BraintreeEncryption.Library.BouncyCastle.Crypto.Engines.RsaCoreEngine.ProcessBlock C# (CSharp) Method

        public BigInteger ProcessBlock(
			BigInteger input)
        {
            if (key is RsaPrivateCrtKeyParameters)
            {
                //
                // we have the extra factors, use the Chinese Remainder Theorem - the author
                // wishes to express his thanks to Dirk Bonekaemper at rtsffm.com for
                // advice regarding the expression of this.
                //
                RsaPrivateCrtKeyParameters crtKey = (RsaPrivateCrtKeyParameters)key;

                BigInteger p = crtKey.P;;
                BigInteger q = crtKey.Q;
                BigInteger dP = crtKey.DP;
                BigInteger dQ = crtKey.DQ;
                BigInteger qInv = crtKey.QInv;

                BigInteger mP, mQ, h, m;

                // mP = ((input Mod p) ^ dP)) Mod p
                mP = (input.Remainder(p)).ModPow(dP, p);

                // mQ = ((input Mod q) ^ dQ)) Mod q
                mQ = (input.Remainder(q)).ModPow(dQ, q);

                // h = qInv * (mP - mQ) Mod p
                h = mP.Subtract(mQ);
                h = h.Multiply(qInv);
                h = h.Mod(p);               // Mod (in Java) returns the positive residual

                // m = h * q + mQ
                m = h.Multiply(q);
                m = m.Add(mQ);

                return m;
            }

            return input.ModPow(key.Exponent, key.Modulus);
        }

        /**
         * Process a single block using the basic RSA algorithm.
         *
         * @param inBuf the input array.
         * @param inOff the offset into the input buffer where the data starts.
         * @param inLen the length of the data to be processed.
         * @return the result of the RSA process.
         * @exception DataLengthException the input block is too large.
         */
        public byte[] ProcessBlock(
            byte[]      inBuf,
            int inOff,
            int inLen)
        {
            if (core == null)
            {
                throw new InvalidOperationException("RSA engine not initialised");
            }

            return(core.ConvertOutput(core.ProcessBlock(core.ConvertInput(inBuf, inOff, inLen))));
        }