle NULs in password
80 strings, but a normal C library crypt cannot. If you need the
81 short password to contain no NULs, perform the substitution
82 "s/\0/\x80/g": the top bit of each password character is ignored,
83 so the result is equivalent.
84 base64_to_block( BASE64 )
86 This converts a data block from a string of eleven base 64 digits
87 to a raw string of eight bytes.
88 block_to_base64( BLOCK )
90 This converts a data block from a raw string of eight bytes to a
91 string of eleven base 64 digits.
92 base64_to_int24( BASE64 )
94 This converts a 24-bit integer from a string of four base 64 digits
95 to a Perl integer.
96 int24_to_base64( VALUE )
98 This converts a 24-bit integer from a Perl integer to a string of
99 four base 64 digits.
100 base64_to_int12( BASE64 )
102 This converts a 12-bit integer from a string of two base 64 digits
103 to a Perl integer.
104 int12_to_base64( VALUE )
106 This converts a 12-bit integer from a Perl integer to a string of
107 two base 64 digits.
108 EXPORT
110 None by default.
111
113 Crypt::UnixCrypt_XS provide a fast portable crypt function. Perl's
114 internal crypt is not present at every system. Perl calls the crypt
115 function of the system's C library. This may lead to trouble if the
116 system's crypt presents different results for the same key and salt,
117 but different processid's. Crypt::UnixCrypt is the cure here, but it is
118 to slow. On my computer Crypt::UnixCrypt_XS is about 800 times faster
119 than Crypt::UnixCrypt.
120
122 crypt(3), Crypt::UnixCrypt
123
125 Boris Zentner, <bzm@2bz.de>, the original C source code was written by
126 Eric Young, eay@psych.uq.oz.au.
127
129 Fixes, Bug Reports, Docs have been generously provided by:
130 Andrew Main (Zefram) <zefram@fysh.org>
132 Guenter Knauf
133 Thanks!
134
136 Copyright (C) 2004, 2005, 2006, 2007 by Boris Zentner
137 This library is free software; you can redistribute it and/or modify it
139 under the same terms as Perl itself, either Perl version 5.8.3 or, at
140 your option, any later version of Perl 5 you may have available.
141perl v5.30.0 2019-07-26 Crypt::UnixCrypt_XS(3)