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:

• 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.

• 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.

• 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:

• 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).

• 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.

• 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:

• 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.

• Signature

  The signature itself. Should be in the same format as returned from sign, a Crypt::DSA::Signature object.

  This argument is required.

• 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.

• 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.