initial commit

KeychainStore.swift

@@ -0,0 +1,54 @@
+import Foundation
+import Security
+
+/// Minimal Keychain wrapper for storing the MCMS credentials. Stores the
+/// password (and optionally host/email) keyed by a service + account. Never
+/// use UserDefaults for secrets.
+struct KeychainStore {
+
+    let service: String
+
+    init(service: String = "com.example.mcmsmobile.credentials") {
+        self.service = service
+    }
+
+    @discardableResult
+    func set(_ value: String, account: String) -> Bool {
+        guard let data = value.data(using: .utf8) else { return false }
+        let query: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrService as String: service,
+            kSecAttrAccount as String: account
+        ]
+        SecItemDelete(query as CFDictionary)
+
+        var attributes = query
+        attributes[kSecValueData as String] = data
+        attributes[kSecAttrAccessible as String] = kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly
+        return SecItemAdd(attributes as CFDictionary, nil) == errSecSuccess
+    }
+
+    func get(account: String) -> String? {
+        let query: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrService as String: service,
+            kSecAttrAccount as String: account,
+            kSecReturnData as String: true,
+            kSecMatchLimit as String: kSecMatchLimitOne
+        ]
+        var item: CFTypeRef?
+        guard SecItemCopyMatching(query as CFDictionary, &item) == errSecSuccess,
+              let data = item as? Data else { return nil }
+        return String(data: data, encoding: .utf8)
+    }
+
+    @discardableResult
+    func delete(account: String) -> Bool {
+        let query: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrService as String: service,
+            kSecAttrAccount as String: account
+        ]
+        return SecItemDelete(query as CFDictionary) == errSecSuccess
+    }
+}