Added an AuthenticatorAttachment enumeration

Author: dimitribouniol

Sources/WebAuthn/Ceremonies/Authentication/AuthenticationCredential.swift

@@ -29,7 +29,7 @@ public struct AuthenticationCredential {
 
     /// Reports the authenticator attachment modality in effect at the time the navigator.credentials.create() or
     /// navigator.credentials.get() methods successfully complete
-    public let authenticatorAttachment: String?
+    public let authenticatorAttachment: AuthenticatorAttachment?
 
     /// Value will always be "public-key" (for now)
     public let type: String
@@ -42,7 +42,7 @@ extension AuthenticationCredential: Decodable {
         id = try container.decode(URLEncodedBase64.self, forKey: .id)
         rawID = try container.decodeBytesFromURLEncodedBase64(forKey: .rawID)
         response = try container.decode(AuthenticatorAssertionResponse.self, forKey: .response)
-        authenticatorAttachment = try container.decodeIfPresent(String.self, forKey: .authenticatorAttachment)
+        authenticatorAttachment = try container.decodeIfPresent(AuthenticatorAttachment.self, forKey: .authenticatorAttachment)
         type = try container.decode(String.self, forKey: .type)
     }
 

Sources/WebAuthn/Ceremonies/Shared/AuthenticatorAttachment.swift

@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the WebAuthn Swift open source project
+//
+// Copyright (c) 2024 the WebAuthn Swift project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of WebAuthn Swift project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+/// An authenticators' attachment modalities.
+///
+/// Relying Parties use this to express a preferred authenticator attachment modality when registering a credential, and clients use this to report the authenticator attachment modality used to complete a registration or authentication ceremony.
+/// - SeeAlso: [WebAuthn Level 3 Editor's Draft §5.4.5. Authenticator Attachment Enumeration (enum AuthenticatorAttachment)](https://w3c.github.io/webauthn/#enum-attachment)
+/// - SeeAlso: [WebAuthn Level 3 Editor's Draft §6.2.1. Authenticator Attachment Modality](https://w3c.github.io/webauthn/#sctn-authenticator-attachment-modality)
+///
+public struct AuthenticatorAttachment: UnreferencedStringEnumeration {
+    public var rawValue: String
+    public init(_ rawValue: String) {
+        self.rawValue = rawValue
+    }
+    
+    /// A platform authenticator is attached using a client device-specific transport, called platform attachment, and is usually not removable from the client device. A public key credential bound to a platform authenticator is called a platform credential.
+    /// - SeeAlso: [WebAuthn Level 3 Editor's Draft §6.2.1. Authenticator Attachment Modality](https://w3c.github.io/webauthn/#platform-attachment)
+    public static let platform: Self = "platform"
+    
+    /// A roaming authenticator is attached using cross-platform transports, called cross-platform attachment. Authenticators of this class are removable from, and can "roam" between, client devices. A public key credential bound to a roaming authenticator is called a roaming credential.
+    /// - SeeAlso: [WebAuthn Level 3 Editor's Draft §6.2.1. Authenticator Attachment Modality](https://w3c.github.io/webauthn/#cross-platform-attachment)
+    public static let crossPlatform: Self = "cross-platform"
+}

Tests/WebAuthnTests/WebAuthnManagerAuthenticationTests.swift

@@ -165,7 +165,7 @@ final class WebAuthnManagerAuthenticationTests: XCTestCase {
         signature: [UInt8] = TestECCKeyPair.signature,
         userHandle: [UInt8]? = "36323638424436452d303831452d344331312d413743332d334444304146333345433134".hexadecimal!,
         attestationObject: [UInt8]? = nil,
-        authenticatorAttachment: String? = "platform",
+        authenticatorAttachment: AuthenticatorAttachment? = .platform,
         type: String = "public-key",
         expectedChallenge: [UInt8] = TestConstants.mockChallenge,
         credentialPublicKey: [UInt8] = TestCredentialPublicKeyBuilder().validMock().buildAsByteArray(),

Tests/WebAuthnTests/WebAuthnManagerIntegrationTests.swift

@@ -143,7 +143,7 @@ final class WebAuthnManagerIntegrationTests: XCTestCase {
                 userHandle: mockUser.id,
                 attestationObject: nil
             ),
-            authenticatorAttachment: "platform",
+            authenticatorAttachment: .platform,
             type: "public-key"
         )