### Пример реализации генерации подписи для C++: 

```c++
#include <string>
#include <sstream>
#include <iomanip>
#include <openssl/sha.h>
class XsollaWebhookSignature {
public:
    static std::string computeSha1(const std::string& jsonBody, const std::string& secretKey) {
        // Concatenation of the JSON from the request body and the project's secret key
        std::string dataToSign = jsonBody + secretKey;
        unsigned char digest[SHA_DIGEST_LENGTH];
        // Create SHA1 hash
        SHA1(reinterpret_cast<const unsigned char*>(dataToSign.c_str()),
             dataToSign.length(), digest);
        // Convert to lowercase hexadecimal string
        std::ostringstream hexStream;
        hexStream << std::hex << std::setfill('0');
        for (int i = 0; i < SHA_DIGEST_LENGTH; ++i) {
            hexStream << std::setw(2) << static_cast<unsigned int>(digest[i]);
        }
        return hexStream.str();
    }
    static bool verifySignature(const std::string& jsonBody, const std::string& secretKey, const std::string& receivedSignature) {
        std::string computedSignature = computeSha1(jsonBody, secretKey);
        // Timing-safe comparison
        if (computedSignature.length() != receivedSignature.length()) {
            return false;
        }
        volatile unsigned char result = 0;
        for (size_t i = 0; i < computedSignature.length(); ++i) {
            result |= (computedSignature[i] ^ receivedSignature[i]);
        }
        return result == 0;
    }
};
```