}
        for (int i = length; i < BLOCK_LENGTH; i++) {
            this.ipad[i] = IPAD;
            this.opad[i] = OPAD;
        }

        this.md5 = Crypto.getMD5();
        engineReset();
    }

    private HMACT64(final HMACT64 hmac) throws CloneNotSupportedException {
        super("HMACT64");
        this.ipad = hmac.ipad;
        this.opad = hmac.opad;

        }
        try {
            md5 = MessageDigest.getInstance("MD5");
        } catch (final Exception ex) {
            throw new IllegalStateException(ex.getMessage());
        }
        engineReset();
    }

    private HMACT64(final HMACT64 hmac) throws CloneNotSupportedException {
        super("HMACT64");
        this.ipad = hmac.ipad;
        this.opad = hmac.opad;

    /**
     * Creates a new MD4 message digest instance.
     * Initializes the digest with the MD4 algorithm parameters.
     */
    public MD4() {
        super("MD4");
        engineReset();
    }

    /**
     *    This constructor is here to implement cloneability of this class.
     */
    private MD4(final MD4 md) {
        this();
        context = md.context.clone();