1Crypt::DSA(3) User Contributed Perl Documentation Crypt::DSA(3)
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6 Crypt::DSA - DSA Signatures and Key Generation
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9 use Crypt::DSA;
10 my $dsa = Crypt::DSA->new;
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12 my $key = $dsa->keygen(
13 Size => 512,
14 Seed => $seed,
15 Verbosity => 1
16 );
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18 my $sig = $dsa->sign(
19 Message => "foo bar",
20 Key => $key
21 );
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23 my $verified = $dsa->verify(
24 Message => "foo bar",
25 Signature => $sig,
26 Key => $key,
27 );
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30 Crypt::DSA is an implementation of the DSA (Digital Signature
31 Algorithm) signature verification system. The implementation itself is
32 pure Perl, although the heavy-duty mathematics underneath are provided
33 by the Math::Pari library.
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35 This package provides DSA signing, signature verification, and key
36 generation.
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39 The Crypt::DSA public interface is similar to that of Crypt::RSA. This
40 was done intentionally.
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42 Crypt::DSA->new
43 Constructs a new Crypt::DSA object. At the moment this isn't
44 particularly useful in itself, other than being the object you need to
45 do much else in the system.
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47 Returns the new object.
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49 $key = $dsa->keygen(%arg)
50 Generates a new set of DSA keys, including both the public and private
51 portions of the key.
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53 %arg can contain:
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55 · Size
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57 The size in bits of the p value to generate. The q and g values are
58 always 160 bits each.
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60 This argument is mandatory.
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62 · Seed
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64 A seed with which q generation will begin. If this seed does not
65 lead to a suitable prime, it will be discarded, and a new random
66 seed chosen in its place, until a suitable prime can be found.
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68 This is entirely optional, and if not provided a random seed will
69 be generated automatically.
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71 · Verbosity
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73 Should be either 0 or 1. A value of 1 will give you a progress
74 meter during p and q generation--this can be useful, since the
75 process can be relatively long.
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77 The default is 0.
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79 $signature = $dsa->sign(%arg)
80 Signs a message (or the digest of a message) using the private portion
81 of the DSA key and returns the signature.
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83 The return value--the signature--is a Crypt::DSA::Signature object.
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85 %arg can include:
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87 · Digest
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89 A digest to be signed. The digest should be 20 bytes in length or
90 less.
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92 You must provide either this argument or Message (see below).
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94 · Key
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96 The Crypt::DSA::Key object with which the signature will be
97 generated. Should contain a private key attribute (priv_key).
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99 This argument is required.
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101 · Message
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103 A plaintext message to be signed. If you provide this argument,
104 sign will first produce a SHA1 digest of the plaintext, then use
105 that as the digest to sign. Thus writing
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107 my $sign = $dsa->sign(Message => $message, ... );
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109 is a shorter way of writing
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111 use Digest::SHA1 qw( sha1 );
112 my $sig = $dsa->sign(Digest => sha1( $message ), ... );
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114 $verified = $dsa->verify(%arg)
115 Verifies a signature generated with sign. Returns a true value on
116 success and false on failure.
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118 %arg can contain:
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120 · Key
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122 Key of the signer of the message; a Crypt::DSA::Key object. The
123 public portion of the key is used to verify the signature.
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125 This argument is required.
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127 · Signature
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129 The signature itself. Should be in the same format as returned from
130 sign, a Crypt::DSA::Signature object.
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132 This argument is required.
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134 · Digest
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136 The original signed digest whose length is less than or equal to 20
137 bytes.
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139 Either this argument or Message (see below) must be present.
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141 · Message
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143 As above in sign, the plaintext message that was signed, a string
144 of arbitrary length. A SHA1 digest of this message will be created
145 and used in the verification process.
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148 Add ability to munge format of keys. For example, read/write keys
149 from/to key files (SSH key files, etc.), and also write them in other
150 formats.
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153 Bugs should be reported via the CPAN bug tracker at
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155 <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Crypt-DSA>
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157 For other issues, contact the author.
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160 Benjamin Trott <ben@sixapart.com>
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163 Except where otherwise noted, Crypt::DSA is Copyright 2006 - 2011
164 Benjamin Trott.
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166 Crypt::DSA is free software; you may redistribute it and/or modify it
167 under the same terms as Perl itself.
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171perl v5.30.0 2019-07-26 Crypt::DSA(3)