C++ビッグデータ開発におけるデータ改ざんにどう対処するか?

#include <iostream>
#include <iomanip>
#include <openssl/sha.h>
#include <string>

std::string calculateChecksum(const std::string& data)
{
    unsigned char hash[SHA256_DIGEST_LENGTH];
    SHA256_CTX sha256;
    SHA256_Init(&sha256);
    SHA256_Update(&sha256, data.c_str(), data.length());
    SHA256_Final(hash, &sha256);

    std::stringstream ss;
    for (int i = 0; i < SHA256_DIGEST_LENGTH; i++)
    {
        ss << std::hex << std::setw(2) << std::setfill('0') << (int)hash[i];
    }

    return ss.str();
}

int main()
{
    std::string data = "Hello, world!";
    std::string checksum = calculateChecksum(data);
    std::cout << "Checksum: " << checksum << std::endl;

    return 0;
}

#include <iostream>
#include <string>
#include <cryptopp/rsa.h>
#include <cryptopp/osrng.h>
#include <cryptopp/base64.h>

std::string generateRSAKey()
{
    CryptoPP::AutoSeededRandomPool rng;
    CryptoPP::RSA::PrivateKey privateKey;
    privateKey.GenerateRandomWithKeySize(rng, 2048);
    CryptoPP::Base64Encoder privateKeyEncoder;

    privateKey.DEREncode(privateKeyEncoder);
    privateKeyEncoder.MessageEnd();
  
    std::string encodedPrivateKey;
    CryptoPP::word64 size = privateKeyEncoder.MaxRetrievable();
    if(size)
    {
        encodedPrivateKey.resize(size);
        privateKeyEncoder.Get((CryptoPP::byte*)&encodedPrivateKey[0], size);
    }

    return encodedPrivateKey;
}

std::string signData(const std::string& privateKey, const std::string& data)
{
    CryptoPP::AutoSeededRandomPool rng;
    CryptoPP::RSA::PrivateKey privateKey;

    std::string privateKeyDecoded;
    CryptoPP::Base64Decoder privateKeyDecoder;
    privateKeyDecoder.Put((CryptoPP::byte*)privateKey.data(), privateKey.size());
    privateKeyDecoder.MessageEnd();

    privateKeyDecoded.resize(privateKeyDecoder.MaxRetrievable());
    privateKeyDecoder.Get((CryptoPP::byte*)&privateKeyDecoded[0], privateKeyDecoded.size());

    privateKey.BERDecode(CryptoPP::StringSource(privateKeyDecoded, true).Ref());

    CryptoPP::RSASSA_PKCS1v15_SHA_Signer signer(privateKey);
    CryptoPP::RSASSA_PKCS1v15_SHA_Signer::Signer signer(rng, signer);

    size_t length = signer.MaxSignatureLength();

    std::string signature;
    signature.resize(length);

    CryptoPP::ArraySink signatureSink((CryptoPP::byte*)&signature[0], length);
    signer.SignMessage(rng, (const CryptoPP::byte*)data.data(), data.size(), signatureSink);

    signature.resize(signatureSink.TotalPutLength());
    return signature;
}

int main()
{
    std::string privateKey = generateRSAKey();
    std::string data = "Hello, world!";
    std::string signature = signData(privateKey, data);

    std::cout << "Signature: " << signature << std::endl;

    return 0;
}