Org.BouncyCastle.Crypto.Modes.GcmBlockCipher.GetMac C# (CSharp) Method

		public virtual byte[] GetMac()
		{
			return Arrays.Clone(macBlock);
		}

		private void randomTest(
			SecureRandom	srng,
			IGcmMultiplier	m)
		{
			int kLength = 16 + 8 * srng.Next(3);
			byte[] K = new byte[kLength];
			srng.NextBytes(K);

			int pLength = srng.Next(1024);
			byte[] P = new byte[pLength];
			srng.NextBytes(P);

			int aLength = srng.Next(1024);
			byte[] A = new byte[aLength];
			srng.NextBytes(A);

			int ivLength = 1 + srng.Next(1024);
			byte[] IV = new byte[ivLength];
			srng.NextBytes(IV);

			GcmBlockCipher cipher = new GcmBlockCipher(new AesFastEngine(), m);
			AeadParameters parameters = new AeadParameters(new KeyParameter(K), 16 * 8, IV, A);
			cipher.Init(true, parameters);
			byte[] C = new byte[cipher.GetOutputSize(P.Length)];
			int len = cipher.ProcessBytes(P, 0, P.Length, C, 0);
			len += cipher.DoFinal(C, len);

			if (C.Length != len)
			{
//				Console.WriteLine("" + C.Length + "/" + len);
				Fail("encryption reported incorrect length in randomised test");
			}

			byte[] encT = cipher.GetMac();
			byte[] tail = new byte[C.Length - P.Length];
			Array.Copy(C, P.Length, tail, 0, tail.Length);

			if (!AreEqual(encT, tail))
			{
				Fail("stream contained wrong mac in randomised test");
			}

			cipher.Init(false, parameters);
			byte[] decP = new byte[cipher.GetOutputSize(C.Length)];
			len = cipher.ProcessBytes(C, 0, C.Length, decP, 0);
			len += cipher.DoFinal(decP, len);

			if (!AreEqual(P, decP))
			{
				Fail("incorrect decrypt in randomised test");
			}

			byte[] decT = cipher.GetMac();
			if (!AreEqual(encT, decT))
			{
				Fail("decryption produced different mac from encryption");
			}
		}