Cryptopp BCD与字符互转

std::string fromHex(const std::string &from) {
    std::string to;
    CryptoPP::StringSource hexStringSource(from, true,
                                           new CryptoPP::HexDecoder(new CryptoPP::StringSink(to))); 

    return to;
}

std::string toHex(const std::string &from) {
    std::string to;
    CryptoPP::StringSource hexStringSource(from, true,
                                           new CryptoPP::HexEncoder(new CryptoPP::StringSink(to))); 

    return to;
}