Added AttestationFormat enum.

samples/KristofferStrube.Blazor.WebAuthentication.WasmExample/Pages/Index.razor.cs

@@ -89,7 +89,7 @@ private async Task CreateCredential()
                     Timeout = 360000,
                     Hints = "client-device",
                     Attestation = AttestationConveyancePreference.Direct,
-                    AttestationFormats = ["tpm"]
+                    AttestationFormats = [AttestationFormat.Packed, AttestationFormat.AndroidKey, AttestationFormat.AndroidSafetyNet, AttestationFormat.TPM]
                 }
             };
             credential = await container.CreateAsync(options) is { } c ? new PublicKeyCredential(c) : null;

src/KristofferStrube.Blazor.WebAuthentication/AttestationStatements/AndroidSafetyNetAttestationStatement.cs

@@ -70,19 +70,19 @@ internal static AndroidSafetyNetAttestationStatement ReadAttestationStatement(Cb
         state = cborReader.PeekState();
         if (state is not CborReaderState.TextString)
         {
-            throw new FormatException($"Attestation Statement's packed format's second key was of type '{state}' but '{CborReaderState.TextString}' was expected.");
+            throw new FormatException($"Attestation Statement's safety net format's second key was of type '{state}' but '{CborReaderState.TextString}' was expected.");
         }
 
         label = cborReader.ReadTextString();
         if (label is not "response")
         {
-            throw new FormatException($"Attestation Statement's packed format's second key was '{label}' but 'response' was expected.");
+            throw new FormatException($"Attestation Statement's safety net format's second key was '{label}' but 'response' was expected.");
         }
 
         state = cborReader.PeekState();
         if (state is not CborReaderState.ByteString)
         {
-            throw new FormatException($"Attestation Statement's packed format's 'response' was of type '{state}' but '{CborReaderState.ByteString}' was expected.");
+            throw new FormatException($"Attestation Statement's safety net format's 'response' was of type '{state}' but '{CborReaderState.ByteString}' was expected.");
         }
 
         byte[] response = cborReader.ReadByteString();

src/KristofferStrube.Blazor.WebAuthentication/Converters/AttestationFormatConverter.cs

@@ -0,0 +1,37 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace KristofferStrube.Blazor.WebAuthentication.Converters;
+
+public class AttestationFormatConverter : JsonConverter<AttestationFormat>
+{
+    public override AttestationFormat Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        return reader.GetString() switch
+        {
+            "packed" => AttestationFormat.Packed,
+            "tpm" => AttestationFormat.TPM,
+            "android-key" => AttestationFormat.AndroidKey,
+            "android-safetynet" => AttestationFormat.AndroidSafetyNet,
+            "fido-u2f" => AttestationFormat.FidoU2F,
+            "apple" => AttestationFormat.Apple,
+            "none" => AttestationFormat.None,
+            var value => throw new ArgumentException($"Value '{value}' was not a valid {nameof(AttestationFormat)}.")
+        };
+    }
+
+    public override void Write(Utf8JsonWriter writer, AttestationFormat value, JsonSerializerOptions options)
+    {
+        writer.WriteStringValue(value switch
+        {
+            AttestationFormat.Packed => "packed",
+            AttestationFormat.TPM => "tpm",
+            AttestationFormat.AndroidKey => "android-key",
+            AttestationFormat.AndroidSafetyNet => "android-safetynet",
+            AttestationFormat.FidoU2F => "fido-u2f",
+            AttestationFormat.Apple => "apple",
+            AttestationFormat.None => "none",
+            _ => throw new ArgumentException($"Value '{value}' was not a valid {nameof(AttestationFormat)}.")
+        });
+    }
+}

src/KristofferStrube.Blazor.WebAuthentication/Options/AttestationFormat.cs

@@ -0,0 +1,44 @@
+using KristofferStrube.Blazor.WebAuthentication.Converters;
+using System.Text.Json.Serialization;
+
+namespace KristofferStrube.Blazor.WebAuthentication;
+
+/// <summary>
+/// Authenticators may implement various transports for communicating with clients.
+/// This enum defines hints as to how clients might communicate with a particular authenticator in order to obtain an assertion for a specific credential.
+/// </summary>
+/// <remarks><see href="https://www.iana.org/assignments/webauthn/webauthn.xhtml">See the API definition here</see>.</remarks>
+[JsonConverter(typeof(AttestationFormatConverter))]
+public enum AttestationFormat
+{
+    /// <summary>
+    /// The "packed" attestation statement format is a WebAuthn-optimized format for attestation. It uses a very compact but still extensible encoding method.
+    /// This format is implementable by authenticators with limited resources (e.g., secure elements).	
+    /// </summary>
+    Packed,
+    /// <summary>
+    /// The TPM attestation statement format returns an attestation statement in the same format as the packed attestation statement format,
+    /// although the rawData and signature fields are computed differently.	
+    /// </summary>
+    TPM,
+    /// <summary>
+    /// Platform authenticators on versions "N", and later, may provide this proprietary "hardware attestation" statement.	
+    /// </summary>
+    AndroidKey,
+    /// <summary>
+    /// Android-based platform authenticators MAY produce an attestation statement based on the Android SafetyNet API.	
+    /// </summary>
+    AndroidSafetyNet,
+    /// <summary>
+    /// Used with FIDO U2F authenticators
+    /// </summary>
+    FidoU2F,
+    /// <summary>
+    /// Used with Apple devices' platform authenticators	
+    /// </summary>
+    Apple,
+    /// <summary>
+    /// Used to replace any authenticator-provided attestation statement when a WebAuthn Relying Party indicates it does not wish to receive attestation information.	
+    /// </summary>
+    None,
+}

src/KristofferStrube.Blazor.WebAuthentication/Options/PublicKeyCredentialCreationOptions.cs

@@ -2,6 +2,10 @@
 
 namespace KristofferStrube.Blazor.WebAuthentication;
 
+/// <summary>
+/// The options specific to the public key of <see cref="CredentialCreationOptions"/>.
+/// </summary>
+/// <remarks><see href="https://www.w3.org/TR/webauthn-3/#dictdef-publickeycredentialcreationoptions">See the API definition here</see>.</remarks>
 public class PublicKeyCredentialCreationOptions
 {
     [JsonPropertyName("rp")]
@@ -27,7 +31,12 @@ public class PublicKeyCredentialCreationOptions
     [JsonPropertyName("attestation")]
     public AttestationConveyancePreference Attestation { get; set; }
 
+    /// <summary>
+    /// The Relying Party can use this optional member to specify a preference regarding the attestation statement format used by the authenticator.
+    /// Values are ordered from most preferable to least preferable.
+    /// This parameter is advisory and the authenticator and could use an attestation statement not enumerated in this parameter.
+    /// </summary>
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     [JsonPropertyName("attestationFormats")]
-    public string[]? AttestationFormats { get; set; }
+    public AttestationFormat[]? AttestationFormats { get; set; }
 }