A DESCRIPTION OF THE PROBLEM :
When reinitializing a Signature object with a new SecureRandom via initSign(PrivateKey, SecureRandom), the new random source is not used for subsequent signing operations with DSA/SHA256withDSA algorithms.


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import java.security.*;
import java.util.Arrays;


public class TestInitSignWithMyOwnRandom {

    public static void main(String[] args) throws Exception {
        Provider p = Security.getProvider(
                System.getProperty("test.provider.name", "SUN"));
        String kpgAlgorithm = "DSA";
// args = new String[]{"DSA", "512"};
        args = new String[]{"SHA256withDSA", "2048"};
        int keySize = Integer.parseInt(args[1]);
        KeyPairGenerator kpg = KeyPairGenerator.getInstance(kpgAlgorithm, p);
        kpg.initialize(keySize);
        KeyPair kp = kpg.generateKeyPair();
        TestRandomSource rand = new TestRandomSource();
        TestRandomSource rand2 = new TestRandomSource();
        String signAlgo = args[0];
        byte[] data = new byte[20000];
        Signature sig = Signature.getInstance(signAlgo, p);
        sig.initSign(kp.getPrivate(), rand);
        sig.update(data);
        sig.sign();
        if (!rand.isUsed()) {
            throw new Exception("Custom random source is not used");
        }

        sig.initSign(kp.getPrivate(), rand2);
        for (int i = 0; i < 20000; i++){
            data[i] = (byte) ((System.currentTimeMillis() + i) % 256);
        }
        sig.update(data);
        sig.sign();
        if (!rand2.isUsed()) { // Check if new random is used
            throw new Exception("New random source not used after reinitialization");
        }
    }

}

import java.security.SecureRandom;
class TestRandomSource extends SecureRandom {
    private int count = 0;
    private final SecureRandom delegate = new SecureRandom();

    @Override
    public void nextBytes(byte[] bytes) {
        count++;
        delegate.nextBytes(bytes);
    }

    public boolean isUsed() {
        return count > 0;
    }
}
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