Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Web/Configuration/MachineKeyCompatibilityMode.cs

@@ -0,0 +1,25 @@
+//------------------------------------------------------------------------------
+// <copyright file="MachineKeyCompatibilityMode.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Web.Configuration {
+    using System;
+
+    public enum MachineKeyCompatibilityMode {
+
+        // 2.0 SP1 mode encryption doesn't use IVs when encrypting data and is included only for legacy reasons.
+        Framework20SP1 = 0,
+
+        // 2.0 SP2 mode encryption uses IVs when encrypting data.
+        // See: DevDiv Bugs #137864 (http://bugcheck/bugs/DevDivBugs/137864)
+        Framework20SP2 = 1,
+
+        // 4.5 mode encryption uses IVs, signing, and a purpose (subkey derivation) to encrypt data.
+        // See: DevDiv #48244 (http://vstfdevdiv:8080/DevDiv2/web/wi.aspx?id=48244), which the overall Crypto DCR is a reaction to
+        // See: DevDiv #87406 (http://vstfdevdiv:8080/DevDiv2/web/wi.aspx?id=87406)
+        Framework45 = 2,
+
+    }
+}