Initial implementation of using YubiKey for decryption (#533)

passKit/Helpers/YubiKeyConnection.swift

@@ -0,0 +1,63 @@
+//
+//  YubiKeyConnection.swift
+//  passKit
+//
+//  Copyright © 2022 Bob Sun. All rights reserved.
+//
+
+import Foundation
+import YubiKit
+
+public class YubiKeyConnection: NSObject {
+    public static let shared = YubiKeyConnection()
+
+    var accessoryConnection: YKFAccessoryConnection?
+    var nfcConnection: YKFNFCConnection?
+    var connectionCallback: ((_ connection: YKFConnectionProtocol) -> Void)?
+    var cancellationCallback: ((_ error: Error) -> Void)?
+
+    override init() {
+        super.init()
+        YubiKitManager.shared.delegate = self
+        YubiKitManager.shared.startAccessoryConnection()
+    }
+
+    public func connection(cancellation: @escaping (_ error: Error) -> Void, completion: @escaping (_ connection: YKFConnectionProtocol) -> Void) {
+        if let connection = accessoryConnection {
+            completion(connection)
+        } else {
+            connectionCallback = completion
+            if #available(iOSApplicationExtension 13.0, *) {
+                YubiKitManager.shared.startNFCConnection()
+            }
+        }
+        cancellationCallback = cancellation
+    }
+}
+
+extension YubiKeyConnection: YKFManagerDelegate {
+    public func didConnectNFC(_ connection: YKFNFCConnection) {
+        nfcConnection = connection
+        if let callback = connectionCallback {
+            callback(connection)
+        }
+    }
+
+    public func didDisconnectNFC(_: YKFNFCConnection, error _: Error?) {
+        nfcConnection = nil
+    }
+
+    public func didConnectAccessory(_ connection: YKFAccessoryConnection) {
+        accessoryConnection = connection
+    }
+
+    public func didDisconnectAccessory(_: YKFAccessoryConnection, error _: Error?) {
+        accessoryConnection = nil
+    }
+
+    public func didFailConnectingNFC(_ error: Error) {
+        if let callback = cancellationCallback {
+            callback(error)
+        }
+    }
+}