Encrypted Authorization response (#170)

* encryption Signed-off-by: Kevin <[email protected]> * fix build Signed-off-by: Kevin <[email protected]> --------- Signed-off-by: Kevin <[email protected]>
openwallet-foundation-labs · Aug 23, 2024 · 49afecf · 49afecf
1 parent ba3c20a
commit 49afecf
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Showing 13 changed files with 173 additions and 38 deletions.
diff --git a/src/WalletFramework.Core/Base64Url/Base64UrlString.cs b/src/WalletFramework.Core/Base64Url/Base64UrlString.cs
@@ -5,9 +5,11 @@ namespace WalletFramework.Core.Base64Url;
 public readonly struct Base64UrlString
 {
     private string Value { get; }
-
+    
     public byte[] AsByteArray => Base64UrlEncoder.DecodeBytes(Value);
 
+    public string AsString => Value;
+
     private Base64UrlString(string value)
     {
         Value = value;

diff --git a/src/WalletFramework.Core/WalletFramework.Core.csproj b/src/WalletFramework.Core/WalletFramework.Core.csproj
@@ -5,6 +5,7 @@
         <Nullable>enable</Nullable>
     </PropertyGroup>
     <ItemGroup>
+      <PackageReference Include="jose-jwt" Version="5.0.0" />
       <PackageReference Include="LanguageExt.Core" Version="4.4.9" />
       <PackageReference Include="Microsoft.IdentityModel.Tokens" Version="8.0.1" />
       <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />

diff --git a/src/WalletFramework.MdocLib/Mdoc.cs b/src/WalletFramework.MdocLib/Mdoc.cs
@@ -104,11 +104,10 @@ public static Validation<Mdoc> FromIssuerSigned(string base64UrlencodedCborByteS
         });
 
         var validateIntegrity = new List<Validator<Mdoc>>
-            {
-                MdocFun.DocTypeMatches,
-                MdocFun.DigestsMatch
-            }
-            .AggregateValidators();
+        {
+            MdocFun.DocTypeMatches,
+            MdocFun.DigestsMatch
+        }.AggregateValidators();
 
         return 
             from bytes in decodeBase64Url(base64UrlencodedCborByteString)

diff --git a/src/WalletFramework.Oid4Vc/Oid4Vci/Implementations/Oid4VciClientService.cs b/src/WalletFramework.Oid4Vc/Oid4Vci/Implementations/Oid4VciClientService.cs
@@ -136,8 +136,7 @@ from issState in code.IssuerState
             null,
             null);
 
-        var authServerMetadata = 
-            await FetchAuthorizationServerMetadataAsync(issuerMetadata);
+        var authServerMetadata = await FetchAuthorizationServerMetadataAsync(issuerMetadata);
 
         _httpClient.DefaultRequestHeaders.Clear();
         var response = await _httpClient.PostAsync(

diff --git a/src/WalletFramework.Oid4Vc/Oid4Vp/AuthResponse/Encryption/EncryptedAuthorizationResponse.cs b/src/WalletFramework.Oid4Vc/Oid4Vp/AuthResponse/Encryption/EncryptedAuthorizationResponse.cs
@@ -0,0 +1,50 @@
+using Hyperledger.Aries.Extensions;
+using Jose;
+using LanguageExt;
+using WalletFramework.Oid4Vc.Oid4Vp.Jwk;
+using WalletFramework.Oid4Vc.Oid4Vp.Models;
+
+namespace WalletFramework.Oid4Vc.Oid4Vp.AuthResponse.Encryption;
+
+public record EncryptedAuthorizationResponse(string Jwe)
+{
+    public override string ToString() => Jwe;
+}
+
+public static class EncryptedAuthorizationResponseFun
+{
+    public static FormUrlEncodedContent ToFormUrl(this EncryptedAuthorizationResponse response)
+    {
+        var content = new Dictionary<string, string>
+        {
+            { "response", response.ToString() },
+        };
+
+        return new FormUrlEncodedContent(content);
+    }
+
+    public static EncryptedAuthorizationResponse Encrypt(
+        this AuthorizationResponse response,
+        AuthorizationRequest authorizationRequest,
+        Option<Nonce> mdocNonce)
+    {
+        var verifierPubKey = authorizationRequest.ClientMetadata!.Jwks.First();
+
+        var headers = new Dictionary<string, object>
+        {
+            { "apv", authorizationRequest.Nonce },
+            { "kid", verifierPubKey.Kid }
+        };
+
+        mdocNonce.IfSome(nonce => headers.Add("apu", nonce.AsBase64Url.ToString()));
+
+        var jwe = JWE.EncryptBytes(
+            response.ToJson().GetUTF8Bytes(),
+            new [] { new JweRecipient(JweAlgorithm.ECDH_ES, verifierPubKey.ToEcdh()) },
+            JweEncryption.A256GCM,
+            mode: SerializationMode.Compact,
+            extraProtectedHeaders: headers);
+
+        return new EncryptedAuthorizationResponse(jwe);
+    }
+}
diff --git a/src/WalletFramework.Oid4Vc/Oid4Vp/Jwk/JwkFun.cs b/src/WalletFramework.Oid4Vc/Oid4Vp/Jwk/JwkFun.cs
@@ -0,0 +1,23 @@
+using System.Security.Cryptography;
+using Microsoft.IdentityModel.Tokens;
+
+namespace WalletFramework.Oid4Vc.Oid4Vp.Jwk;
+
+public static class JwkFun
+{
+    public static ECDiffieHellman ToEcdh(this JsonWebKey jwk)
+    {
+        var ecParameters = new ECParameters
+        {
+            Q =
+            {
+                X = Base64UrlEncoder.DecodeBytes(jwk.X),
+                Y = Base64UrlEncoder.DecodeBytes(jwk.Y)
+            },
+            // TODO: Map curve from jwk
+            Curve = ECCurve.NamedCurves.nistP256
+        };
+
+        return ECDiffieHellman.Create(ecParameters);
+    }
+}
diff --git a/src/WalletFramework.Oid4Vc/Oid4Vp/Models/AuthorizationRequest.cs b/src/WalletFramework.Oid4Vc/Oid4Vp/Models/AuthorizationRequest.cs
@@ -11,8 +11,8 @@ namespace WalletFramework.Oid4Vc.Oid4Vp.Models;
 /// </summary>
 public record AuthorizationRequest
 {
-    private const string DirectPost = "direct_post";
-    private const string DirectPostJwt = "direct_post.jwt";
+    public const string DirectPost = "direct_post";
+    public const string DirectPostJwt = "direct_post.jwt";
 
     private const string VpToken = "vp_token";
 
@@ -45,6 +45,9 @@ public record AuthorizationRequest
     /// </summary>
     [JsonProperty("response_uri")]
     public string ResponseUri { get; }
+
+    [JsonProperty("response_mode")]
+    public string ResponseMode { get; }
 
     /// <summary>
     ///     Gets the client metadata. Contains the Verifier metadata.
@@ -89,6 +92,7 @@ private AuthorizationRequest(
         string clientId,
         string nonce,
         string responseUri,
+        string responseMode,
         ClientMetadata? clientMetadata,
         string? clientMetadataUri,
         string? scope,
@@ -101,6 +105,7 @@ private AuthorizationRequest(
         Nonce = nonce;
         PresentationDefinition = presentationDefinition;
         ResponseUri = responseUri;
+        ResponseMode = responseMode;
         Scope = scope;
         State = state;
     }

diff --git a/src/WalletFramework.Oid4Vc/Oid4Vp/Models/AuthorizationResponse.cs b/src/WalletFramework.Oid4Vc/Oid4Vp/Models/AuthorizationResponse.cs
@@ -1,4 +1,5 @@
 using Newtonsoft.Json;
+using WalletFramework.Oid4Vc.Oid4Vp.PresentationExchange.Models;
 
 namespace WalletFramework.Oid4Vc.Oid4Vp.Models;
 
@@ -10,18 +11,30 @@ public class AuthorizationResponse
     /// <summary>
     ///     Gets or sets the VP Token.
     /// </summary>
-    [JsonProperty ("vp_token")]
+    [JsonProperty("vp_token")]
     public string VpToken { get; set; } = null!;
 
     /// <summary>
     ///   Gets or sets the Presentation Submission.
     /// </summary>
-    [JsonProperty ("presentation_submission")]
-    public string PresentationSubmission { get; set; } = null!;
+    [JsonProperty("presentation_submission")]
+    public PresentationSubmission PresentationSubmission { get; set; } = null!;
 
     /// <summary>
     ///     Gets or sets the State.
     /// </summary>
-    [JsonProperty ("state", NullValueHandling = NullValueHandling.Ignore)]
-    public string? State { get; set; } = null!;
+    [JsonProperty("state", NullValueHandling = NullValueHandling.Ignore)]
+    public string? State { get; set; }
+}
+
+public static class AuthorizationResponseFun
+{
+    public static FormUrlEncodedContent ToFormUrl(this AuthorizationResponse authorizationResponse)
+    {
+        var json = JsonConvert.SerializeObject(authorizationResponse);
+        var nameValueCollection = 
+            JsonConvert.DeserializeObject<Dictionary<string, string>>(json)!.ToList();
+
+        return new FormUrlEncodedContent(nameValueCollection);
+    }
 }
diff --git a/src/WalletFramework.Oid4Vc/Oid4Vp/Models/ClientJwksConverter.cs b/src/WalletFramework.Oid4Vc/Oid4Vp/Models/ClientJwksConverter.cs
@@ -0,0 +1,40 @@
+using Microsoft.IdentityModel.Tokens;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using WalletFramework.Core.Functional;
+using WalletFramework.Core.Json;
+
+namespace WalletFramework.Oid4Vc.Oid4Vp.Models;
+
+public class ClientJwksConverter : JsonConverter<List<JsonWebKey>>
+{
+    public override bool CanRead => true;
+
+    public override bool CanWrite => false;
+
+    public override void WriteJson(JsonWriter writer, List<JsonWebKey>? value, JsonSerializer serializer)
+    {
+        throw new NotImplementedException();
+    }
+
+    public override List<JsonWebKey> ReadJson(
+        JsonReader reader,
+        Type objectType,
+        List<JsonWebKey>? existingValue,
+        bool hasExistingValue,
+        JsonSerializer serializer)
+    {
+        var json = JObject.Load(reader);
+        var validKeysArray =
+            from keys in json.GetByKey("keys")
+            from keysArray in keys.ToJArray()
+            select keysArray;
+
+        var result = validKeysArray.OnSuccess(keysArray =>
+        {
+            return keysArray.Select(keyToken => JsonWebKey.Create(keyToken.ToString())).ToList();
+        }).UnwrapOrThrow();
+
+        return result;
+    }
+}
diff --git a/src/WalletFramework.Oid4Vc/Oid4Vp/Models/ClientMetadata.cs b/src/WalletFramework.Oid4Vc/Oid4Vp/Models/ClientMetadata.cs
@@ -1,11 +1,11 @@
+using Microsoft.IdentityModel.Tokens;
 using Newtonsoft.Json;
 
 namespace WalletFramework.Oid4Vc.Oid4Vp.Models;
 
 /// <summary>
 ///    Represents the metadata of a client (verifier).
 /// </summary>
-// TODO: Rename this to VerifierMetadata
 public record ClientMetadata
 {
     /// <summary>
@@ -38,8 +38,9 @@ public record ClientMetadata
     [JsonProperty("logo_uri")]
     public string? LogoUri { get; }
 
-    // TODO: JWKs of the verifier
-    // public List<JWK> PublicKeys { get; }
+    [JsonProperty("jwks")]
+    [JsonConverter(typeof(ClientJwksConverter))]
+    public List<JsonWebKey> Jwks { get; }
 
     /// <summary>
     ///     The URI to a human-readable privacy policy document for the client (verifier).
@@ -54,7 +55,15 @@ public record ClientMetadata
     public string? TosUri { get; }
 
     [JsonConstructor]
-    private ClientMetadata(string? clientName, string? clientUri, string[]? contacts, string? logoUri, string? policyUri, string? tosUri, string[] redirectUris)
+    private ClientMetadata(
+        string? clientName,
+        string? clientUri,
+        string[]? contacts,
+        string? logoUri,
+        string? policyUri,
+        string? tosUri,
+        string[] redirectUris,
+        List<JsonWebKey> jwks)
     {
         ClientName = clientName;
         ClientUri = clientUri;
@@ -63,5 +72,6 @@ private ClientMetadata(string? clientName, string? clientUri, string[]? contacts
         PolicyUri = policyUri;
         TosUri = tosUri;
         RedirectUris = redirectUris;
+        Jwks = jwks;
     }
 }
diff --git a/src/WalletFramework.Oid4Vc/Oid4Vp/Services/Oid4VpClientService.cs b/src/WalletFramework.Oid4Vc/Oid4Vp/Services/Oid4VpClientService.cs
@@ -12,6 +12,7 @@
 using WalletFramework.MdocLib.Security;
 using WalletFramework.MdocVc;
 using WalletFramework.Oid4Vc.Oid4Vci.CredConfiguration.Models;
+using WalletFramework.Oid4Vc.Oid4Vp.AuthResponse.Encryption;
 using WalletFramework.Oid4Vc.Oid4Vp.Models;
 using WalletFramework.Oid4Vc.Oid4Vp.PresentationExchange.Services;
 using WalletFramework.SdJwtVc.Models.Records;
@@ -126,6 +127,7 @@ from path in field.Path.Select(path => path.TrimStart('$', '.'))
 
                     var toDisclose = claims.Select(claim =>
                     {
+                        // TODO: This is needed because in mdoc the requested attributes look like this: $[Namespace][ElementId]. Refactor this more clean
                         var keys = claim.Split(new[] { "[", "]" }, StringSplitOptions.RemoveEmptyEntries);
 
                         var nameSpace = NameSpace.ValidNameSpace(keys[0]).UnwrapOrThrow();
@@ -170,36 +172,28 @@ from path in field.Path.Select(path => path.TrimStart('$', '.'))
             presentationMaps.Select(tuple => (tuple.InputDescriptorId, tuple.Presentation, tuple.Format)).ToArray()
         );
 
-        var httpClient = _httpClientFactory.CreateClient();
-        httpClient.DefaultRequestHeaders.Clear();
-        if (clientAttestation is not null)
-            httpClient.AddClientAttestationPopHeader(clientAttestation);
-
-        var json = SerializeObject(authorizationResponse);
-        var nameValueCollection = DeserializeObject<Dictionary<string, string>>(json)!.ToList();
-
-        // TODO: This is only a hack until the encryption response is implemented
-        mdocNonce.IfSome(nonce =>
+        var content = authorizationRequest.ResponseMode switch
         {
-            var pair = new KeyValuePair<string, string>("apu", nonce.AsBase64Url.ToString());
-            nameValueCollection.Add(pair);
-        });
-
-        var content = new FormUrlEncodedContent(nameValueCollection);
+            AuthorizationRequest.DirectPost => authorizationResponse.ToFormUrl(),
+            AuthorizationRequest.DirectPostJwt => authorizationResponse.Encrypt(authorizationRequest, mdocNonce).ToFormUrl(),
+            _ => throw new ArgumentOutOfRangeException(nameof(authorizationRequest.ResponseMode))
+        };
 
         var message = new HttpRequestMessage
         {
             RequestUri = new Uri(authorizationRequest.ResponseUri),
             Method = HttpMethod.Post,
             Content = content
         };
-            
+
         // TODO: Introduce timeout
+        var httpClient = _httpClientFactory.CreateClient();
+        httpClient.DefaultRequestHeaders.Clear();
         var responseMessage = await httpClient.SendAsync(message);
         if (!responseMessage.IsSuccessStatusCode)
         {
             var str = await responseMessage.Content.ReadAsStringAsync();
-            throw new InvalidOperationException($"Authorization Response could not be sent with message {str}");
+            throw new InvalidOperationException($"Authorization Response failed with message {str}");
         }
 
         var presentedCredentials = presentationMaps.Select(presentationMap =>

diff --git a/src/WalletFramework.Oid4Vc/Oid4Vp/Services/Oid4VpHaipClient.cs b/src/WalletFramework.Oid4Vc/Oid4Vp/Services/Oid4VpHaipClient.cs
@@ -56,7 +56,7 @@ public async Task<AuthorizationResponse> CreateAuthorizationResponseAsync(
 
         return new AuthorizationResponse
         {
-            PresentationSubmission = SerializeObject(presentationSubmission),
+            PresentationSubmission = presentationSubmission,
             VpToken = vpToken.Count > 1 ? SerializeObject(vpToken) : vpToken[0],
             State = authorizationRequest.State
         };

diff --git a/src/WalletFramework.Oid4Vc/WalletFramework.Oid4Vc.csproj b/src/WalletFramework.Oid4Vc/WalletFramework.Oid4Vc.csproj
@@ -1,5 +1,4 @@
 <Project Sdk="Microsoft.NET.Sdk">
-
     <PropertyGroup>
         <TargetFramework>netstandard2.1</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>