NAME

Crypt::Schnorr::AuthSign - Schnorr Authentication & Signature Protocols

VERSION

 $Revision: 1.10 $
 $Date: 2001/05/26 15:54:53 $

SYNOPSIS

  use Crypt::Schnorr::AuthSign;

  $schnorr = new Crypt::Schnorr::AuthSign;

  $schnorr->qsize(512);                   # Use a 512 bit modulus.

  $schnorr->keygen(Name => 'Test User');  # Create a new keypair.

  $req = $schnorr->authreq();             # Create auth request.
  $c = $schnorr->challenge($req);         # Generate auth challenge.
  $response = $schnorr->response($c);     # Respond to a challenge.
  $auth = $schnorr->verify($response);    # Verify auth response.

  $sign = $schnorr->sign($m);             # Create a signature for $m.
  $valid = $schnorr->verify($sign, $m);   # Verify signature on $m.

DESCRIPTION

This module implements the basic Schnorr authentication and signature protocols. It supports zlib compression, Radix64 encoding for exported keys and protocol packets, and a simple method for binding metadata to keys. It does not provide any key management functions or maintain a key database.

CONSTRUCTOR

new()

Creates and returns a new Crypt::Schnorr::AuthSign object.

DATA METHODS

qsize()

Sets the QSIZE instance variable which can be used to change the bitlength of the prime 'q' which is the modulus for most of the calculations in the protocol. A smaller prime, 'p' (q=pk+1) is also used - its bitlength is dependent on the choice of q.

secretkey()

If called without parameters, returns the Crypt::Schnorr::Key object corresponding to the active secret key. If passed a Crypt::Schnorr::Key object, makes that key the currently active secret key.

pubkey()

If called without parameters, returns the Crypt::Schnorr::Key object corresponding to the active public key. If passed a Crypt::Schnorr::Key object, makes that key the currently active public key.

version()

Sets the VERSION instance variable which can be used to change the Version: string on the generated protocol packets to whatever you like. If called without parameters, simply returns the value of the VERSION instance variable.

comment()

Sets the COMMENT instance variable which can be used to change the Comment: string on the generated protocol packets to whatever you like. If called without parameters, simply returns the value of the COMMENT instance variable.

debug()

Sets the DEBUG instance variable which causes the module to emit debugging information if set to a true value. If called without parameters, simply returns the value of the DEBUG instance variable.

hash()

Sets or fetches the HASH instance variable - a coderef. The referenced routine should compute a message digest of it's first argument and return the digest as a decimal or hex number.

OBJECT METHODS

keygen(%metainfo)

Generates new public key parameters, creates a new keypair, and binds the name/value pairs of %metainfo with it. Sets the active secret and public keys to the generated keypair. Returns undef if there was an error, otherwise returns a filehandle that reports the progress of the key generation process.

authreq()

Creates and returns an authorization request. Saves parameters associated with the request for use in the rest of the authorization protocol.

challenge($authreq)

Generates and returns a challenge to the authorization request in $authreq, and saves the request parameters for use in the rest of the authorization protocol.

response($challenge)

Generates and returns a response to the authorization challenge in $challenge, using some of the information saved by the last call to authreq().

sign($message)

Computes a message digest of $message, and returns a signature on this message digest. The message digest is computed using the default hash routine (SHA1 with Digest::SHA1) or the hash routine set with the last call to hash().

verify($response)

Attempts to verify the response packet $response against the currently active public key, which should previously have been set by a call to pubkey() or some other method. Returns true iff the authorization succeeded.

KEY OBJECT METHODS

new($keypacket)

Creates a new Crypt::Schnorr::Key object and initializes it from the key information in $keypacket. The $keypacket argument is required.

export()

Returns a Radix64 encoded representation of the key.

meta()

Allows metadata access. Provide a label to retrieve the value associated with it, provide a label/value pair and it will be associated with the key, replacing the old value if metadata with the specified label already exists. If called without parameters, will return a list containing all metadata key/value pairs.

AUTHOR

Crypt::Schnorr::AuthSign is Copyright (c) 2001 Ashish Gulhati <hash@netropolis.org>. All Rights Reserved.

LICENSE

This code is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

DISCLAIMER

This is free software. If it breaks, you own both parts.