| /* GENERATED SOURCE. DO NOT MODIFY. */ |
| package com.android.org.bouncycastle.crypto.generators; |
| |
| import java.math.BigInteger; |
| import java.security.SecureRandom; |
| |
| import com.android.org.bouncycastle.crypto.AsymmetricCipherKeyPair; |
| import com.android.org.bouncycastle.crypto.AsymmetricCipherKeyPairGenerator; |
| import com.android.org.bouncycastle.crypto.KeyGenerationParameters; |
| import com.android.org.bouncycastle.crypto.params.DSAKeyGenerationParameters; |
| import com.android.org.bouncycastle.crypto.params.DSAParameters; |
| import com.android.org.bouncycastle.crypto.params.DSAPrivateKeyParameters; |
| import com.android.org.bouncycastle.crypto.params.DSAPublicKeyParameters; |
| import com.android.org.bouncycastle.math.ec.WNafUtil; |
| import com.android.org.bouncycastle.util.BigIntegers; |
| |
| /** |
| * a DSA key pair generator. |
| * |
| * This generates DSA keys in line with the method described |
| * in <i>FIPS 186-3 B.1 FFC Key Pair Generation</i>. |
| * @hide This class is not part of the Android public SDK API |
| */ |
| public class DSAKeyPairGenerator |
| implements AsymmetricCipherKeyPairGenerator |
| { |
| private static final BigInteger ONE = BigInteger.valueOf(1); |
| |
| private DSAKeyGenerationParameters param; |
| |
| public void init( |
| KeyGenerationParameters param) |
| { |
| this.param = (DSAKeyGenerationParameters)param; |
| } |
| |
| public AsymmetricCipherKeyPair generateKeyPair() |
| { |
| DSAParameters dsaParams = param.getParameters(); |
| |
| BigInteger x = generatePrivateKey(dsaParams.getQ(), param.getRandom()); |
| BigInteger y = calculatePublicKey(dsaParams.getP(), dsaParams.getG(), x); |
| |
| return new AsymmetricCipherKeyPair( |
| new DSAPublicKeyParameters(y, dsaParams), |
| new DSAPrivateKeyParameters(x, dsaParams)); |
| } |
| |
| private static BigInteger generatePrivateKey(BigInteger q, SecureRandom random) |
| { |
| // B.1.2 Key Pair Generation by Testing Candidates |
| int minWeight = q.bitLength() >>> 2; |
| for (;;) |
| { |
| // TODO Prefer this method? (change test cases that used fixed random) |
| // B.1.1 Key Pair Generation Using Extra Random Bits |
| // BigInteger x = new BigInteger(q.bitLength() + 64, random).mod(q.subtract(ONE)).add(ONE); |
| |
| BigInteger x = BigIntegers.createRandomInRange(ONE, q.subtract(ONE), random); |
| if (WNafUtil.getNafWeight(x) >= minWeight) |
| { |
| return x; |
| } |
| } |
| } |
| |
| private static BigInteger calculatePublicKey(BigInteger p, BigInteger g, BigInteger x) |
| { |
| return g.modPow(x, p); |
| } |
| } |