public static uint[] decrypt_key(Sjcl.Cipher.Aes cipher, uint[] a)
{
if (a.Length == 4) return cipher.Decrypt(a);
List<uint> x = new List<uint>();
for (var i = 0; i < a.Length; i += 4) x.AddRange(cipher.Decrypt(new uint[] { a[i], a[i + 1], a[i + 2], a[i + 3] }));
return x.ToArray();
}