Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/Security/Cryptography/HomogenizingCryptoServiceWrapper.cs

@@ -0,0 +1,58 @@
+//------------------------------------------------------------------------------
+// <copyright file="HomogenizingCryptoServiceWrapper.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Security.Cryptography {
+    using System;
+    using System.Configuration;
+    using System.Security.Cryptography;
+
+    // Wraps an ICryptoService instance and homogenizes any exceptions that might occur.
+
+    internal sealed class HomogenizingCryptoServiceWrapper : ICryptoService {
+
+        public HomogenizingCryptoServiceWrapper(ICryptoService wrapped) {
+            WrappedCryptoService = wrapped;
+        }
+
+        internal ICryptoService WrappedCryptoService {
+            get;
+            private set;
+        }
+
+        private static byte[] HomogenizeErrors(Func<byte[], byte[]> func, byte[] input) {
+            // If the underlying method returns null or throws an exception, the
+            // error will be homogenized as a single CryptographicException.
+
+            byte[] output = null;
+            bool allowExceptionToBubble = false;
+
+            try {
+                output = func(input);
+                return output;
+            }
+            catch (ConfigurationException) {
+                // ConfigurationException isn't a side channel; it means the application is misconfigured.
+                // We need to bubble this up so that the developer can react to it.
+                allowExceptionToBubble = true;
+                throw;
+            }
+            finally {
+                if (output == null && !allowExceptionToBubble) {
+                    throw new CryptographicException();
+                }
+            }
+        }
+
+        public byte[] Protect(byte[] clearData) {
+            return HomogenizeErrors(WrappedCryptoService.Protect, clearData);
+        }
+
+        public byte[] Unprotect(byte[] protectedData) {
+            return HomogenizeErrors(WrappedCryptoService.Unprotect, protectedData);
+        }
+
+    }
+}