int bufferNdx = (int) (count % BLOCK_LENGTH);
        count += len; // update number of bytes
        final int partLen = BLOCK_LENGTH - bufferNdx;
        int i = 0;
        if (len >= partLen) {
            System.arraycopy(input, offset, buffer, bufferNdx, partLen);

            transform(buffer, 0);

            for (i = partLen; i + BLOCK_LENGTH - 1 < len; i += BLOCK_LENGTH) {

public class HMACT64 extends MessageDigest implements Cloneable {

    private static final int BLOCK_LENGTH = 64;

    private static final byte IPAD = (byte) 0x36;

    private static final byte OPAD = (byte) 0x5c;

    private MessageDigest md5;

    private byte[] ipad = new byte[BLOCK_LENGTH];

    private byte[] opad = new byte[BLOCK_LENGTH];

    /**
     * Creates an HMACT64 instance which uses the given secret key material.

class HMACT64 extends MessageDigest implements Cloneable {

    private static final int BLOCK_LENGTH = 64;

    private static final byte IPAD = (byte) 0x36;

    private static final byte OPAD = (byte) 0x5c;

    private final MessageDigest md5;

    private byte[] ipad = new byte[BLOCK_LENGTH];

    private byte[] opad = new byte[BLOCK_LENGTH];

    /**
     * Creates an HMACT64 instance which uses the given secret key material.

        }
    }

    @Test
    void testConstructorWithLongKey() throws NoSuchAlgorithmException {
        // Test constructor with a key longer than BLOCK_LENGTH (64 bytes)
        try (MockedStatic<Crypto> mockedCrypto = mockStatic(Crypto.class)) {
            mockedCrypto.when(Crypto::getMD5).thenReturn(mockMd5);
            HMACT64 hmac = new HMACT64(LONG_TEST_KEY);

    void testConstructorWithLongKey() {
        // Test constructor with a key longer than BLOCK_LENGTH (64 bytes)
        // HMACT64 truncates keys at 64 bytes
        HMACT64 hmac = new HMACT64(LONG_TEST_KEY);
        assertNotNull(hmac);
    }

    @Test
    void testConstructorWithShortKey() {
        // Test constructor with a key shorter than BLOCK_LENGTH (64 bytes)
        HMACT64 hmac = new HMACT64(SHORT_TEST_KEY);