Encryption.cpp

#include "Encryption.h"

void XOR(std::string& data, const std::string& key) {

    for (size_t i = 0; i != data.size(); i++)
        data[i] ^= key[i % key.size()];
}

int AESDecrypt(std::vector<BYTE>& payload, char* key, size_t keylen) {

    HCRYPTPROV hProv;
    HCRYPTHASH hHash;
    HCRYPTKEY hKey;

    if (!CryptAcquireContextW(&hProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)) {
        return -1;
    }
    if (!CryptCreateHash(hProv, CALG_SHA_256, 0, 0, &hHash)) {
        return -1;
    }
    if (!CryptHashData(hHash, (BYTE*)key, (DWORD)keylen, 0)) {
        return -1;
    }
    if (!CryptDeriveKey(hProv, CALG_AES_256, hHash, 0, &hKey)) {
        return -1;
    }
    DWORD dataSize = static_cast<DWORD>(payload.size());
    DWORD* pDataSize = &dataSize;

    if (!CryptDecrypt(hKey, (HCRYPTHASH)NULL, 0, 0, (BYTE*)payload.data(), pDataSize)) {
        return -1;
    }

    CryptReleaseContext(hProv, 0);
    CryptDestroyHash(hHash);
    CryptDestroyKey(hKey);

    return 0;
}