| /* DiffieHellmanKeyAgreement.java -- |
| Copyright (C) 2003, 2006 Free Software Foundation, Inc. |
| |
| This file is a part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or (at |
| your option) any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; if not, write to the Free Software |
| Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 |
| USA |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.javax.crypto.key.dh; |
| |
| import gnu.java.security.Registry; |
| import gnu.java.security.util.Util; |
| |
| import gnu.javax.crypto.key.BaseKeyAgreementParty; |
| import gnu.javax.crypto.key.KeyAgreementException; |
| |
| import java.math.BigInteger; |
| |
| import javax.crypto.interfaces.DHPrivateKey; |
| |
| /** |
| * The basic version of the Diffie-Hellman key agreement is described in the |
| * Handbook of Applied Cryptography [HAC] as follows: |
| * <ul> |
| * <li>An appropriate prime p and generator g of Z<sub>p</sub><sup>*</sup> |
| * (2 <= g <= p-2) are selected and published.</li> |
| * <li>A and B each send the other one message over an open channel; as a |
| * result, they both can then compute a shared secret key K which they can use |
| * to protect their future communication.</li> |
| * <li>A chooses a random secret x, 1 <= x <= p-2, and sends B message |
| * (1) which is g^x mod p.</li> |
| * <li>B chooses a random secret y, 1 <= y <= p-2, and sends A message |
| * (2) which is g^y mod p.</li> |
| * <li>B receives message (1) and computes the shared key as K = (g^x)^y mod p. |
| * </li> |
| * <li>A receives message (2) and computes the shared key as K = (g^y)^x mod p. |
| * </li> |
| * </ul> |
| * <p> |
| * RFC-2631 describes a <i>Static-Static Mode</i> of operations with |
| * Diffie-Hellman keypairs as follows: |
| * <pre> |
| * "In Static-Static mode, both the sender and the recipient have a |
| * static (and certified) key pair. Since the sender's and recipient's |
| * keys are therefore the same for each message, ZZ will be the same for |
| * each message. Thus, partyAInfo MUST be used (and different for each |
| * message) in order to ensure that different messages use different |
| * KEKs. Implementations MAY implement Static-Static mode." |
| * </pre> |
| * |
| * <p> |
| * Reference: |
| * <ol> |
| * <li><a href="http://www.ietf.org/rfc/rfc2631.txt">Diffie-Hellman Key |
| * Agreement Method</a><br> |
| * Eric Rescorla.</li> |
| * <li><a href="http://www.cacr.math.uwaterloo.ca/hac">[HAC]</a>: Handbook of |
| * Applied Cryptography.<br> |
| * CRC Press, Inc. ISBN 0-8493-8523-7, 1997<br> |
| * Menezes, A., van Oorschot, P. and S. Vanstone.</li> |
| * </ol> |
| */ |
| public abstract class DiffieHellmanKeyAgreement |
| extends BaseKeyAgreementParty |
| { |
| public static final String SOURCE_OF_RANDOMNESS = "gnu.crypto.dh.ka.prng"; |
| public static final String KA_DIFFIE_HELLMAN_OWNER_PRIVATE_KEY = |
| "gnu.crypto.dh.ka.owner.private.key"; |
| /** The key agreement party's private key. */ |
| protected DHPrivateKey ownerKey; |
| /** The shared secret key. */ |
| protected BigInteger ZZ; |
| |
| protected DiffieHellmanKeyAgreement() |
| { |
| super(Registry.DH_KA); |
| } |
| |
| protected byte[] engineSharedSecret() throws KeyAgreementException |
| { |
| return Util.trim(ZZ); |
| } |
| |
| protected void engineReset() |
| { |
| ownerKey = null; |
| ZZ = null; |
| } |
| } |