generateHmacSha512 method
Implementation
String generateHmacSha512(String message, String secretKey) {
var key = utf8.encode(secretKey);
var bytes = utf8.encode(message);
var hmacSha512 = Hmac(sha512, key); // HMAC-SHA512
var digest = hmacSha512.convert(bytes);
return digest.toString();
}