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); }