| /* |
| * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package com.sun.crypto.provider; |
| |
| import java.math.BigInteger; |
| import java.security.*; |
| import java.security.spec.AlgorithmParameterSpec; |
| import java.security.spec.InvalidParameterSpecException; |
| import javax.crypto.spec.DHParameterSpec; |
| import javax.crypto.spec.DHGenParameterSpec; |
| |
| import sun.security.provider.ParameterCache; |
| |
| /** |
| * This class represents the key pair generator for Diffie-Hellman key pairs. |
| * |
| * <p>This key pair generator may be initialized in two different ways: |
| * |
| * <ul> |
| * <li>By providing the size in bits of the prime modulus - |
| * This will be used to create a prime modulus and base generator, which will |
| * then be used to create the Diffie-Hellman key pair. The default size of the |
| * prime modulus is 2048 bits. |
| * <li>By providing a prime modulus and base generator |
| * </ul> |
| * |
| * @author Jan Luehe |
| * |
| * |
| * @see java.security.KeyPairGenerator |
| */ |
| public final class DHKeyPairGenerator extends KeyPairGeneratorSpi { |
| |
| // parameters to use or null if not specified |
| private DHParameterSpec params; |
| |
| // The size in bits of the prime modulus |
| private int pSize; |
| |
| // The size in bits of the random exponent (private value) |
| private int lSize; |
| |
| // The source of randomness |
| private SecureRandom random; |
| |
| public DHKeyPairGenerator() { |
| super(); |
| initialize(2048, null); |
| } |
| |
| private static void checkKeySize(int keysize) |
| throws InvalidParameterException { |
| |
| if ((keysize < 512) || (keysize > 8192) || ((keysize & 0x3F) != 0)) { |
| throw new InvalidParameterException( |
| "DH key size must be multiple of 64, and can only range " + |
| "from 512 to 8192 (inclusive). " + |
| "The specific key size " + keysize + " is not supported"); |
| } |
| } |
| |
| /** |
| * Initializes this key pair generator for a certain keysize and source of |
| * randomness. |
| * The keysize is specified as the size in bits of the prime modulus. |
| * |
| * @param keysize the keysize (size of prime modulus) in bits |
| * @param random the source of randomness |
| */ |
| public void initialize(int keysize, SecureRandom random) { |
| checkKeySize(keysize); |
| |
| // Use the built-in parameters (ranging from 512 to 8192) |
| // when available. |
| this.params = ParameterCache.getCachedDHParameterSpec(keysize); |
| |
| // Due to performance issue, only support DH parameters generation |
| // up to 1024 bits. |
| if ((this.params == null) && (keysize > 1024)) { |
| throw new InvalidParameterException( |
| "Unsupported " + keysize + "-bit DH parameter generation"); |
| } |
| |
| this.pSize = keysize; |
| this.lSize = 0; |
| this.random = random; |
| } |
| |
| /** |
| * Initializes this key pair generator for the specified parameter |
| * set and source of randomness. |
| * |
| * <p>The given parameter set contains the prime modulus, the base |
| * generator, and optionally the requested size in bits of the random |
| * exponent (private value). |
| * |
| * @param algParams the parameter set used to generate the key pair |
| * @param random the source of randomness |
| * |
| * @exception InvalidAlgorithmParameterException if the given parameters |
| * are inappropriate for this key pair generator |
| */ |
| public void initialize(AlgorithmParameterSpec algParams, |
| SecureRandom random) throws InvalidAlgorithmParameterException { |
| if (!(algParams instanceof DHParameterSpec)){ |
| throw new InvalidAlgorithmParameterException |
| ("Inappropriate parameter type"); |
| } |
| |
| params = (DHParameterSpec)algParams; |
| pSize = params.getP().bitLength(); |
| try { |
| checkKeySize(pSize); |
| } catch (InvalidParameterException ipe) { |
| throw new InvalidAlgorithmParameterException(ipe.getMessage()); |
| } |
| |
| // exponent size is optional, could be 0 |
| lSize = params.getL(); |
| |
| // Require exponentSize < primeSize |
| if ((lSize != 0) && (lSize > pSize)) { |
| throw new InvalidAlgorithmParameterException |
| ("Exponent size must not be larger than modulus size"); |
| } |
| this.random = random; |
| } |
| |
| /** |
| * Generates a key pair. |
| * |
| * @return the new key pair |
| */ |
| public KeyPair generateKeyPair() { |
| if (random == null) { |
| random = SunJCE.getRandom(); |
| } |
| |
| if (params == null) { |
| try { |
| params = ParameterCache.getDHParameterSpec(pSize, random); |
| } catch (GeneralSecurityException e) { |
| // should never happen |
| throw new ProviderException(e); |
| } |
| } |
| |
| BigInteger p = params.getP(); |
| BigInteger g = params.getG(); |
| |
| if (lSize <= 0) { |
| lSize = pSize >> 1; |
| // use an exponent size of (pSize / 2) but at least 384 bits |
| if (lSize < 384) { |
| lSize = 384; |
| } |
| } |
| |
| BigInteger x; |
| BigInteger pMinus2 = p.subtract(BigInteger.TWO); |
| |
| // |
| // PKCS#3 section 7.1 "Private-value generation" |
| // Repeat if either of the followings does not hold: |
| // 0 < x < p-1 |
| // 2^(lSize-1) <= x < 2^(lSize) |
| // |
| do { |
| // generate random x up to 2^lSize bits long |
| x = new BigInteger(lSize, random); |
| } while ((x.compareTo(BigInteger.ONE) < 0) || |
| ((x.compareTo(pMinus2) > 0)) || (x.bitLength() != lSize)); |
| |
| // calculate public value y |
| BigInteger y = g.modPow(x, p); |
| |
| DHPublicKey pubKey = new DHPublicKey(y, p, g, lSize); |
| DHPrivateKey privKey = new DHPrivateKey(x, p, g, lSize); |
| return new KeyPair(pubKey, privKey); |
| } |
| } |