1Crypt::RandPasswd(3) User Contributed Perl Documentation Crypt::RandPasswd(3)
2
6 Crypt::RandPasswd - random password generator based on FIPS-181
7
9 use Crypt::RandPasswd;
10 ( $word, $hyphenated ) = Crypt::RandPasswd->word( $minlen, $maxlen );
11 $word = Crypt::RandPasswd->word( $minlen, $maxlen );
12 $word = Crypt::RandPasswd->letters( $minlen, $maxlen );
13 $word = Crypt::RandPasswd->chars( $minlen, $maxlen );
14 # override the defaults for these functions:
16 *Crypt::RandPasswd::rng = \&my_random_number_generator;
17 *Crypt::RandPasswd::restrict = \&my_restriction_filter;
18
20 Crypt::RandPasswd provides three functions that can be used to generate
21 random passwords, constructed from words, letters, or characters.
22 This code is a Perl implementation of the Automated Password Generator
24 standard, like the program described in "A Random Word Generator For
25 Pronounceable Passwords" (not available on-line). This code is a re-
26 engineering of the program contained in Appendix A of FIPS Publication
27 181, "Standard for Automated Password Generator". In accordance with
28 the standard, the results obtained from this program are logically
29 equivalent to those produced by the standard.
30
32 Bugs
33 The function to generate a password can sometimes take an extremely
34 long time.
35 Deviations From Standard
37 This implementation deviates in one critical way from the standard upon
38 which it is based: the random number generator in this implementation
39 does not use DES. Instead, it uses perl's built-in "rand()" function,
40 which in turn is (usually) built on the pseudo-random number generator
41 functions of the underlying C library.
42 However, the random function can be replaced by the user if desired.
44 (See "rng".)
45
47 word
48 word = word( minlen, maxlen );
49 ( word, hyphenated_form ) = word( minlen, maxlen );
50 Generates a random word, as well as its hyphenated form. The length of
52 the returned word will be between minlen and maxlen.
53 letters
55 word = letters( minlen, maxlen );
56 Generates a string of random letters. The length of the returned word
58 is between minlen and maxlen. Calls "random_chars_in_range( 'a' => 'z'
59 )".
60 chars
62 word = chars( minlen, maxlen );
63 Generates a string of random printable characters. The length of the
65 returned word is between minlen and maxlen. Calls
66 "random_chars_in_range( '!' => '~' )".
67 random_chars_in_range
69 word = random_chars_in_range( minlen, maxlen, lo_char => hi_char );
70 Generates a string of printable characters. The length of the returned
72 string is between minlen and maxlen. Each character is selected from
73 the range of ASCII characters delimited by (lo_char,hi_char).
74 rand_int_in_range
76 n = rand_int_in_range( min, max );
77 Returns an integer between min and max, inclusive. Calls "rng" like
79 so:
80 n = min + int( rng( max - min + 1 ) )
82 random_element
84 e = random_element( \@elts )
85 Selects a random element from an array, which is passed by ref.
87 rng
89 r = rng( n );
90 "rng" is designed to have the same interface as the built-in "rand"
92 function. The default implementation here is a simple wrapper around
93 "rand", which is typically a wrapper for some pseudo-random number
94 function in the underlying C library.
95 The reason for having this simple wrapper is so the user can easily
97 substitute a different random number generator if desired. Since many
98 rng's have the same interface as "rand", replacing "rng()" is as simple
99 as
100 {
102 local $^W; # squelch sub redef warning.
103 *Crypt::RandPasswd::rng = \&my_rng;
104 }
105 See rand.
107 restrict
109 word = restrict( word );
110 A filter. Returns the arg unchanged if it is allowable; returns undef
112 if not.
113 The default version of "restrict()" allows everything. You may install
115 a different form to implement other restrictions, by doing something
116 like this:
117 {
119 local $^W; # squelch sub redef warning.
120 *Crypt::RandPasswd::restrict = \&my_filter;
121 }
122 init
124 This initializes the environment, which by default simply seeds the
125 random number generator.
126 get_syllable
128 Generate next unit to password, making sure that it follows these
129 rules:
130 1. Each syllable must contain exactly 1 or 2 consecutive vowels, where
132 y is considered a vowel.
133 2. Syllable end is determined as follows:
135 a. Vowel is generated and previous unit is a consonant and syllable already has a vowel.
137 In this case, new syllable is started and already contains a vowel.
138 b. A pair determined to be a "break" pair is encountered.
139 In this case new syllable is started with second unit of this pair.
140 c. End of password is encountered.
141 d. "begin" pair is encountered legally. New syllable is started with this pair.
142 e. "end" pair is legally encountered. New syllable has nothing yet.
143 3. Try generating another unit if:
145 a. third consecutive vowel and not y.
147 b. "break" pair generated but no vowel yet in current or previous 2 units are "not_end".
148 c. "begin" pair generated but no vowel in syllable preceding begin pair,
149 or both previous 2 pairs are designated "not_end".
150 d. "end" pair generated but no vowel in current syllable or in "end" pair.
151 e. "not_begin" pair generated but new syllable must begin (because previous syllable ended as defined in 2 above).
152 f. vowel is generated and 2a is satisfied, but no syllable break is possible in previous 3 pairs.
153 g. Second and third units of syllable must begin, and first unit is "alternate_vowel".
154
156 CPAN modules for generating passwords
157 <http://neilb.org/reviews/passwords.html> - a review of modules of CPAN
158 for random password generation.
159 Some of the better modules: App::Genpass, Crypt::XkcdPassword,
161 Crypt::YAPassGen, Data::Random, String::Random.
162 FIPS 181 - (APG), Automated Password Generator:
164 http://www.itl.nist.gov/fipspubs/fip181.htm
165
167 <https://github.com/neilbowers/Crypt-RandPasswd>
168
170 JDPORTER@cpan.org (John Porter)
171 Now maintained by Neil Bowers <neilb@cpan.org>
173
175 This perl module is free software; it may be redistributed and/or
176 modified under the same terms as Perl itself.
177perl v5.30.0 2019-07-26 Crypt::RandPasswd(3)