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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8 with debug enabled.

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package org.bouncycastle.crypto.prng;

import java.security.SecureRandom;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.util.Pack;

public class X931SecureRandomBuilder
{
    private SecureRandom random;          // JDK 1.1 complains on final.
    private EntropySourceProvider entropySourceProvider;

    private byte[] dateTimeVector;

    /**
     * Basic constructor, creates a builder using an EntropySourceProvider based on the default SecureRandom with
     * predictionResistant set to false.
     * 

* Any SecureRandom created from a builder constructed like this will make use of input passed to SecureRandom.setSeed() if * the default SecureRandom does for its generateSeed() call. *

*/ public X931SecureRandomBuilder() { this(new SecureRandom(), false); } /** * Construct a builder with an EntropySourceProvider based on the passed in SecureRandom and the passed in value * for prediction resistance. *

* Any SecureRandom created from a builder constructed like this will make use of input passed to SecureRandom.setSeed() if * the passed in SecureRandom does for its generateSeed() call. *

* @param entropySource * @param predictionResistant */ public X931SecureRandomBuilder(SecureRandom entropySource, boolean predictionResistant) { this.random = entropySource; this.entropySourceProvider = new BasicEntropySourceProvider(random, predictionResistant); } /** * Create a builder which makes creates the SecureRandom objects from a specified entropy source provider. *

* Note: If this constructor is used any calls to setSeed() in the resulting SecureRandom will be ignored. *

* @param entropySourceProvider a provider of EntropySource objects. */ public X931SecureRandomBuilder(EntropySourceProvider entropySourceProvider) { this.random = null; this.entropySourceProvider = entropySourceProvider; } public X931SecureRandomBuilder setDateTimeVector(byte[] dateTimeVector) { this.dateTimeVector = dateTimeVector; return this; } /** * Construct a X9.31 secure random generator using the passed in engine and key. If predictionResistant is true the * generator will be reseeded on each request. * * @param engine a block cipher to use as the operator. * @param key the block cipher key to initialise engine with. * @param predictionResistant true if engine to be reseeded on each use, false otherwise. * @return a SecureRandom. */ public X931SecureRandom build(BlockCipher engine, KeyParameter key, boolean predictionResistant) { if (dateTimeVector == null) { dateTimeVector = new byte[engine.getBlockSize()]; Pack.longToBigEndian(System.currentTimeMillis(), dateTimeVector, 0); } engine.init(true, key); return new X931SecureRandom(random, new X931RNG(engine, dateTimeVector, entropySourceProvider.get(engine.getBlockSize() * 8)), predictionResistant); } }




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