PhantomKeychain

A tiny, type-safe Keychain wrapper for Swift. Store secrets behind phantom-typed keys so the compiler — not you — keeps track of what type lives at each key.

Why

The Keychain API is stringly-typed: you write Data, you read Data, and you're left to remember what was supposed to live at each key. PhantomKeychain gives you KeychainKey<Value> — a key that carries its value's type at compile time:

let token = KeychainKey<String>(name: "auth_token")

store.set("abc", forKey: token)              // ✅ String in
let value: String? = store.get(forKey: token) // ✅ String out, no casting
store.set(true, forKey: token)               // ❌ won't compile — `token` is a String key

Install

Swift Package Manager — add the dependency to your Package.swift:

.package(url: "https://github.com/hamsternik/PhantomKeychain.git", from: "0.1.0"),

then add PhantomKeychain to your target:

.product(name: "PhantomKeychain", package: "PhantomKeychain"),

Usage

import PhantomKeychain

let store: KeychainStore = KeychainStoreLive(keyPrefix: "com.yourapp.")

let apiToken = KeychainKey<String>(name: "api_token")

store.set("s3cr3t", forKey: apiToken)     // -> Bool
let token = store.get(forKey: apiToken)   // -> String?
store.remove(by: apiToken)                // -> Bool
store.clear()                             // wipe everything under the prefix

String, Data, and Bool are storable out of the box. Conform your own types to KeychainStorable (a var keychainData: Data getter plus an init?(keychainData:)) to store them too.

Testing

Swap in KeychainStoreInMemory — a thread-safe, Keychain-free double with identical behavior — so your tests never touch the system Keychain:

let store: KeychainStore = KeychainStoreInMemory()

Details

• Access: items use kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly — readable after first unlock, never synced to iCloud or restored to another device.
• Prefix: keys are namespaced by keyPrefix. Pass your own to isolate your app's items from anything else in the Keychain.
• Backing: 0.1.0 is built on KeychainSwift. 0.2.0 will drop it for a zero-dependency Security/SecItem implementation — with the same public API.

Roadmap

• Publish a GitHub Release with notes for 0.2.0 (skipped for 0.1.0).
• Register the package on Swift Package Index for discoverability.
• Add an example project demonstrating real-world integration of the library in an app.
• Expand CI to a full test matrix across every supported platform/OS/device (currently only swift test on the macOS host). Reference: KeychainAccess test.yml — matrix over macOS runners × Xcode versions × simulator OS versions × device models, with xcodebuild test per destination.

Requirements

• Swift 5.9+
• iOS 16+ · macOS 13+ · watchOS 9+

License

MIT © 2026 Mykyta Khomitsevych