export declare const Base64Encoder: {
    _keyStr: string;
    /**
     * Function to encode an arbitrary string
     *
     * @param   string  e   String to be encoded
     * @return  string  t   Encoded string e
     */
    encode: (e: string) => string;
    /**
     * Function to decode a string encoded by Base64Encoder.encode
     *
     * @param   string  e   String to be decoded
     * @return  string  t   Decoded string e
     */
    decode: (e: string) => string;
    /**
     * Function to perfom utf8 encoding on an arbitrary string
     *
     * @param   string  e   String to be utf8 encoded
     * @return  string  t   Encoded string e
     */
    _utf8_encode: (e: string) => string;
    /**
     * Function to decode a string encoded by Base64Encoder._utf8_encode
     *
     * @param   string  e   String to be utf8 decoded
     * @return  string  t   Decoded string e
     */
    _utf8_decode: (e: string) => string;
};