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Crypt::DSA(3pm) User Contributed Perl Documentation Crypt::DSA(3pm)
NAME
Crypt::DSA - DSA Signatures and Key Generation
SYNOPSIS
use Crypt::DSA;
my $dsa = Crypt::DSA->new;
my $key = $dsa->keygen(
Size => 512,
Seed => $seed,
Verbosity => 1
);
my $sig = $dsa->sign(
Message => "foo bar",
Key => $key
);
my $verified = $dsa->verify(
Message => "foo bar",
Signature => $sig,
Key => $key,
);
DESCRIPTION
Crypt::DSA is an implementation of the DSA (Digital Signature Algorithm) signature
verification system. The implementation itself is pure Perl, although the heavy-duty
mathematics underneath are provided by the Math::Pari library.
This package provides DSA signing, signature verification, and key generation.
USAGE
The Crypt::DSA public interface is similar to that of Crypt::RSA. This was done
intentionally.
Crypt::DSA->new
Constructs a new Crypt::DSA object. At the moment this isn't particularly useful in
itself, other than being the object you need to do much else in the system.
Returns the new object.
$key = $dsa->keygen(%arg)
Generates a new set of DSA keys, including both the public and private portions of the
key.
%arg can contain:
o Size
The size in bits of the p value to generate. The q and g values are always 160 bits
each.
This argument is mandatory.
o Seed
A seed with which q generation will begin. If this seed does not lead to a suitable
prime, it will be discarded, and a new random seed chosen in its place, until a
suitable prime can be found.
This is entirely optional, and if not provided a random seed will be generated
automatically.
o Verbosity
Should be either 0 or 1. A value of 1 will give you a progress meter during p and q
generation--this can be useful, since the process can be relatively long.
The default is 0.
$signature = $dsa->sign(%arg)
Signs a message (or the digest of a message) using the private portion of the DSA key and
returns the signature.
The return value--the signature--is a Crypt::DSA::Signature object.
%arg can include:
o Digest
A digest to be signed. The digest should be 20 bytes in length or less.
You must provide either this argument or Message (see below).
o Key
The Crypt::DSA::Key object with which the signature will be generated. Should contain
a private key attribute (priv_key).
This argument is required.
o Message
A plaintext message to be signed. If you provide this argument, sign will first
produce a SHA1 digest of the plaintext, then use that as the digest to sign. Thus
writing
my $sign = $dsa->sign(Message => $message, ... );
is a shorter way of writing
use Digest::SHA qw( sha1 );
my $sig = $dsa->sign(Digest => sha1( $message ), ... );
$verified = $dsa->verify(%arg)
Verifies a signature generated with sign. Returns a true value on success and false on
failure.
%arg can contain:
o Key
Key of the signer of the message; a Crypt::DSA::Key object. The public portion of the
key is used to verify the signature.
This argument is required.
o Signature
The signature itself. Should be in the same format as returned from sign, a
Crypt::DSA::Signature object.
This argument is required.
o Digest
The original signed digest whose length is less than or equal to 20 bytes.
Either this argument or Message (see below) must be present.
o Message
As above in sign, the plaintext message that was signed, a string of arbitrary length.
A SHA1 digest of this message will be created and used in the verification process.
TODO
Add ability to munge format of keys. For example, read/write keys from/to key files (SSH
key files, etc.), and also write them in other formats.
SUPPORT
Bugs should be reported via the CPAN bug tracker at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Crypt-DSA>
For other issues, contact the author.
AUTHOR
Benjamin Trott <ben AT sixapart.com>
COPYRIGHT
Except where otherwise noted, Crypt::DSA is Copyright 2006 - 2011 Benjamin Trott.
Crypt::DSA is free software; you may redistribute it and/or modify it under the same terms
as Perl itself.
perl v5.20.2 2015-10-24 Crypt::DSA(3pm)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
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