super("HMACT64");
        int length = Math.min(key.length, BLOCK_LENGTH);
        for (int i = 0; i < length; i++) {
            ipad[i] = (byte) (key[i] ^ IPAD);
            opad[i] = (byte) (key[i] ^ OPAD);
        }
        for (int i = length; i < BLOCK_LENGTH; i++) {
            ipad[i] = IPAD;
            opad[i] = OPAD;
        }
        try {
            md5 = MessageDigest.getInstance("MD5");

        int length = Math.min(key.length, BLOCK_LENGTH);
        for ( int i = 0; i < length; i++ ) {
            this.ipad[ i ] = (byte) ( key[ i ] ^ IPAD );
            this.opad[ i ] = (byte) ( key[ i ] ^ OPAD );
        }
        for ( int i = length; i < BLOCK_LENGTH; i++ ) {
            this.ipad[ i ] = IPAD;
            this.opad[ i ] = OPAD;
        }

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