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/**
 * @test
 * @bug 4844847
 * @summary Test the Signature.update(ByteBuffer) method
 * @author Andreas Sterbenz
 * @key randomness
 * @run main ByteBuffers DSA 512
 * @run main ByteBuffers SHA256withDSA 2048
 */

import java.util.*;
import java.nio.*;

import java.security.*;

public class ByteBuffers {

    public static void main(String[] args) throws Exception {
        Provider p = Security.getProvider(
                            System.getProperty("test.provider.name", "SUN"));
        Random random = new Random();
        int n = 10 * 1024;
        byte[] t = new byte[n];
        random.nextBytes(t);

        String kpgAlgorithm = "DSA";
        int keySize = Integer.parseInt(args[1]);
        KeyPairGenerator kpg = KeyPairGenerator.getInstance(kpgAlgorithm, p);
        kpg.initialize(keySize);
        KeyPair kp = kpg.generateKeyPair();

        String signAlgo = args[0];
        Signature sig = Signature.getInstance(signAlgo, p);
        sig.initSign(kp.getPrivate());
        sig.update(t);
        byte[] signature = sig.sign();

        sig.initVerify(kp.getPublic());

        // test 1: ByteBuffer with an accessible backing array
        ByteBuffer b1 = ByteBuffer.allocate(n + 256);
        b1.position(random.nextInt(256));
        b1.limit(b1.position() + n);
        ByteBuffer b2 = b1.slice();
        b2.put(t);
        b2.clear();
        verify(sig, signature, b2, random);

        // test 2: direct ByteBuffer
        ByteBuffer b3 = ByteBuffer.allocateDirect(t.length);
        b3.put(t);
        b3.clear();
        verify(sig, signature, b3, random);

        // test 3: ByteBuffer without an accessible backing array
        b2.clear();
        ByteBuffer b4 = b2.asReadOnlyBuffer();
        verify(sig, signature, b4, random);

        System.out.println("All tests passed");
    }

    private static void verify(Signature sig, byte[] signature, ByteBuffer b, Random random) throws Exception {
        int lim = b.limit();
        b.limit(random.nextInt(lim));
        sig.update(b);
        if (b.hasRemaining()) {
            throw new Exception("Buffer not consumed");
        }
        b.limit(lim);
        sig.update(b);
        if (b.hasRemaining()) {
            throw new Exception("Buffer not consumed");
        }
        if (sig.verify(signature) == false) {
            throw new Exception("Signature did not verify");
        }
    }
}