Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

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

@@ -0,0 +1,33 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace System.IdentityModel.Tokens
+{
+    using System.ComponentModel;
+    using System.Diagnostics;
+    
+    public enum SecurityKeyUsage
+    {
+        Exchange,
+        Signature
+    }
+
+    static class SecurityKeyUsageHelper
+    {
+        internal static bool IsDefined(SecurityKeyUsage value)
+        {
+            return (value == SecurityKeyUsage.Exchange
+                || value == SecurityKeyUsage.Signature);
+        }
+
+        internal static void Validate(SecurityKeyUsage value)
+        {
+            if (!IsDefined(value))
+            {
+                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidEnumArgumentException("value", (int)value,
+                    typeof(SecurityKeyUsage)));
+            }
+        }
+    }
+}