core/src/main/java/org/spongycastle/crypto/prng/SP800SecureRandom.java


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package org.spongycastle.crypto.prng;

import java.security.SecureRandom;

import org.spongycastle.crypto.prng.drbg.SP80090DRBG;

public class SP800SecureRandom
    extends SecureRandom
{
    private final DRBGProvider drbgProvider;
    private final boolean predictionResistant;
    private final SecureRandom randomSource;
    private final EntropySource entropySource;

    private SP80090DRBG drbg;

    SP800SecureRandom(SecureRandom randomSource, EntropySource entropySource, DRBGProvider drbgProvider, boolean predictionResistant)
    {
        this.randomSource = randomSource;
        this.entropySource = entropySource;
        this.drbgProvider = drbgProvider;
        this.predictionResistant = predictionResistant;
    }

    public void setSeed(byte[] seed)
    {
        synchronized (this)
        {
            if (randomSource != null)
            {
                this.randomSource.setSeed(seed);
            }
        }
    }

    public void setSeed(long seed)
    {
        synchronized (this)
        {
            // this will happen when SecureRandom() is created
            if (randomSource != null)
            {
                this.randomSource.setSeed(seed);
            }
        }
    }

    public void nextBytes(byte[] bytes)
    {
        synchronized (this)
        {
            if (drbg == null)
            {
                drbg = drbgProvider.get(entropySource);
            }

            // check if a reseed is required...
            if (drbg.generate(bytes, null, predictionResistant) < 0)
            {
                drbg.reseed(entropySource.getEntropy());
                drbg.generate(bytes, null, predictionResistant);
            }
        }
    }

    public byte[] generateSeed(int numBytes)
    {
        byte[] bytes = new byte[numBytes];

        this.nextBytes(bytes);

        return bytes;
    }
}