feature: add access control parameter for apple

Author: juliansteenbakker

flutter_secure_storage/lib/options/apple_options.dart

@@ -30,6 +30,37 @@ enum KeychainAccessibility {
   first_unlock_this_device,
 }
 
+/// Keychain access control flags that define security conditions for accessing items.
+/// These flags can be combined to create complex access control policies.
+enum AccessControlFlag {
+  /// Constraint to access an item with a passcode.
+  devicePasscode,
+
+  /// Constraint to access an item with biometrics (Touch ID/Face ID).
+  biometryAny,
+
+  /// Constraint to access an item with the currently enrolled biometrics.
+  biometryCurrentSet,
+
+  /// Constraint to access an item with either biometry or passcode.
+  userPresence,
+
+  /// Constraint to access an item with a paired watch.
+  watch,
+
+  /// Combine multiple constraints with an OR operation.
+  or,
+
+  /// Combine multiple constraints with an AND operation.
+  and,
+
+  /// Use an application-provided password for encryption.
+  applicationPassword,
+
+  /// Enable private key usage for signing operations.
+  privateKeyUsage,
+}
+
 /// Specific options for Apple platform.
 abstract class AppleOptions extends Options {
   /// Creates an instance of `AppleOptions` with configurable parameters
@@ -49,7 +80,7 @@ abstract class AppleOptions extends Options {
     this.resultLimit,
     this.shouldReturnPersistentReference,
     this.authenticationUIBehavior,
-    this.accessControlSettings,
+    this.accessControlFlags = const [],
   });
 
   /// The default account name associated with the keychain items.
@@ -130,11 +161,27 @@ abstract class AppleOptions extends Options {
   /// Determines whether authentication prompts are displayed to the user.
   final String? authenticationUIBehavior;
 
-  /// `kSecAttrAccessControl`: **Shared or Unique**.
-  /// Specifies access control settings for the item
-  /// (e.g., biometrics, passcode).
-  /// Shared if multiple items use the same access control.
-  final String? accessControlSettings;
+  /// Keychain access control flags define security conditions for accessing items.
+  /// These flags can be combined to create custom security policies.
+  ///
+  /// ### Using Logical Operators:
+  /// - Use `AccessControlFlag.or` to allow access if **any** of the specified conditions are met.
+  /// - Use `AccessControlFlag.and` to require that **all** specified conditions are met.
+  ///
+  /// **Rules for Combining Flags:**
+  /// - Only one logical operator (`or` or `and`) can be used per combination.
+  /// - Logical operators should be placed after the security constraints.
+  ///
+  /// **Supported Flags:**
+  /// - `userPresence`: Requires user authentication via biometrics or passcode.
+  /// - `biometryAny`: Allows access with any enrolled biometrics.
+  /// - `biometryCurrentSet`: Requires currently enrolled biometrics.
+  /// - `devicePasscode`: Requires device passcode authentication.
+  /// - `watch`: Allows access with a paired Apple Watch.
+  /// - `privateKeyUsage`: Enables use of a private key for signing operations.
+  /// - `applicationPassword`: Uses an app-defined password for encryption.
+  ///
+  final List<AccessControlFlag> accessControlFlags;
 
   @override
   Map<String, String> toMap() => <String, String>{
@@ -156,7 +203,8 @@ abstract class AppleOptions extends Options {
           'shouldReturnPersistentReference': '$shouldReturnPersistentReference',
         if (authenticationUIBehavior != null)
           'authenticationUIBehavior': authenticationUIBehavior!,
-        if (accessControlSettings != null)
-          'accessControlSettings': accessControlSettings!,
+        if (accessControlFlags.isNotEmpty)
+          'accessControlFlags':
+              accessControlFlags.map((e) => e.name).toList().toString(),
       };
 }

flutter_secure_storage/lib/options/ios_options.dart

@@ -21,7 +21,7 @@ class IOSOptions extends AppleOptions {
     super.resultLimit,
     super.shouldReturnPersistentReference,
     super.authenticationUIBehavior,
-    super.accessControlSettings,
+    super.accessControlFlags,
   });
 
   /// A predefined `IosOptions` instance with default settings.

flutter_secure_storage/lib/options/macos_options.dart

@@ -20,7 +20,7 @@ class MacOsOptions extends AppleOptions {
     super.resultLimit,
     super.shouldReturnPersistentReference,
     super.authenticationUIBehavior,
-    super.accessControlSettings,
+    super.accessControlFlags,
     this.usesDataProtectionKeychain = true,
   });
 

flutter_secure_storage_darwin/darwin/flutter_secure_storage_darwin/Sources/flutter_secure_storage_darwin/FlutterSecureStorage.swift

@@ -60,8 +60,8 @@ struct KeychainQueryParameters {
     /// `kSecUseAuthenticationUI` (iOS/macOS): Controls how authentication UI is presented during secure operations.
     var authenticationUIBehavior: String?
 
-    /// `kSecAttrAccessControl` (iOS/macOS): Specifies access control settings (e.g., biometrics, passcode).
-    var accessControlSettings: SecAccessControl?
+    /// `accessControlFlags` (iOS/macOS): Specifies access control settings (e.g., biometrics, passcode).
+    var accessControlFlags: String?
 }
 
 /// Represents the response from a keychain operation.
@@ -88,6 +88,52 @@ class FlutterSecureStorage {
         default: return kSecAttrAccessibleWhenUnlocked
         }
     }
+    
+    /// Parses a string of comma-separated access control flags into SecAccessControlCreateFlags.
+    private func parseAccessControlFlags(_ flagString: String?) -> SecAccessControlCreateFlags {
+        guard let flagString = flagString else { return [] }
+        var flags: SecAccessControlCreateFlags = []
+        let flagList = flagString.split(separator: ",").map { $0.trimmingCharacters(in: .whitespaces) }
+        for dirtyFlag in flagList {
+            let flag = dirtyFlag.trimmingCharacters(in: CharacterSet(charactersIn: "[]"))
+               
+            switch flag {
+            case "userPresence":
+                flags.insert(.userPresence)
+            case "biometryAny":
+                flags.insert(.biometryAny)
+            case "biometryCurrentSet":
+                flags.insert(.biometryCurrentSet)
+            case "devicePasscode":
+                flags.insert(.devicePasscode)
+            case "or":
+                flags.insert(.or)
+            case "and":
+                flags.insert(.and)
+            case "privateKeyUsage":
+                flags.insert(.privateKeyUsage)
+            case "applicationPassword":
+                flags.insert(.applicationPassword)
+            default:
+                continue
+            }
+        }
+        return flags
+    }
+    
+    /// Creates an access control object based on the provided parameters.
+    private func createAccessControl(params: KeychainQueryParameters) -> SecAccessControl? {
+        guard let accessibilityLevel = params.accessibilityLevel else { return nil }
+        let protection = parseAccessibleAttr(accessibilityLevel)
+        let flags = parseAccessControlFlags(params.accessControlFlags)
+        var error: Unmanaged<CFError>?
+        let accessControl = SecAccessControlCreateWithFlags(nil, protection, flags, &error)
+        if let error = error?.takeRetainedValue() {
+            print("Error creating access control: \(error.localizedDescription)")
+            return nil
+        }
+        return accessControl
+    }
 
     /// Constructs a keychain query dictionary from the given parameters.
     private func baseQuery(from params: KeychainQueryParameters) -> [CFString: Any] {
@@ -108,14 +154,6 @@ class FlutterSecureStorage {
             query[kSecAttrService] = service
         }
 
-        if let isSynchronizable = params.isSynchronizable {
-            query[kSecAttrSynchronizable] = isSynchronizable
-        }
-
-        if let accessibilityLevel = params.accessibilityLevel {
-            query[kSecAttrAccessible] = parseAccessibleAttr(accessibilityLevel)
-        }
-
         if let shouldReturnData = params.shouldReturnData {
             query[kSecReturnData] = shouldReturnData
         }
@@ -152,8 +190,15 @@ class FlutterSecureStorage {
             query[kSecUseAuthenticationUI] = authenticationUIBehavior
         }
 
-        if let accessControlSettings = params.accessControlSettings {
-            query[kSecAttrAccessControl] = accessControlSettings
+        if let accessControl = createAccessControl(params: params) {
+            query[kSecAttrAccessControl] = accessControl
+        } else {
+            if let accessibilityLevel = params.accessibilityLevel {
+                query[kSecAttrAccessible] = parseAccessibleAttr(accessibilityLevel)
+            }
+            if let isSynchronizable = params.isSynchronizable {
+                query[kSecAttrSynchronizable] = isSynchronizable
+            }
         }
 
         #if os(macOS)
@@ -172,11 +217,6 @@ class FlutterSecureStorage {
     }
 
     private func validateQueryParameters(params: KeychainQueryParameters) throws {
-        // Accessibility and access control
-        if params.accessibilityLevel != nil, params.accessControlSettings != nil {
-            throw OSSecError(status: errSecParam, message: "Cannot use kSecAttrAccessible and kSecAttrAccessControl together.")
-        }
-
         // Match limit
         if params.resultLimit == 1, params.shouldReturnData == true {
             throw OSSecError(status: errSecParam, message: "Cannot use kSecMatchLimitAll when expecting a single result with kSecReturnData.")

flutter_secure_storage_darwin/darwin/flutter_secure_storage_darwin/Sources/flutter_secure_storage_darwin/FlutterSecureStorageDarwinPlugin.swift

@@ -164,7 +164,8 @@ public class FlutterSecureStorageDarwinPlugin: NSObject, FlutterPlugin, FlutterS
             isHidden: (options["isHidden"] as? String).flatMap { Bool($0) },
             isPlaceholder: (options["isPlaceholder"] as? String).flatMap { Bool($0) },
             shouldReturnPersistentReference: (options["persistentReference"] as? String).flatMap { Bool($0) },
-            authenticationUIBehavior: options["authenticationUIBehavior"] as? String
+            authenticationUIBehavior: options["authenticationUIBehavior"] as? String,
+            accessControlFlags: options["accessControlFlags"] as? String
         )
 
         return (parameters, value)