### Пример реализации генерации подписи для Node.js: 

```js
const crypto = require('crypto');
class XsollaWebhookSignature {
    // IMPORTANT: jsonBody must be the raw JSON string exactly as received from Xsolla
    static computeSha1(jsonBody, secretKey) {
        // Concatenation of the JSON from the request body and the project's secret key
        const dataToSign = jsonBody + secretKey;
        // Create SHA1 hash
        const hash = crypto.createHash('sha1');
        hash.update(dataToSign, 'utf8');
        // Convert to lowercase hexadecimal string
        return hash.digest('hex').toLowerCase();
    }
    static verifySignature(jsonBody, secretKey, receivedSignature) {
        const computedSignature = this.computeSha1(jsonBody, secretKey);
        const cleanReceivedSignature = receivedSignature.toLowerCase();
        // Check if signatures have the same length before using timingSafeEqual
        if (computedSignature.length !== cleanReceivedSignature.length) {
            return false;
        }
        try {
            return crypto.timingSafeEqual(
                Buffer.from(computedSignature, 'hex'),
                Buffer.from(cleanReceivedSignature, 'hex')
            );
        } catch (error) {
            // Return false if there's any error (e.g., invalid hex characters)
            return false;
        }
    }
}
```