Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.IdentityModel/System/IdentityModel/Protocols/WSTrust/Entropy.cs

@@ -0,0 +1,73 @@
+//-----------------------------------------------------------------------
+// <copyright file="Entropy.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace System.IdentityModel.Protocols.WSTrust
+{
+    using System.IdentityModel.Tokens;
+
+    /// <summary>
+    /// The Entropy used in both token request message and token response message. 
+    /// </summary>
+    public class Entropy : ProtectedKey
+    {
+        /// <summary>
+        /// Use this constructor to create an Entropy object with some randomly generated bytes.
+        /// </summary>
+        /// <param name="entropySizeInBits">The entropySizeInBits of the key material inside the entropy.</param>
+        public Entropy( int entropySizeInBits )
+            : this( CryptoHelper.GenerateRandomBytes( entropySizeInBits ) )
+        {
+        }
+
+        /// <summary>
+        /// Constructor for sending entropy in binary secret format.
+        /// </summary>
+        /// <param name="secret">The key material.</param>
+        public Entropy( byte[] secret )
+            : base( secret )
+        {
+        }
+
+        /// <summary>
+        /// Constructor for sending entropy in encrypted key format.
+        /// </summary>
+        /// <param name="secret">The key material.</param>
+        /// <param name="wrappingCredentials">The encrypting credentials used to encrypt the key material.</param>
+        public Entropy( byte[] secret, EncryptingCredentials wrappingCredentials )
+            : base( secret, wrappingCredentials )
+        {
+        }
+
+        /// <summary>
+        /// Constructs an entropy instance with the protected key.
+        /// </summary>
+        /// <param name="protectedKey">The protected key which can be either binary secret or encrypted key.</param>
+        public Entropy( ProtectedKey protectedKey )
+            : base( GetKeyBytesFromProtectedKey( protectedKey ), GetWrappingCredentialsFromProtectedKey( protectedKey ) )
+        {
+        }
+
+        static byte[] GetKeyBytesFromProtectedKey( ProtectedKey protectedKey )
+        {
+            if ( protectedKey == null )
+            {
+                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull( "protectedKey" );
+            }
+
+            return protectedKey.GetKeyBytes();
+        }
+
+        static EncryptingCredentials GetWrappingCredentialsFromProtectedKey( ProtectedKey protectedKey )
+        {
+            if ( protectedKey == null )
+            {
+                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull( "protectedKey" );
+            }
+
+            return protectedKey.WrappingCredentials;
+        }
+    }
+}