Add source code

TetheringHider/Services/AuthenticationService.swift

@@ -0,0 +1,53 @@
+import Foundation
+import LocalAuthentication
+
+enum AuthenticationError: LocalizedError {
+    case biometricsNotAvailable
+    case authenticationFailed(String)
+    case userCancelled
+    
+    var errorDescription: String? {
+        switch self {
+        case .biometricsNotAvailable:
+            return "Touch ID is not available on this device."
+        case .authenticationFailed(let reason):
+            return "Authentication failed: \(reason)"
+        case .userCancelled:
+            return "Authentication was cancelled."
+        }
+    }
+}
+
+struct AuthenticationService: Sendable {
+    
+    /// Attempts biometric authentication (Touch ID) before proceeding.
+    /// Falls back gracefully if Touch ID is not available.
+    /// Returns true if authenticated, false if biometrics unavailable (will proceed to admin dialog).
+    func authenticateWithBiometrics() async throws -> Bool {
+        let context = LAContext()
+        var error: NSError?
+        
+        guard context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) else {
+            // Touch ID not available — skip biometric step, will use admin dialog
+            return true
+        }
+        
+        do {
+            let success = try await context.evaluatePolicy(
+                .deviceOwnerAuthenticationWithBiometrics,
+                localizedReason: "Authenticate to modify system TTL value"
+            )
+            return success
+        } catch let authError as LAError {
+            switch authError.code {
+            case .userCancel, .appCancel:
+                throw AuthenticationError.userCancelled
+            case .userFallback:
+                // User chose to use password — allow proceeding to admin dialog
+                return true
+            default:
+                throw AuthenticationError.authenticationFailed(authError.localizedDescription)
+            }
+        }
+    }
+}