MacSameTest.java

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import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

/**
 * @test
 * @bug 8048603
 * @summary Check if doFinal and update operation result in same Mac
 * @author Yu-Ching Valerie Peng, Bill Situ, Alexander Fomin
 * @build Utils
 * @run main MacSameTest
 * @key randomness
 */
public class MacSameTest implements MacTest {

    private static final int MESSAGE_SIZE = 25;
    private static final int OFFSET = 5;
    private static final int KEY_SIZE = 70;

    /**
     * Initialize a message, instantiate a Mac object,
     * initialize the object with a SecretKey,
     * feed the message into the Mac object
     * all at once and get the output MAC as result1.
     * Reset the Mac object, chop the message into three pieces,
     * feed into the Mac object sequentially, and get the output MAC as result2.
     * Finally, compare result1 and result2 and see if they are the same.
     *
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Utils.runTests(new MacSameTest());
    }

    @Override
    public void doTest(String algo) throws NoSuchAlgorithmException,
            NoSuchProviderException, InvalidKeyException {
        Mac mac;
        try {
            mac = Mac.getInstance(algo, "SunJCE");
        } catch (NoSuchAlgorithmException nsae) {
            // depending on Solaris configuration,
            // it can support HMAC or not with Mac
            System.out.println("Expected NoSuchAlgorithmException thrown: "
                    + nsae);
            return;
        }

        byte[] plain = new byte[MESSAGE_SIZE];
        for (int i = 0; i < MESSAGE_SIZE; i++) {
            plain[i] = (byte) (i % 256);
        }

        byte[] tail = new byte[plain.length - OFFSET];
        System.arraycopy(plain, OFFSET, tail, 0, tail.length);

        SecureRandom srdm = new SecureRandom();
        byte[] keyVal = new byte[KEY_SIZE];
        srdm.nextBytes(keyVal);
        SecretKeySpec keySpec = new SecretKeySpec(keyVal, "HMAC");

        mac.init(keySpec);
        byte[] result1 = mac.doFinal(plain);

        mac.reset();
        mac.update(plain[0]);
        mac.update(plain, 1, OFFSET - 1);
        byte[] result2 = mac.doFinal(tail);

        if (!java.util.Arrays.equals(result1, result2)) {
            throw new RuntimeException("result1 and result2 are not the same");
        }
    }

}