Org.BouncyCastle.Crypto.Engines.IesEngine.EncryptBlock C# (CSharp) Метод

        private byte[] EncryptBlock(
            byte[]  input,
            int     inOff,
            int     inLen,
            byte[]  z)
        {
            byte[]          C = null;
            KeyParameter    macKey = null;
            KdfParameters   kParam = new KdfParameters(z, param.GetDerivationV());
            int             c_text_length = 0;
            int             macKeySize = param.MacKeySize;

            if (cipher == null)     // stream mode
            {
                byte[] Buffer = GenerateKdfBytes(kParam, inLen + (macKeySize / 8));

                C = new byte[inLen + mac.GetMacSize()];
                c_text_length = inLen;

                for (int i = 0; i != inLen; i++)
                {
                    C[i] = (byte)(input[inOff + i] ^ Buffer[i]);
                }

                macKey = new KeyParameter(Buffer, inLen, (macKeySize / 8));
            }
            else
            {
                int cipherKeySize = ((IesWithCipherParameters)param).CipherKeySize;
                byte[] Buffer = GenerateKdfBytes(kParam, (cipherKeySize / 8) + (macKeySize / 8));

                cipher.Init(true, new KeyParameter(Buffer, 0, (cipherKeySize / 8)));

                c_text_length = cipher.GetOutputSize(inLen);
                byte[] tmp = new byte[c_text_length];

                int len = cipher.ProcessBytes(input, inOff, inLen, tmp, 0);
                len += cipher.DoFinal(tmp, len);

                C = new byte[len + mac.GetMacSize()];
                c_text_length = len;

                Array.Copy(tmp, 0, C, 0, len);

                macKey = new KeyParameter(Buffer, (cipherKeySize / 8), (macKeySize / 8));
            }

            byte[] macIV = param.GetEncodingV();

            mac.Init(macKey);
            mac.BlockUpdate(C, 0, c_text_length);
            mac.BlockUpdate(macIV, 0, macIV.Length);
            //
            // return the message and it's MAC
            //
            mac.DoFinal(C, c_text_length);
            return C;
        }