Package gnu.crypto.key

Provides a basic API for algorithms to generate Public/Private keypairs, and Key Agreement schemes.

See:
Description

Interface Summary

IKeyAgreementParty	The visible methods of an key agreement protocol participating party.
IKeyPairCodec	The visible methods of an object that knows how to encode and decode cryptographic asymmetric keypairs.
IKeyPairGenerator	The visible methods of every asymmetric keypair generator.

Class Summary

BaseKeyAgreementParty	A base abstract class to facilitate implementations of concrete key agreement protocol handlers.
IncomingMessage	An implementation of an incoming message for use with key agreement protocols.
KeyAgreementFactory	A Factory class to generate key agreement protocol handlers.
KeyPairCodecFactory	A Factory class to instantiate key encoder/decoder instances.
KeyPairGeneratorFactory	A Factory to instantiate asymmetric keypair generators.
OutgoingMessage	An implementation of outgoing messages for use with key agreement protocols.

Exception Summary

KeyAgreementException

A generic exception indicating that an unexpected condition has been detected during the setup and/or processing of a key agreement protocol exchange.

Package gnu.crypto.key Description

Provides a basic API for algorithms to generate Public/Private keypairs, and Key Agreement schemes.

Package overview

The contents of this package hierarchy is organised as follows:

• interfaces that describe the visible methods of concrete implementations of those interfaces,
• Factory classes that generate specific instances given a canonical name.
• common classes used by two or more concrete implementations,
• separate sub-packages for each implemented algorithm.

The four key-pair generation algorithms currently implemented in this library are:

• Diffie-Hellman: gnu.crypto.key.dh,
• Digital Signature Scheme: gnu.crypto.key.dss,
• Rivest, Shamir and Adleman (RSA): gnu.crypto.key.rsa,
• Secure Remote Password 6: gnu.crypto.key.srp6.

The Key Agreement protocols currently implemented in this library are:

• Diffie-Hellman
  1. Basic version: also described in RFC-2631 as Static-Static mode, and
  2. ElGamal version: also known as half-certified Diffie-Hellman, or Ephemeral-Static mode in RFC-2631.
• Secure Remote Password
  1. Basic version: described, by Thomas J. Wu, in SRP Protocol Design, and
  2. The version adopted for use as a SASL (Simple Authentication and Security Layer) mechanism in the internet draft Secure Remote Password Authentication Mechanism.

The following diagram shows the important classes participating in key-pair generation:

The next diagram shows the important classes participating in key agreements:

The next two diagrams show the sequences involved in generating a keypair, and establishing a key agreement protocol.

The following example shows the code that can be used to generate a key- pair:

import gnu.crypto.sig.rsa.RSA;
import gnu.crypto.key.rsa.RSAKeyPairGenerator;

import java.math.BigInteger;
import java.security.KeyPair;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPrivateCrtKey;
import java.security.interfaces.RSAPublicKey;
import java.util.HashMap;
import java.util.Random;

...
RSAKeyPairGenerator kpg = new RSAKeyPairGenerator();
HashMap map = new HashMap();
map.put(RSAKeyPairGenerator.MODULUS_LENGTH, new Integer(1024));
kpg.setup(map);

KeyPair kp = kpg.generate();

BigInteger n1 = ((RSAPublicKey) kp.getPublic()).getModulus();
BigInteger e =  ((RSAPublicKey) kp.getPublic()).getPublicExponent();

BigInteger n2 = ((RSAPrivateKey) kp.getPrivate()).getModulus();
BigInteger d =  ((RSAPrivateKey) kp.getPrivate()).getPrivateExponent();

BigInteger p =    ((RSAPrivateCrtKey) kp.getPrivate()).getPrimeP();
BigInteger q =    ((RSAPrivateCrtKey) kp.getPrivate()).getPrimeQ();
BigInteger dP =   ((RSAPrivateCrtKey) kp.getPrivate()).getPrimeExponentP();
BigInteger dQ =   ((RSAPrivateCrtKey) kp.getPrivate()).getPrimeExponentQ();
BigInteger qInv = ((RSAPrivateCrtKey) kp.getPrivate()).getCrtCoefficient();