#include <iostream>
#include <sstream>
using namespace std;
class Cipher
{
public:

 static std::string str2HexStr(std::string str)
 {
 const std::string hex = "0123456789ABCDEF";
 std::stringstream ss;
 
 for (std::string::size_type i = 0; i < str.size(); ++i)
 ss << hex[(unsigned char)str[i] >> 4] << hex[(unsigned char)str[i] & 0xf];
 
 return ss.str();
 }

 static std::string hexStr2Str(std::string str)
 {
 std::string result;
 for (size_t i = 0; i < str.length(); i += 2)
 {
 std::string byte = str.substr(i, 2);
 char chr = (char)(int)strtol(byte.c_str(), NULL, 16);
 result.push_back(chr);
 }
 return result;
 }


private:

};


// int main()
// {
// cout << Cipher::str2HexStr("{\"data\":{\"method\":\"t4\",\"param\":[\"helloaa\"],") << endl;
// cout << Cipher::hexStr2Str("7B2264617461223A7B226D6574686F64223A227434222C22706172616D223A5B2268656C6C6F6161225D2C");
// return 0;
// }