calculateX static method
Implementation
static BigInt calculateX(Digest digest, BigInt N, Uint8List salt,
Uint8List identity, Uint8List password) {
var output = Uint8List(digest.digestSize);
digest.update(identity, 0, identity.length);
digest.updateByte(':'.codeUnitAt(0));
digest.update(password, 0, password.length);
digest.doFinal(output, 0);
digest.update(salt, 0, salt.length);
digest.update(output, 0, output.length);
digest.doFinal(output, 0);
return decodeBigInt(output);
}