| /* DiffieHellmanImpl.java -- implementation of the Diffie-Hellman key agreement. |
| Copyright (C) 2005, 2006 Free Software Foundation, Inc. |
| |
| This file is 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, 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; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, 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.jce; |
| |
| import java.math.BigInteger; |
| import java.security.InvalidKeyException; |
| import java.security.Key; |
| import java.security.SecureRandom; |
| import java.security.spec.AlgorithmParameterSpec; |
| |
| import javax.crypto.KeyAgreementSpi; |
| import javax.crypto.SecretKey; |
| import javax.crypto.ShortBufferException; |
| import javax.crypto.interfaces.DHPrivateKey; |
| import javax.crypto.interfaces.DHPublicKey; |
| import javax.crypto.spec.DHParameterSpec; |
| import javax.crypto.spec.SecretKeySpec; |
| |
| /** |
| * The JCE implementation of a 2-party Diffie-Hellman key agreement. |
| * |
| * @author Casey Marshall (csm@gnu.org) |
| */ |
| public final class DiffieHellmanImpl |
| extends KeyAgreementSpi |
| { |
| /** The private key being used for this agreement. */ |
| private DHPrivateKey key; |
| |
| /** The current result. */ |
| private byte[] result; |
| |
| /** True if the caller told us we are done. */ |
| private boolean last_phase_done; |
| |
| /** Trivial default constructor. */ |
| public DiffieHellmanImpl() |
| { |
| super(); |
| |
| key = null; |
| result = null; |
| last_phase_done = false; |
| } |
| |
| protected Key engineDoPhase(Key incoming, boolean lastPhase) |
| throws InvalidKeyException |
| { |
| if (key == null) |
| throw new IllegalStateException("Not initialized"); |
| |
| if (last_phase_done) |
| throw new IllegalStateException("Last phase already done"); |
| |
| if (! (incoming instanceof DHPublicKey)) |
| throw new InvalidKeyException("Key MUST be a DHPublicKey"); |
| |
| DHPublicKey pub = (DHPublicKey) incoming; |
| DHParameterSpec s1 = key.getParams(); |
| DHParameterSpec s2 = pub.getParams(); |
| if (! s1.getG().equals(s2.getG()) || ! s1.getP().equals(s2.getP()) |
| || s1.getL() != s2.getL()) |
| throw new InvalidKeyException("Incompatible key"); |
| if (! lastPhase) |
| throw new IllegalArgumentException( |
| "This key-agreement MUST be concluded in one step only"); |
| BigInteger resultBI = pub.getY().modPow(key.getX(), s1.getP()); |
| result = resultBI.toByteArray(); |
| if (result[0] == 0x00) |
| { |
| byte[] buf = new byte[result.length - 1]; |
| System.arraycopy(result, 1, buf, 0, buf.length); |
| result = buf; |
| } |
| last_phase_done = true; |
| return null; |
| } |
| |
| protected byte[] engineGenerateSecret() |
| { |
| checkState(); |
| byte[] res = (byte[]) result.clone(); |
| reset(); |
| return res; |
| } |
| |
| protected int engineGenerateSecret(byte[] secret, int offset) |
| throws ShortBufferException |
| { |
| checkState(); |
| if (result.length > secret.length - offset) |
| throw new ShortBufferException(); |
| System.arraycopy(result, 0, secret, offset, result.length); |
| int res = result.length; |
| reset(); |
| return res; |
| } |
| |
| protected SecretKey engineGenerateSecret(String algorithm) |
| throws InvalidKeyException |
| { |
| checkState(); |
| byte[] s = (byte[]) result.clone(); |
| SecretKey res = new SecretKeySpec(s, algorithm); |
| reset(); |
| return res; |
| } |
| |
| protected void engineInit(Key key, SecureRandom random) |
| throws InvalidKeyException |
| { |
| if (! (key instanceof DHPrivateKey)) |
| throw new InvalidKeyException("Key MUST be a DHPrivateKey"); |
| this.key = (DHPrivateKey) key; |
| reset(); |
| } |
| |
| protected void engineInit(Key key, AlgorithmParameterSpec params, |
| SecureRandom random) |
| throws InvalidKeyException |
| { |
| engineInit(key, random); |
| } |
| |
| private void reset() |
| { |
| result = null; |
| last_phase_done = false; |
| } |
| |
| private void checkState() |
| { |
| if (result == null || ! last_phase_done) |
| throw new IllegalStateException("Not finished"); |
| } |
| } |