Helper functions for storing text in Keychain for iOS, macOS, tvOS and WatchOS

[][carthage] [][cocoadocs] [][cocoadocs] [][cocoadocs] [cocoadocs]: http://cocoadocs.org/docsets/KeychainSwift [carthage]: https://github.com/Carthage/Carthage

Important: KeychainSwift currently does not work at all on iOS 10 / Xcode 8. If you use Xcode 8 you will need to run your app in an iOS 9 simulator or device.

This is a collection of helper functions for saving text and data in the Keychain. As you probably noticed Apple's keychain API is a bit verbose. This library was designed to provide shorter syntax for accomplishing a simple task: reading/writing text values for specified keys:

let keychain = KeychainSwift()
keychain.set("hello world", forKey: "my key")
keychain.get("my key")

The Keychain library includes the following features:

• Get, set and delete string, boolean and Data Keychain items
• Specify item access security level
• Synchronize items through iCloud
• Share Keychain items with other apps

What's Keychain?

Keychain is a secure storage. You can store all kind of sensitive data in it: user passwords, credit card numbers, secret tokens etc. Once stored in Keychain this information is only available to your app, other apps can't see it. Besides that, operating system makes sure this information is kept and processed securely. For example, text stored in Keychain can not be extracted from iPhone backup or from its file system. Apple recommends storing only small amount of data in the Keychain. If you need to secure something big you can encrypt it manually, save to a file and store the key in the Keychain.

Setup (Swift 3.0)

There are three ways you can add KeychainSwift to your Xcode project.

Add source (iOS 7+)

Simply add KeychainSwiftDistrib.swift file into your Xcode project.

Setup with Carthage (iOS 8+)

Alternatively, add github "marketplacer/keychain-swift" ~> 4.0 to your Cartfile and run carthage update.

Setup with CocoaPods (iOS 8+)

If you are using CocoaPods add this text to your Podfile and run pod install.

use_frameworks!
target 'Your target name'
pod 'KeychainSwift', '~> 4.0'

Legacy Swift versions

Setup a previous version of the library if you use an older version of Swift.

iOS 7 support

Use iOS 7 compatible version of the library.

Usage

Add import KeychainSwift to your source code if you used Carthage or CocoaPods setup methods.

String values

let keychain = KeychainSwift()

keychain.set("hello world", forKey: "my key")

keychain.get("my key")

Boolean values

let keychain = KeychainSwift()

keychain.set(true, forKey: "my key")

keychain.getBool("my key")

Data values

let keychain = KeychainSwift()

keychain.set(dataObject, forKey: "my key")

keychain.getData("my key")

Removing keys from Keychain

keychain.delete("my key") // Remove single key

keychain.clear() // Delete everything from app's Keychain. Does not work on macOS.

Advanced options

Keychain item access

Use withAccess parameter to specify the security level of the keychain storage. By default the .accessibleWhenUnlocked option is used. It is one of the most restrictive options and provides good data protection.

KeychainSwift().set("Hello world", forKey: "key 1", withAccess: .accessibleWhenUnlocked)

You can use .accessibleAfterFirstUnlock if you need your app to access the keychain item while in the background. Note that it is less secure than the .accessibleWhenUnlocked option.

See the list of all available access options.

Synchronizing keychain items with other devices

Set synchronizable property to true to enable keychain items synchronization across user's multiple devices. The synchronization will work for users who have the "Keychain" enabled in the iCloud settings on their devices.

Setting synchronizable property to true will add the item to other devices with the set method and obtain synchronizable items with the get command. Deleting a synchronizable item will remove it from all devices.

Note that you do NOT need to enable iCloud or Keychain Sharing capabilities in your app's target for this feature to work.

// First device
let keychain = KeychainSwift()
keychain.synchronizable = true
keychain.set("hello world", forKey: "my key")

// Second device
let keychain = KeychainSwift()
keychain.synchronizable = true
keychain.get("my key") // Returns "hello world"

We could not get the Keychain synchronization work on macOS.

Sharing keychain items with other apps

In order to share keychain items between apps on the same device they need to have common Keychain Groups registered in Capabilities > Keychain Sharing settings. This tutorial shows how to set it up.

Use accessGroup property to access shared keychain items. In the following example we specify an access group "CS671JRA62.com.myapp.KeychainGroup" that will be used to set, get and delete an item "my key".

let keychain = KeychainSwift()
keychain.accessGroup = "CS671JRA62.com.myapp.KeychainGroup" // Use your own access goup

keychain.set("hello world", forKey: "my key")
keychain.get("my key")
keychain.delete("my key")
keychain.clear()

Note: there is no way of sharing a keychain item between the watchOS 2.0 and its paired device: https://forums.developer.apple.com/thread/5938

Setting key prefix

One can pass a keyPrefix argument when initializing a KeychainSwift object. The string passed in keyPrefix argument will be used as a prefix to all the keys used in set, get, getData and delete methods. I use the prefixed keychain in tests. This prevents the tests from changing the Keychain keys that are used when the app is launched manually.

Note that clear method still clears everything from the Keychain regardless of the prefix used.

let keychain = KeychainSwift(keyPrefix: "myTestKey_")
keychain.set("hello world", forKey: "hello")
// Value will be stored under "myTestKey_hello" key

Check if operation was successful

One can verify if set, delete and clear methods finished successfully by checking their return values. Those methods return true on success and false on error.

if keychain.set("hello world", forKey: "my key") {
  // Keychain item is saved successfully
} else {
  // Report error
}

To get a specific failure reason use the lastResultCode property containing result code for the last operation. See Keychain Services Result Codes.

keychain.set("hello world", forKey: "my key")
if keychain.lastResultCode != noErr { /* Report error */ }

Known serious issue

It has been reported that the library sometimes returns nil instead of the stored Keychain value. The issue seems to be random and hard to reproduce. It may be connected with the Keychain issue reported on Apple developer forums. If you experienced this problem feel free to create an issue so we can discuss it and find solutions.

Demo app

Alternative solutions

Here are some other Keychain libraries.

• DanielTomlinson/Latch
• jrendel/SwiftKeychainWrapper
• kishikawakatsumi/KeychainAccess
• matthewpalmer/Locksmith
• phuonglm86/SwiftyKey
• s-aska/KeyClip
• yankodimitrov/SwiftKeychain

Thanks 👍

• The code is based on this example: https://gist.github.com/s-aska/e7ad24175fb7b04f78e7
• Thanks to glyuck for taming booleans.
• Thanks to pepibumur for adding macOS, watchOS and tvOS support.
• Thanks to ezura for iOS 7 support.
• Thanks to mikaoj for adding keychain synchronization.
• Thanks to tcirwin for adding Swift 3.0 support.

License

Keychain Swift is released under the MIT License.