feat: add KeychainStore

MyPassCore/Sources/MyPassCore/Keychain/KeychainError.swift

@@ -0,0 +1,7 @@
+import Foundation
+
+public enum KeychainError: Error, Equatable {
+    case saveFailed(OSStatus)
+    case loadFailed(OSStatus)
+    case notFound
+}

MyPassCore/Sources/MyPassCore/Keychain/KeychainStore.swift

@@ -0,0 +1,68 @@
+import Foundation
+import Security
+
+public struct KeychainStore {
+    private let accessGroup: String
+    private let service: String
+
+    public init(accessGroup: String, service: String = "com.christophevila.mypass") {
+        self.accessGroup = accessGroup
+        self.service = service
+    }
+
+    public func save(password: String, for account: String) throws {
+        let data = Data(password.utf8)
+        let query: [CFString: Any] = [
+            kSecClass:           kSecClassGenericPassword,
+            kSecAttrService:     service,
+            kSecAttrAccount:     account,
+            kSecAttrAccessGroup: accessGroup,
+            kSecAttrAccessible:  kSecAttrAccessibleWhenUnlockedThisDeviceOnly,
+            kSecValueData:       data,
+        ]
+        SecItemDelete(query as CFDictionary)
+        let status = SecItemAdd(query as CFDictionary, nil)
+        guard status == errSecSuccess else { throw KeychainError.saveFailed(status) }
+    }
+
+    public func load(for account: String) throws -> String {
+        let query: [CFString: Any] = [
+            kSecClass:           kSecClassGenericPassword,
+            kSecAttrService:     service,
+            kSecAttrAccount:     account,
+            kSecAttrAccessGroup: accessGroup,
+            kSecReturnData:      true,
+            kSecMatchLimit:      kSecMatchLimitOne,
+        ]
+        var result: AnyObject?
+        let status = SecItemCopyMatching(query as CFDictionary, &result)
+        guard status == errSecSuccess else {
+            throw status == errSecItemNotFound ? KeychainError.notFound : KeychainError.loadFailed(status)
+        }
+        guard let data = result as? Data, let password = String(data: data, encoding: .utf8) else {
+            throw KeychainError.loadFailed(errSecInvalidData)
+        }
+        return password
+    }
+
+    public func delete(for account: String) {
+        let query: [CFString: Any] = [
+            kSecClass:           kSecClassGenericPassword,
+            kSecAttrService:     service,
+            kSecAttrAccount:     account,
+            kSecAttrAccessGroup: accessGroup,
+        ]
+        SecItemDelete(query as CFDictionary)
+    }
+
+    public func exists(for account: String) -> Bool {
+        let query: [CFString: Any] = [
+            kSecClass:           kSecClassGenericPassword,
+            kSecAttrService:     service,
+            kSecAttrAccount:     account,
+            kSecAttrAccessGroup: accessGroup,
+            kSecMatchLimit:      kSecMatchLimitOne,
+        ]
+        return SecItemCopyMatching(query as CFDictionary, nil) == errSecSuccess
+    }
+}