Added OpenID association request and response messages.

More work to do on these messages, but it's a step in the right direction.

14 files changed, 760 insertions, 0 deletions

diff --git a/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj b/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
index ae8525c..b89a22d 100644
--- a/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
+++ b/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
@@ -92,6 +92,7 @@
     <Compile Include="OAuth\ConsumerDescription.cs" />
     <Compile Include="OAuth\ProtocolTests.cs" />
     <Compile Include="OAuth\ServiceProviderDescriptionTests.cs" />
+    <Compile Include="OpenId\Messages\AssociateRequestTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Messaging\ResponseTests.cs" />
     <Compile Include="Scenarios\AppendixScenarios.cs" />
diff --git a/src/DotNetOpenAuth.Test/OpenId/Messages/AssociateRequestTests.cs b/src/DotNetOpenAuth.Test/OpenId/Messages/AssociateRequestTests.cs
new file mode 100644
index 0000000..ff611a1
--- /dev/null
+++ b/src/DotNetOpenAuth.Test/OpenId/Messages/AssociateRequestTests.cs
@@ -0,0 +1,63 @@
+//-----------------------------------------------------------------------
+// <copyright file="AssociateRequestTests.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.Test.OpenId.Messages {
+	using System;
+	using DotNetOpenAuth.Messaging;
+	using DotNetOpenAuth.Messaging.Reflection;
+	using DotNetOpenAuth.OpenId;
+	using DotNetOpenAuth.OpenId.Messages;
+	using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+	[TestClass]
+	public class AssociateRequestTests {
+		private Uri secureRecipient = new Uri("https://hi");
+		private Uri insecureRecipient = new Uri("http://hi");
+		private AssociateRequest request;
+
+		[TestInitialize]
+		public void Setup() {
+			this.request = new AssociateRequest(this.secureRecipient);
+		}
+
+		[TestMethod]
+		public void ConstructorTest() {
+			Assert.AreEqual(this.secureRecipient, this.request.Recipient);
+		}
+
+		[TestMethod]
+		public void MessagePartsTest() {
+			this.request.AssociationType = "HMAC-SHA1";
+			this.request.SessionType = "no-encryption";
+
+			Assert.AreEqual("associate", this.request.Mode);
+			Assert.AreEqual("HMAC-SHA1", this.request.AssociationType);
+			Assert.AreEqual("no-encryption", this.request.SessionType);
+
+			var dict = new MessageDictionary(this.request);
+			Assert.AreEqual(Protocol.OpenId2Namespace, dict["openid.ns"]);
+			Assert.AreEqual("associate", dict["openid.mode"]);
+			Assert.AreEqual("HMAC-SHA1", dict["openid.assoc_type"]);
+			Assert.AreEqual("no-encryption", dict["openid.session_type"]);
+		}
+
+		[TestMethod]
+		public void ValidMessageTest() {
+			this.request = new AssociateRequest(this.secureRecipient);
+			this.request.AssociationType = "HMAC-SHA1";
+			this.request.SessionType = "no-encryption";
+			this.request.EnsureValidMessage();
+		}
+
+		[TestMethod, ExpectedException(typeof(ProtocolException))]
+		public void InvalidMessageTest() {
+			this.request = new AssociateRequest(this.insecureRecipient);
+			this.request.AssociationType = "HMAC-SHA1";
+			this.request.SessionType = "no-encryption";
+			this.request.EnsureValidMessage(); // no-encryption only allowed for secure channels.
+		}
+	}
+}
diff --git a/src/DotNetOpenAuth/DotNetOpenAuth.csproj b/src/DotNetOpenAuth/DotNetOpenAuth.csproj
index 1df143c..40e265d 100644
--- a/src/DotNetOpenAuth/DotNetOpenAuth.csproj
+++ b/src/DotNetOpenAuth/DotNetOpenAuth.csproj
@@ -144,6 +144,20 @@
     <Compile Include="Messaging\MessageTransport.cs" />
     <Compile Include="OAuth\ChannelElements\OAuthServiceProviderMessageTypeProvider.cs" />
     <Compile Include="Messaging\ProtocolException.cs" />
+    <Compile Include="OpenId\Messages\AssociateDiffieHellmanRequest.cs" />
+    <Compile Include="OpenId\Messages\AssociateDiffieHellmanResponse.cs" />
+    <Compile Include="OpenId\Messages\AssociateRequest.cs" />
+    <Compile Include="OpenId\Messages\AssociateSuccessfulResponse.cs" />
+    <Compile Include="OpenId\Messages\AssociateUnencryptedResponse.cs" />
+    <Compile Include="OpenId\Messages\AssociateUnsuccessfulResponse.cs" />
+    <Compile Include="OpenId\Messages\RequestBase.cs" />
+    <Compile Include="OpenId\Messages\ResponseBase.cs" />
+    <Compile Include="OpenId\OpenIdStrings.Designer.cs">
+      <DependentUpon>OpenIdStrings.resx</DependentUpon>
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+    </Compile>
+    <Compile Include="OpenId\Protocol.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="OAuth\Messages\UnauthorizedTokenRequest.cs" />
     <Compile Include="OAuth\ChannelElements\RsaSha1SigningBindingElement.cs" />
@@ -175,6 +189,10 @@
       <Generator>ResXFileCodeGenerator</Generator>
       <LastGenOutput>OAuthStrings.Designer.cs</LastGenOutput>
     </EmbeddedResource>
+    <EmbeddedResource Include="OpenId\OpenIdStrings.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>OpenIdStrings.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
     <EmbeddedResource Include="Strings.resx">
       <Generator>ResXFileCodeGenerator</Generator>
       <LastGenOutput>Strings.Designer.cs</LastGenOutput>
diff --git a/src/DotNetOpenAuth/OpenId/Messages/AssociateDiffieHellmanRequest.cs b/src/DotNetOpenAuth/OpenId/Messages/AssociateDiffieHellmanRequest.cs
new file mode 100644
index 0000000..474e9a7
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Messages/AssociateDiffieHellmanRequest.cs
@@ -0,0 +1,45 @@
+//-----------------------------------------------------------------------
+// <copyright file="AssociateDiffieHellmanRequest.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.Messages {
+	using System;
+	using System.Collections.Generic;
+	using System.Linq;
+	using System.Text;
+	using DotNetOpenAuth.Messaging;
+	using DotNetOpenAuth.Messaging.Reflection;
+
+	/// <summary>
+	/// An OpenID direct request from Relying Party to Provider to initiate an association that uses Diffie-Hellman encryption.
+	/// </summary>
+	internal class AssociateDiffieHellmanRequest : AssociateRequest {
+		/// <summary>
+		/// Initializes a new instance of the <see cref="AssociateDiffieHellmanRequest"/> class.
+		/// </summary>
+		/// <param name="providerEndpoint">The OpenID Provider endpoint.</param>
+		internal AssociateDiffieHellmanRequest(Uri providerEndpoint)
+			: base(providerEndpoint) {
+		}
+
+		/// <summary>
+		/// Gets or sets the openid.dh_modulus value.
+		/// </summary>
+		[MessagePart("openid.dh_modulus", IsRequired = false, AllowEmpty = false)]
+		internal byte[] DiffieHellmanModulus { get; set; }
+
+		/// <summary>
+		/// Gets or sets the openid.dh_gen value.
+		/// </summary>
+		[MessagePart("openid.dh_gen", IsRequired = false, AllowEmpty = false)]
+		internal byte[] DiffieHellmanGen { get; set; }
+
+		/// <summary>
+		/// Gets or sets the openid.dh_consumer_public value.
+		/// </summary>
+		[MessagePart("openid.dh_consumer_public", IsRequired = true, AllowEmpty = false)]
+		internal byte[] DiffieHellmanConsumerPublic { get; set; }
+	}
+}
diff --git a/src/DotNetOpenAuth/OpenId/Messages/AssociateDiffieHellmanResponse.cs b/src/DotNetOpenAuth/OpenId/Messages/AssociateDiffieHellmanResponse.cs
new file mode 100644
index 0000000..666d170
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Messages/AssociateDiffieHellmanResponse.cs
@@ -0,0 +1,32 @@
+//-----------------------------------------------------------------------
+// <copyright file="AssociateDiffieHellmanResponse.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.Messages {
+	using DotNetOpenAuth.Messaging;
+	using DotNetOpenAuth.Messaging.Reflection;
+
+	/// <summary>
+	/// The successful Diffie-Hellman association response message.
+	/// </summary>
+	/// <remarks>
+	/// Association response messages are described in OpenID 2.0 section 8.2.  This type covers section 8.2.3.
+	/// </remarks>
+	internal class AssociateDiffieHellmanResponse : AssociateSuccessfulResponse {
+		/// <summary>
+		/// Gets or sets the OP's Diffie-Hellman public key. 
+		/// </summary>
+		/// <value>btwoc(g ^ xb mod p)</value>
+		[MessagePart("dh_server_public", IsRequired = true, AllowEmpty = false)]
+		internal byte[] ServerPublic { get; set; }
+
+		/// <summary>
+		/// Gets or sets the MAC key (shared secret), encrypted with the secret Diffie-Hellman value. H is either "SHA1" or "SHA256" depending on the session type. 
+		/// </summary>
+		/// <value>H(btwoc(g ^ (xa * xb) mod p)) XOR MAC key</value>
+		[MessagePart("enc_mac_key", IsRequired = true, AllowEmpty = false)]
+		internal byte[] EncodedMacKey { get; set; }
+	}
+}
diff --git a/src/DotNetOpenAuth/OpenId/Messages/AssociateRequest.cs b/src/DotNetOpenAuth/OpenId/Messages/AssociateRequest.cs
new file mode 100644
index 0000000..0a684ed
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Messages/AssociateRequest.cs
@@ -0,0 +1,62 @@
+//-----------------------------------------------------------------------
+// <copyright file="AssociateRequest.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.Messages {
+	using System;
+	using System.Collections.Generic;
+	using System.Linq;
+	using System.Text;
+	using DotNetOpenAuth.Messaging;
+
+	/// <summary>
+	/// An OpenID direct request from Relying Party to Provider to initiate an association.
+	/// </summary>
+	internal class AssociateRequest : RequestBase {
+		/// <summary>
+		/// Initializes a new instance of the <see cref="AssociateRequest"/> class.
+		/// </summary>
+		/// <param name="providerEndpoint">The OpenID Provider endpoint.</param>
+		internal AssociateRequest(Uri providerEndpoint)
+			: base(providerEndpoint, "associate") {
+		}
+
+		/// <summary>
+		/// Gets or sets the preferred association type. The association type defines the algorithm to be used to sign subsequent messages. 
+		/// </summary>
+		/// <value>Value: A valid association type from Section 8.3.</value>
+		[MessagePart("openid.assoc_type", IsRequired = true, AllowEmpty = false)]
+		internal string AssociationType { get; set; }
+
+		/// <summary>
+		/// Gets or sets the preferred association session type. This defines the method used to encrypt the association's MAC key in transit. 
+		/// </summary>
+		/// <value>Value: A valid association session type from Section 8.4 (Association Session Types). </value>
+		/// <remarks>Note: Unless using transport layer encryption, "no-encryption" MUST NOT be used. </remarks>
+		[MessagePart("openid.session_type", IsRequired = true, AllowEmpty = false)]
+		internal string SessionType { get; set; }
+
+		/// <summary>
+		/// Checks the message state for conformity to the protocol specification
+		/// and throws an exception if the message is invalid.
+		/// </summary>
+		/// <remarks>
+		/// 	<para>Some messages have required fields, or combinations of fields that must relate to each other
+		/// in specialized ways.  After deserializing a message, this method checks the state of the
+		/// message to see if it conforms to the protocol.</para>
+		/// 	<para>Note that this property should <i>not</i> check signatures or perform any state checks
+		/// outside this scope of this particular message.</para>
+		/// </remarks>
+		/// <exception cref="ProtocolException">Thrown if the message is invalid.</exception>
+		public override void EnsureValidMessage() {
+			base.EnsureValidMessage();
+
+			ErrorUtilities.Verify(
+				this.SessionType != "no-encryption" || this.Recipient.IsTransportSecure(),
+				OpenIdStrings.NoEncryptionSessionRequiresHttps,
+				this);
+		}
+	}
+}
diff --git a/src/DotNetOpenAuth/OpenId/Messages/AssociateSuccessfulResponse.cs b/src/DotNetOpenAuth/OpenId/Messages/AssociateSuccessfulResponse.cs
new file mode 100644
index 0000000..523fedd
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Messages/AssociateSuccessfulResponse.cs
@@ -0,0 +1,52 @@
+//-----------------------------------------------------------------------
+// <copyright file="AssociateSuccessfulResponse.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.Messages {
+	using System;
+	using System.Collections.Generic;
+	using System.Linq;
+	using System.Text;
+	using DotNetOpenAuth.Messaging;
+
+	/// <summary>
+	/// The base class that all successful association response messages derive from.
+	/// </summary>
+	/// <remarks>
+	/// Association response messages are described in OpenID 2.0 section 8.2.  This type covers section 8.2.1.
+	/// </remarks>
+	internal abstract class AssociateSuccessfulResponse : ResponseBase {
+		/// <summary>
+		/// Gets or sets the association handle is used as a key to refer to this association in subsequent messages. 
+		/// </summary>
+		/// <value>A string 255 characters or less in length. It MUST consist only of ASCII characters in the range 33-126 inclusive (printable non-whitespace characters). </value>
+		[MessagePart("assoc_handle", IsRequired = true, AllowEmpty = false)]
+		internal string AssociationHandle { get; set; }
+
+		/// <summary>
+		/// Gets or sets the preferred association type. The association type defines the algorithm to be used to sign subsequent messages. 
+		/// </summary>
+		/// <value>Value: A valid association type from Section 8.3.</value>
+		[MessagePart("assoc_type", IsRequired = true, AllowEmpty = false)]
+		internal string AssociationType { get; set; }
+
+		/// <summary>
+		/// Gets or sets the value of the "openid.session_type" parameter from the request. 
+		/// If the OP is unwilling or unable to support this association type, it MUST return an 
+		/// unsuccessful response (Unsuccessful Response Parameters). 
+		/// </summary>
+		/// <value>Value: A valid association session type from Section 8.4 (Association Session Types). </value>
+		/// <remarks>Note: Unless using transport layer encryption, "no-encryption" MUST NOT be used. </remarks>
+		[MessagePart("session_type", IsRequired = true, AllowEmpty = false)]
+		internal string SessionType { get; set; }
+
+		/// <summary>
+		/// Gets or sets the lifetime, in seconds, of this association. The Relying Party MUST NOT use the association after this time has passed. 
+		/// </summary>
+		/// <value>An integer, represented in base 10 ASCII. </value>
+		[MessagePart("expires_in", IsRequired = true)]
+		internal long ExpiresIn { get; set; }
+	}
+}
diff --git a/src/DotNetOpenAuth/OpenId/Messages/AssociateUnencryptedResponse.cs b/src/DotNetOpenAuth/OpenId/Messages/AssociateUnencryptedResponse.cs
new file mode 100644
index 0000000..db365a6
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Messages/AssociateUnencryptedResponse.cs
@@ -0,0 +1,24 @@
+//-----------------------------------------------------------------------
+// <copyright file="AssociateUnencryptedResponse.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.Messages {
+	using DotNetOpenAuth.Messaging;
+	using DotNetOpenAuth.Messaging.Reflection;
+
+	/// <summary>
+	/// The successful unencrypted association response message.
+	/// </summary>
+	/// <remarks>
+	/// Association response messages are described in OpenID 2.0 section 8.2.  This type covers section 8.2.2.
+	/// </remarks>
+	internal class AssociateUnencryptedResponse : AssociateSuccessfulResponse {
+		/// <summary>
+		/// Gets or sets the MAC key (shared secret) for this association, Base 64 (Josefsson, S., “The Base16, Base32, and Base64 Data Encodings,” .) [RFC3548] encoded. 
+		/// </summary>
+		[MessagePart("mac_key", IsRequired = true, AllowEmpty = false)]
+		internal byte[] MacKey { get; set; }
+	}
+}
diff --git a/src/DotNetOpenAuth/OpenId/Messages/AssociateUnsuccessfulResponse.cs b/src/DotNetOpenAuth/OpenId/Messages/AssociateUnsuccessfulResponse.cs
new file mode 100644
index 0000000..4d8bfec
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Messages/AssociateUnsuccessfulResponse.cs
@@ -0,0 +1,48 @@
+//-----------------------------------------------------------------------
+// <copyright file="AssociateUnsuccessfulResponse.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.Messages {
+	using System;
+	using System.Collections.Generic;
+	using System.Linq;
+	using System.Text;
+	using DotNetOpenAuth.Messaging;
+
+	/// <summary>
+	/// The Provider's response to a Relying Party that requested an association that the Provider does not support.
+	/// </summary>
+	/// <remarks>
+	/// This message type described in OpenID 2.0 section 8.2.4.
+	/// </remarks>
+	internal class AssociateUnsuccessfulResponse : ResponseBase {
+		/// <summary>
+		/// A hard-coded string indicating an error occurred.
+		/// </summary>
+		/// <value>"unsupported-type" </value>
+		[MessagePart("error_code", IsRequired = true, AllowEmpty = false)]
+#pragma warning disable 0414 // read by reflection
+		private readonly string Error = "unsupported-type";
+#pragma warning restore 0414
+
+		/// <summary>
+		/// Gets or sets a human-readable message indicating why the association request failed. 
+		/// </summary>
+		[MessagePart("error", IsRequired = true, AllowEmpty = true)]
+		internal string ErrorMessage { get; set; }
+
+		/// <summary>
+		/// Gets or sets an association type supported by the OP from Section 8.3 (Association Types). 
+		/// </summary>
+		[MessagePart("assoc_type", IsRequired = false, AllowEmpty = false)]
+		internal string AssociationType { get; set; }
+
+		/// <summary>
+		/// Gets or sets a valid association session type from Section 8.4 (Association Session Types) that the OP supports. 
+		/// </summary>
+		[MessagePart("session_type", IsRequired = false, AllowEmpty = false)]
+		internal string SessionType { get; set; }
+	}
+}
diff --git a/src/DotNetOpenAuth/OpenId/Messages/RequestBase.cs b/src/DotNetOpenAuth/OpenId/Messages/RequestBase.cs
new file mode 100644
index 0000000..d9b754c
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Messages/RequestBase.cs
@@ -0,0 +1,115 @@
+//-----------------------------------------------------------------------
+// <copyright file="RequestBase.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.Messages {
+	using System;
+	using System.Collections.Generic;
+	using DotNetOpenAuth.Messaging;
+
+	/// <summary>
+	/// A common base class for OpenID request messages.
+	/// </summary>
+	internal class RequestBase : IDirectedProtocolMessage {
+		/// <summary>
+		/// The openid.ns parameter in the message.
+		/// </summary>
+		/// <value>"http://specs.openid.net/auth/2.0" </value>
+		/// <remarks>
+		/// This particular value MUST be present for the request to be a valid OpenID Authentication 2.0 request. Future versions of the specification may define different values in order to allow message recipients to properly interpret the request. 
+		/// </remarks>
+		[MessagePart("openid.ns", IsRequired = true, AllowEmpty = false)]
+#pragma warning disable 0414 // read by reflection
+		private readonly string OpenIdNamespace = Protocol.OpenId2Namespace;
+#pragma warning restore 0414
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="RequestBase"/> class.
+		/// </summary>
+		/// <param name="providerEndpoint">The OpenID Provider endpoint.</param>
+		/// <param name="mode">The value for the openid.mode parameter.</param>
+		protected RequestBase(Uri providerEndpoint, string mode) {
+			if (providerEndpoint == null) {
+				throw new ArgumentNullException("providerEndpoint");
+			}
+			if (String.IsNullOrEmpty(mode)) {
+				throw new ArgumentNullException("mode");
+			}
+
+			this.Recipient = providerEndpoint;
+			this.Mode = mode;
+		}
+
+		/// <summary>
+		/// Gets the value of the openid.mode parameter.
+		/// </summary>
+		[MessagePart("openid.mode", IsRequired = true, AllowEmpty = false)]
+		public string Mode { get; private set; }
+
+		#region IDirectedProtocolMessage Members
+
+		/// <summary>
+		/// Gets the recipient of the message.
+		/// </summary>
+		/// <value>The OP endpoint, or the RP return_to.</value>
+		public Uri Recipient {
+			get;
+			private set;
+		}
+
+		#endregion
+
+		#region IProtocolMessage Members
+
+		/// <summary>
+		/// Gets the version of the protocol this message is prepared to implement.
+		/// </summary>
+		/// <value>Version 2.0</value>
+		public Version ProtocolVersion {
+			get { return new Version(2, 0); }
+		}
+
+		/// <summary>
+		/// Gets the level of protection this message requires.
+		/// </summary>
+		/// <value><see cref="MessageProtections.None"/></value>
+		public MessageProtections RequiredProtection {
+			get { return MessageProtections.None; }
+		}
+
+		/// <summary>
+		/// Gets a value indicating whether this is a direct or indirect message.
+		/// </summary>
+		/// <value><see cref="MessageTransport.Direct"/></value>
+		public MessageTransport Transport {
+			get { return MessageTransport.Direct; }
+		}
+
+		/// <summary>
+		/// Gets the extra, non-OAuth parameters included in the message.
+		/// </summary>
+		/// <value>An empty dictionary.</value>
+		public IDictionary<string, string> ExtraData {
+			get { return EmptyDictionary<string, string>.Instance; }
+		}
+
+		/// <summary>
+		/// Checks the message state for conformity to the protocol specification
+		/// and throws an exception if the message is invalid.
+		/// </summary>
+		/// <remarks>
+		/// 	<para>Some messages have required fields, or combinations of fields that must relate to each other
+		/// in specialized ways.  After deserializing a message, this method checks the state of the
+		/// message to see if it conforms to the protocol.</para>
+		/// 	<para>Note that this property should <i>not</i> check signatures or perform any state checks
+		/// outside this scope of this particular message.</para>
+		/// </remarks>
+		/// <exception cref="ProtocolException">Thrown if the message is invalid.</exception>
+		public virtual void EnsureValidMessage() {
+		}
+
+		#endregion
+	}
+}
diff --git a/src/DotNetOpenAuth/OpenId/Messages/ResponseBase.cs b/src/DotNetOpenAuth/OpenId/Messages/ResponseBase.cs
new file mode 100644
index 0000000..51326a3
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Messages/ResponseBase.cs
@@ -0,0 +1,88 @@
+//-----------------------------------------------------------------------
+// <copyright file="ResponseBase.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.Messages {
+	using System;
+	using System.Collections.Generic;
+	using DotNetOpenAuth.Messaging;
+
+	/// <summary>
+	/// A common base class for OpenID response messages.
+	/// </summary>
+	internal class ResponseBase : IProtocolMessage {
+		/// <summary>
+		/// The openid.ns parameter in the message.
+		/// </summary>
+		/// <value>"http://specs.openid.net/auth/2.0" </value>
+		/// <remarks>
+		/// OpenID 2.0 Section 5.1.2: 
+		/// This particular value MUST be present for the response to be a valid OpenID 2.0 response. 
+		/// Future versions of the specification may define different values in order to allow message 
+		/// recipients to properly interpret the request. 
+		/// </remarks>
+		[MessagePart("ns", IsRequired = true, AllowEmpty = false)]
+#pragma warning disable 0414 // read by reflection
+		private readonly string OpenIdNamespace = Protocol.OpenId2Namespace;
+#pragma warning restore 0414
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="ResponseBase"/> class.
+		/// </summary>
+		protected ResponseBase() {
+		}
+
+		#region IProtocolMessage Members
+
+		/// <summary>
+		/// Gets the version of the protocol this message is prepared to implement.
+		/// </summary>
+		/// <value>Version 2.0</value>
+		public Version ProtocolVersion {
+			get { return new Version(2, 0); }
+		}
+
+		/// <summary>
+		/// Gets the level of protection this message requires.
+		/// </summary>
+		/// <value><see cref="MessageProtections.None"/></value>
+		public MessageProtections RequiredProtection {
+			get { return MessageProtections.None; }
+		}
+
+		/// <summary>
+		/// Gets a value indicating whether this is a direct or indirect message.
+		/// </summary>
+		/// <value><see cref="MessageTransport.Direct"/></value>
+		public MessageTransport Transport {
+			get { return MessageTransport.Direct; }
+		}
+
+		/// <summary>
+		/// Gets the extra, non-OAuth parameters included in the message.
+		/// </summary>
+		/// <value>An empty dictionary.</value>
+		public IDictionary<string, string> ExtraData {
+			get { return EmptyDictionary<string, string>.Instance; }
+		}
+
+		/// <summary>
+		/// Checks the message state for conformity to the protocol specification
+		/// and throws an exception if the message is invalid.
+		/// </summary>
+		/// <remarks>
+		/// 	<para>Some messages have required fields, or combinations of fields that must relate to each other
+		/// in specialized ways.  After deserializing a message, this method checks the state of the
+		/// message to see if it conforms to the protocol.</para>
+		/// 	<para>Note that this property should <i>not</i> check signatures or perform any state checks
+		/// outside this scope of this particular message.</para>
+		/// </remarks>
+		/// <exception cref="ProtocolException">Thrown if the message is invalid.</exception>
+		public virtual void EnsureValidMessage() {
+		}
+
+		#endregion
+	}
+}
diff --git a/src/DotNetOpenAuth/OpenId/OpenIdStrings.Designer.cs b/src/DotNetOpenAuth/OpenId/OpenIdStrings.Designer.cs
new file mode 100644
index 0000000..2e434b6
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/OpenIdStrings.Designer.cs
@@ -0,0 +1,72 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:2.0.50727.3053
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId {
+    using System;
+    
+    
+    /// <summary>
+    ///   A strongly-typed resource class, for looking up localized strings, etc.
+    /// </summary>
+    // This class was auto-generated by the StronglyTypedResourceBuilder
+    // class via a tool like ResGen or Visual Studio.
+    // To add or remove a member, edit your .ResX file then rerun ResGen
+    // with the /str option, or rebuild your VS project.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "2.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    internal class OpenIdStrings {
+        
+        private static global::System.Resources.ResourceManager resourceMan;
+        
+        private static global::System.Globalization.CultureInfo resourceCulture;
+        
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal OpenIdStrings() {
+        }
+        
+        /// <summary>
+        ///   Returns the cached ResourceManager instance used by this class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Resources.ResourceManager ResourceManager {
+            get {
+                if (object.ReferenceEquals(resourceMan, null)) {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("DotNetOpenAuth.OpenId.OpenIdStrings", typeof(OpenIdStrings).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+        
+        /// <summary>
+        ///   Overrides the current thread's CurrentUICulture property for all
+        ///   resource lookups using this strongly typed resource class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Globalization.CultureInfo Culture {
+            get {
+                return resourceCulture;
+            }
+            set {
+                resourceCulture = value;
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Unless using transport layer encryption, &quot;no-encryption&quot; MUST NOT be used..
+        /// </summary>
+        internal static string NoEncryptionSessionRequiresHttps {
+            get {
+                return ResourceManager.GetString("NoEncryptionSessionRequiresHttps", resourceCulture);
+            }
+        }
+    }
+}
diff --git a/src/DotNetOpenAuth/OpenId/OpenIdStrings.resx b/src/DotNetOpenAuth/OpenId/OpenIdStrings.resx
new file mode 100644
index 0000000..fa7c82b
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/OpenIdStrings.resx
@@ -0,0 +1,123 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="NoEncryptionSessionRequiresHttps" xml:space="preserve">
+    <value>Unless using transport layer encryption, "no-encryption" MUST NOT be used.</value>
+  </data>
+</root>
\ No newline at end of file
diff --git a/src/DotNetOpenAuth/OpenId/Protocol.cs b/src/DotNetOpenAuth/OpenId/Protocol.cs
new file mode 100644
index 0000000..551c05a
--- /dev/null
+++ b/src/DotNetOpenAuth/OpenId/Protocol.cs
@@ -0,0 +1,17 @@
+//-----------------------------------------------------------------------
+// <copyright file="Protocol.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId {
+	/// <summary>
+	/// OpenID Protocol constants
+	/// </summary>
+	internal class Protocol {
+		/// <summary>
+		/// The value of the openid.ns parameter in the OpenID 2.0 specification.
+		/// </summary>
+		internal const string OpenId2Namespace = "http://specs.openid.net/auth/2.0";
+	}
+}