Refactoring in RsaCoreEngine

1 files changed, 12 insertions, 21 deletions

diff --git a/crypto/src/crypto/engines/RSACoreEngine.cs b/crypto/src/crypto/engines/RSACoreEngine.cs
index 2af447841..ffa448b3d 100644
--- a/crypto/src/crypto/engines/RSACoreEngine.cs
+++ b/crypto/src/crypto/engines/RSACoreEngine.cs
@@ -118,39 +118,30 @@ namespace Org.BouncyCastle.Crypto.Engines
 		{
             CheckInitialised();
 
-            if (key is RsaPrivateCrtKeyParameters)
+            if (key is RsaPrivateCrtKeyParameters crt)
 			{
 				//
 				// 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;
+				BigInteger p = crt.P;
+				BigInteger q = crt.Q;
+				BigInteger dP = crt.DP;
+				BigInteger dQ = crt.DQ;
+				BigInteger qInv = crt.QInv;
 
 				// mP = ((input Mod p) ^ dP)) Mod p
-				mP = (input.Remainder(p)).ModPow(dP, p);
+				BigInteger mP = (input.Remainder(p)).ModPow(dP, p);
 
-				// mQ = ((input Mod q) ^ dQ)) Mod q
-				mQ = (input.Remainder(q)).ModPow(dQ, q);
+                // mQ = ((input Mod q) ^ dQ)) Mod q
+                BigInteger 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);
+				BigInteger h = mP.Subtract(mQ).Multiply(qInv).Mod(p);
 
-				return m;
+                // m = h * q + mQ
+                return h.Multiply(q).Add(mQ);
 			}
 
 			return input.ModPow(key.Exponent, key.Modulus);