Secure Settings store (#831)

* Add SettingsStore

* Use keychain instead of UserDefaults in JustUpdatedChecker.swift

* Add ability disable the SSH comment via settings

* Make SettingsStore functions non-static, re-implement them as
subscripts and make settingsStore an environmentObject

Fixes: https://github.com/maxgoedjen/secretive/pull/536#discussion_r1508446459

* Add rawValues for CommentStyle enum

* Use SettingsStore for querying the comment style in SecretDetailView

Fixes: https://github.com/maxgoedjen/secretive/pull/536#discussion_r1509655340

* Revert "Use keychain instead of UserDefaults in JustUpdatedChecker.swift"

This reverts commit ae8a21a1bf7f9e2d04fcb83c4543995db0111325.

* Remove copyright info

* Use "enum Constants" in SettingsStore

* WIP

* Cleanup

* Cleanup

* Cleanup strings

* WIP

* Cleanup

* Cleanup

* Cleanup

* Cleanup

* Cleanup

---------

Co-authored-by: Paul Heidekrüger <paul.heidekrueger@tum.de>

Sources/Packages/Package.swift

@@ -22,6 +22,9 @@ let package = Package(
         .library(
             name: "CertificateKit",
             targets: ["CertificateKit"]),
+        .library(
+            name: "SettingsKit",
+            targets: ["SettingsKit"]),
         .library(
             name: "SecretAgentKit",
             targets: ["SecretAgentKit"]),
@@ -76,6 +79,12 @@ let package = Package(
             resources: [localization],
             swiftSettings: swiftSettings,
         ),
+        .target(
+            name: "SettingsKit",
+            dependencies: [],
+            resources: [localization],
+            swiftSettings: swiftSettings,
+        ),
         .target(
             name: "SecretAgentKit",
             dependencies: ["SecretKit", "SSHProtocolKit", "CertificateKit", "Common", "Formatters"],

Sources/Packages/Sources/SettingsKit/SettingKeys.swift

@@ -0,0 +1,14 @@
+import Foundation
+
+struct RequireDestinationInformationSettingsKey: SettingsStore.SettingsKey {
+    static let defaultValue: Bool = true
+}
+
+extension SettingsStore {
+
+    public var requireDestinationInformation: Bool {
+        get { self[RequireDestinationInformationSettingsKey.self] }
+        set { self[RequireDestinationInformationSettingsKey.self] = newValue }
+    }
+
+}

Sources/Packages/Sources/SettingsKit/SettingsStore.swift

@@ -0,0 +1,114 @@
+import Foundation
+import Observation
+import Security
+import OSLog
+
+// Setting store backed by macOS keychain for stronger guarantees around ownership/other-process-modification than UserDefaults offers.
+@Observable @MainActor public final class SettingsStore: Sendable {
+
+    private let logger = Logger(subsystem: "com.maxgoedjen.secretive.settings", category: "SettingsStore")
+
+    public init() {
+    }
+
+    private var state: [ObjectIdentifier: UUID] = [:]
+
+    subscript<SettingsKeyType: SettingsKey>(_ key: SettingsKeyType.Type) -> SettingsKeyType.Value {
+        get {
+            _ = state[ObjectIdentifier(key)]
+            let queryAttributes = KeychainDictionary([
+                kSecClass: Constants.keyClass,
+                kSecAttrService: Constants.keyTag,
+                kSecAttrAccount: String(describing: SettingsKeyType.self),
+                kSecUseDataProtectionKeychain: true,
+                kSecReturnData: true,
+                kSecReturnAttributes: true,
+                kSecMatchLimit: kSecMatchLimitOne,
+                ])
+            var untyped: CFTypeRef?
+            unsafe SecItemCopyMatching(queryAttributes, &untyped)
+            guard let typed = untyped as? [CFString: Any] else { return SettingsKeyType.defaultValue }
+            let decoder = JSONDecoder()
+            guard let data = typed[kSecValueData] as? Data else { return SettingsKeyType.defaultValue }
+            return (try? decoder.decode(SettingValue<SettingsKeyType.Value>.self, from: data).value) ?? SettingsKeyType.defaultValue
+        }
+        set {
+            do {
+                let data = try JSONEncoder().encode(SettingValue(value: newValue))
+                let keychainAttributes = KeychainDictionary([
+                    kSecClass: Constants.keyClass,
+                    kSecAttrService: Constants.keyTag,
+                    kSecAttrAccount: String(describing: SettingsKeyType.self),
+                    kSecUseDataProtectionKeychain: true,
+                    kSecAttrAccessible: kSecAttrAccessibleWhenUnlockedThisDeviceOnly,
+                    kSecValueData: data,
+                ])
+                let status = SecItemAdd(keychainAttributes, nil)
+                switch status {
+                case errSecSuccess:
+                    break
+                case errSecDuplicateItem:
+                    let updateQuery = KeychainDictionary([
+                        kSecClass: Constants.keyClass,
+                        kSecAttrService: Constants.keyTag,
+                        kSecAttrAccount: String(describing: SettingsKeyType.self),
+                    ])
+                    let updatedAttributes = KeychainDictionary([
+                        kSecValueData: data,
+                    ])
+                    let status = SecItemUpdate(updateQuery, updatedAttributes)
+                    if status != errSecSuccess {
+                        throw KeychainError(statusCode: status)
+                    }
+                default:
+                    throw KeychainError(statusCode: status)
+                }
+                state[ObjectIdentifier(key)] = UUID()
+            } catch {
+                logger.error("Error updating key: \(String(describing: SettingsKeyType.self), privacy: .public): \(error.localizedDescription.debugDescription, privacy: .public)")
+            }
+        }
+    }
+
+
+}
+
+extension SettingsStore {
+
+    public protocol SettingsKey<Value>: Equatable, Codable, Sendable {
+        associatedtype Value: Codable
+        static var defaultValue: Value { get }
+    }
+
+}
+
+extension SettingsStore {
+
+    struct SettingValue<Value: Codable>: Codable {
+        let value: Value
+    }
+
+}
+
+
+extension SettingsStore {
+
+    fileprivate struct KeychainError: Error {
+        let statusCode: OSStatus?
+    }
+
+}
+
+fileprivate func KeychainDictionary(_ dictionary: [CFString: Any]) -> CFDictionary {
+    dictionary as CFDictionary
+}
+
+
+extension SettingsStore {
+
+    enum Constants {
+        static let keyClass = kSecClassGenericPassword as String
+        static let keyTag = "com.maxgoedjen.settingsStore"
+    }
+
+}