C++ mbedtls md5 hash example

#include <array>
#include <vector>
#include <string>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include "mbedtls/md5.h"
#include "mbedtls/base64.h"

template<std::size_t N>
std::string toHex(const std::array<unsigned char, N>& values);

class Md5Hasher {
private:
    mbedtls_md5_context md5_context;
public:
    Md5Hasher() {
        mbedtls_md5_init(&md5_context);
    }

    void prepare() {
        //Prepare context for hashing byte sequence
        mbedtls_md5_starts_ret(&md5_context);
    }

    void update(std::string input) {
        //Process message a bit
        mbedtls_md5_update_ret(&md5_context, reinterpret_cast<const unsigned char*>(input.c_str()), input.size());
    }

    std::string finish() {
        std::array<unsigned char, 16> outputArr;
        mbedtls_md5_finish_ret(&md5_context, outputArr.data());
        return toHex(outputArr);
    }

    ~Md5Hasher() {
        mbedtls_md5_free(&md5_context);
    }
};


int main() {
    //Collect input
    std::cout << "Input: ";
    std::string input;
    std::getline(std::cin, input);

    Md5Hasher hasher;
    hasher.prepare();
    hasher.update(input);

    std::cout << "MD5 digest is: " << hasher.finish() << "\n";
}
















template<std::size_t N>
std::string toHex(const std::array<unsigned char, N>& values) {
    std::stringstream stream;
    for (int i : values) {
        stream << std::setfill ('0') << std::setw(2)
                << std::hex << i;
    }
  return stream.str();
}

auto oldmain() -> int {

    //Setup context
    mbedtls_md5_context md5_context;

    //Initialize Context
    mbedtls_md5_init(&md5_context);

    //Prepare context for hashing byte sequence
    mbedtls_md5_starts_ret(&md5_context);

    std::cout << "Input: ";
    std::string input;
    std::getline(std::cin, input);

    //Process message a bit
    mbedtls_md5_update_ret(&md5_context, reinterpret_cast<const unsigned char*>(input.c_str()), input.size());

    std::array<unsigned char, 16> outputArr;
    mbedtls_md5_finish_ret(&md5_context, outputArr.data());

    std::string result = toHex(outputArr);

    std::cout << "Md5 of input is " << std::quoted(result) << "\n";

    // Destroy context
    mbedtls_md5_free(&md5_context);
    std::cout << "Hello\n";

    return 0;
}