Streamline local authorization flows

4:58 - LAContext (authorize a signature operation 1)

let query: [String: Any] = [
    kSecClass as String: kSecClassKey,
    kSecAttrTokenID as String: kSecAttrTokenIDSecureEnclave,
    kSecAttrApplicationTag as String: "com.example.app.key",
    kSecReturnAttributes as String: true,
]

var item: CFTypeRef? = nil
guard SecItemCopyMatching(query as CFDictionary, &item) == errSecSuccess, let attrs = item as? NSDictionary, let accessControl = attrs[kSecAttrAccessControl] else {
    throw .aclNotFound
}

5:15 - LAContext (authorize a signature operation 2)

let context = LAContext()
try await context.evaluateAccessControl(accessControl as! SecAccessControl, 
                      operation: .useKeySign, 
                       localizedReason: "Authentication is required to proceed")

5:44 - LAContext (authorize a signature operation 3)

let query: [String: Any] = [
    kSecClass as String: kSecClassKey,
    kSecAttrTokenID as String: kSecAttrTokenIDSecureEnclave,
    kSecAttrApplicationTag as String: "com.example.app.key",
    kSecReturnRef as String: true,
    kSecUseAuthenticationContext as String: context
]

var item: CFTypeRef? = nil
guard SecItemCopyMatching(query as CFDictionary, &item) == errSecSuccess, item != nil else { 
    throw .keyNotFound
}

6:00 - LAContext (authorize a signature operation 4)

let privateKey = item as! SecKey

var error: Unmanaged<CFError>?
guard let sgt = SecKeyCreateSignature(privateKey, self.algorithm, blob, &error) as Data? else {
    throw .signatureFailure
}

8:28 - LA Right (basic usage)

// LARight: Basic usage

func login() async {
   self.loginRight = LARight(requirement: .biometry(fallback: .devicePasscode))
   do {
       try await loginRight.checkCanAuthorize()
   } catch {
       navigateTo(section: .public)
       return
   }
   do {
      try await self.loginRight.authorize(localizedReason: self.localizedReason)
 navigateTo(section: .protected)
   } catch {
      showError(.authenticationRequired)
   }
}

11:01 - LARight (logout and deauthorization)

// LARight: Basic usage

func login() async {
   self.loginRight = LARight(requirement: .biometry(fallback: .devicePasscode))
   // ...
   do {
       try await self.loginRight.authorize(localizedReason: self.localizedReason)
  navigateTo(section: .protected)
   } catch {
       showError(.authenticationRequired)
   }
}

func logout() async {   
   await self.loginRight.deauthorize()
}

13:44 - LAPersistedRight

// LAPersistedRight: Retrieval and private key usage

func generateClientKeys() async throws -> Data {
    let login2FA = LARight(requirement: .biometryCurrentSet)
    let persisted2FA = try await LARightStore.shared.saveRight(login2FA, identifier: "2fa")
    return try await persisted2FA.key.publicKey.bytes
}

func signChallenge(_ challenge: Data, algorithm: SecKeyAlgorithm) async throws -> Data {
    let persisted2FA = try await LARightStore.shared.right(forIdentifier: "2fa")
    let localizedReason = "Biometric authentication is required to proceed"
    try await persisted2FA.authorize(localizedReason: localizedReason)
    return try await persisted2FA.key.sign(challenge, algorithm: algorithm)
}