calcNonce function
Calculate a random number for nonce
Implementation
int calcNonce() {
final random = Random.secure();
int length = 8;
String chars = '0123456789ABCDEF';
String hex = '';
while (length-- > 0) {
hex += chars[(random.nextInt(16)) | 0];
}
return int.parse(hex, radix: 16);
}