Added support for Exclusion List for WebAuthN.

Fixes #1285

Client/U2FExtensions.swift

@@ -243,6 +243,29 @@ class U2FExtensions: NSObject {
             ]
             makeCredentialRequest.options = makeOptions
 
+            let exclusionList: [Any] = publicKey.excludeCredentials.compactMap({
+                let credentialDescriptor = YKFFIDO2PublicKeyCredentialDescriptor()
+                guard let credentialIdData = Data(base64Encoded: $0.id) else {
+                    return nil
+                }
+
+                credentialDescriptor.credentialId = credentialIdData
+                credentialDescriptor.credentialType = {
+                    let credType = YKFFIDO2PublicKeyCredentialType()
+                    credType.name = "public-key"
+                    return credType
+                }()
+
+                return credentialDescriptor
+            })
+
+            guard exclusionList.count == publicKey.excludeCredentials.count else {
+                sendFIDO2AuthenticationError(handle: handle)
+                return
+            }
+
+            makeCredentialRequest.excludeList = exclusionList
+
             guard let fido2Service = YubiKitManager.shared.keySession.fido2Service else {
                 self.sendFIDO2RegistrationError(handle: handle)
                 return

Client/WebAuthN/WebAuthnRegisterRequest.swift

@@ -2,6 +2,12 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+
+struct PublicKeyCredentialDescriptor: Decodable {
+    let type: String
+    let id: String
+}
+
 struct WebAuthnRegisterRequest: Decodable {
     struct PublicKey: Decodable {
         struct PubKeyCredParams: Decodable {
@@ -31,6 +37,7 @@ struct WebAuthnRegisterRequest: Decodable {
         let user: User
         let rp: Rp
         let challenge: String
+        let excludeCredentials: [PublicKeyCredentialDescriptor]
     }
     let publicKey: PublicKey
 }