decipher method
Implementation
void decipher(Uint32List x) {
// var x8 = x.buffer.asUint8List();
// if (x.offsetInBytes != 0) x8 = x8.sublist(x.offsetInBytes);
final x8 = Uint8List.sublistView(x);
x[0] ^= P[17];
for (var i = 16; i > 0; i -= 2) {
x[1] ^= F(S, x8, 0) ^ P[i];
x[0] ^= F(S, x8, 4) ^ P[i - 1];
}
var t = x[0];
x[0] = x[1] ^ P[0];
x[1] = t;
}