Refactor RSA engines

2 files changed, 16 insertions, 28 deletions

diff --git a/crypto/src/crypto/engines/RSABlindedEngine.cs b/crypto/src/crypto/engines/RSABlindedEngine.cs
index 8bb9a4f8c..63b8bbf69 100644
--- a/crypto/src/crypto/engines/RSABlindedEngine.cs
+++ b/crypto/src/crypto/engines/RSABlindedEngine.cs
@@ -41,34 +41,17 @@ namespace Org.BouncyCastle.Crypto.Engines
          */
         public virtual void Init(bool forEncryption, ICipherParameters param)
         {
-            core.Init(forEncryption, param);
-
-            if (param is ParametersWithRandom rParam)
+            SecureRandom providedRandom = null;
+            if (param is ParametersWithRandom withRandom)
             {
-                this.key = (RsaKeyParameters)rParam.Parameters;
-
-                if (key is RsaPrivateCrtKeyParameters)
-                {
-                    this.random = rParam.Random;
-                }
-                else
-                {
-                    this.random = null;
-                }
-            }
-            else
-            {
-                this.key = (RsaKeyParameters)param;
-
-                if (key is RsaPrivateCrtKeyParameters)
-                {
-                    this.random = CryptoServicesRegistrar.GetSecureRandom();
-                }
-                else
-                {
-                    this.random = null;
-                }
+                providedRandom = withRandom.Random;
+                param = withRandom.Parameters;
             }
+
+            core.Init(forEncryption, param);
+
+            this.key = (RsaKeyParameters)param;
+            this.random = InitSecureRandom(needed: key is RsaPrivateCrtKeyParameters, providedRandom);
         }
 
         /**
@@ -114,6 +97,11 @@ namespace Org.BouncyCastle.Crypto.Engines
             return core.ConvertOutput(result);
         }
 
+        protected virtual SecureRandom InitSecureRandom(bool needed, SecureRandom provided)
+        {
+            return needed ? CryptoServicesRegistrar.GetSecureRandom(provided) : null;
+        }
+
         private BigInteger ProcessInput(BigInteger input)
         {
             if (!(key is RsaPrivateCrtKeyParameters crt))
diff --git a/crypto/src/crypto/engines/RSACoreEngine.cs b/crypto/src/crypto/engines/RSACoreEngine.cs
index 7040899f9..dcc8d0101 100644
--- a/crypto/src/crypto/engines/RSACoreEngine.cs
+++ b/crypto/src/crypto/engines/RSACoreEngine.cs
@@ -116,10 +116,10 @@ namespace Org.BouncyCastle.Crypto.Engines
             BigInteger qInv = crt.QInv;
 
             // mP = ((input Mod p) ^ dP)) Mod p
-            BigInteger mP = (input.Remainder(p)).ModPow(dP, p);
+            BigInteger mP = input.Remainder(p).ModPow(dP, p);
 
             // mQ = ((input Mod q) ^ dQ)) Mod q
-            BigInteger mQ = (input.Remainder(q)).ModPow(dQ, q);
+            BigInteger mQ = input.Remainder(q).ModPow(dQ, q);
 
             // h = qInv * (mP - mQ) Mod p
             BigInteger h = mP.Subtract(mQ).Multiply(qInv).Mod(p);