Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.IdentityModel/System/IdentityModel/Tokens/ProofDescriptor.cs

@@ -0,0 +1,32 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace System.IdentityModel.Tokens
+{
+    using System;
+    using RSTR = System.IdentityModel.Protocols.WSTrust.RequestSecurityTokenResponse;
+
+    /// <summary>
+    /// Base class for SymmetricProofDescriptor and AsymmetricProofDescriptor.
+    /// </summary>
+    public abstract class ProofDescriptor
+    {
+        
+        /// <summary>
+        /// Sets the appropriate things, such as requested proof token, inside the RSTR 
+        /// based on what is inside the proof descriptor instance. 
+        /// </summary>
+        /// <param name="response">The RSTR object that this proof descriptor needs to modify.</param>
+        public abstract void ApplyTo(RSTR response);
+
+
+        /// <summary>
+        /// Gets the key identifier that can be used inside issued to define the key
+        /// either symmetric or assymetric. If the key is symmetric, it is usually the binary secret
+        /// or encrypted key; if it is asymmetric it is usually the key identifier from the RST/UseKey
+        /// i.e. the public key.
+        /// </summary>
+        public abstract SecurityKeyIdentifier KeyIdentifier { get; }
+    }
+}