Add support for Yubikey command chaining
This commit is contained in:
Anton Krasovsky
Mingshen Sun
parent
e6c9440bff
commit
f6b2316324
3 changed files with 204 additions and 100 deletions
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@ -526,11 +526,12 @@ class PasswordDetailTableViewController: UITableViewController, UIGestureRecogni
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}
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extension PasswordDetailTableViewController {
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private func requestYubiKeyPIN(completion: @escaping (String) -> Void) {
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private func requestYubiKeyPIN(completion: @escaping (String) -> Void, cancellation: @escaping () -> Void) {
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let alert = UIAlertController(title: "YubiKey PIN", message: "Verify YubiKey OpenPGP PIN.", preferredStyle: .alert)
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alert.addAction(
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UIAlertAction.cancel { _ in
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self.navigationController!.popViewController(animated: true)
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cancellation()
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}
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)
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alert.addAction(
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@ -570,7 +571,7 @@ extension PasswordDetailTableViewController {
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}
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}
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private func handleCancellation(_: Error) {
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private func handleCancellation() {
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DispatchQueue.main.async {
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self.navigationController?.popViewController(animated: true)
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}
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@ -55,7 +55,7 @@ func decryptPassword(
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}
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}
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public typealias RequestPINAction = (@escaping (String) -> Void) -> Void
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public typealias RequestPINAction = (@escaping (String) -> Void, @escaping () -> Void) -> Void
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let symmetricKeyIDNameDict: [UInt8: String] = [
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2: "3des",
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@ -66,124 +66,194 @@ let symmetricKeyIDNameDict: [UInt8: String] = [
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]
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private func isEncryptKeyAlgoRSA(_ applicationRelatedData: Data) -> Bool {
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if #available(iOS 13.0, *) {
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let tlv = TKBERTLVRecord.sequenceOfRecords(from: applicationRelatedData)!
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// 0x73: Discretionary data objects
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for record in TKBERTLVRecord.sequenceOfRecords(from: tlv.first!.value)! where record.tag == 0x73 {
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// 0xC2: Algorithm attributes decryption, 0x01: RSA
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for record2 in TKBERTLVRecord.sequenceOfRecords(from: record.value)! where record2.tag == 0xC2 && record2.value.first! == 0x01 {
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return true
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}
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let tlv = TKBERTLVRecord.sequenceOfRecords(from: applicationRelatedData)!
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// 0x73: Discretionary data objects
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for record in TKBERTLVRecord.sequenceOfRecords(from: tlv.first!.value)! where record.tag == 0x73 {
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// 0xC2: Algorithm attributes decryption, 0x01: RSA
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for record2 in TKBERTLVRecord.sequenceOfRecords(from: record.value)! where record2.tag == 0xC2 && record2.value.first! == 0x01 {
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return true
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}
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return false
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} else {
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// We need CryptoTokenKit (iOS 13.0+) to check if data is RSA, so fail open here.
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return true
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}
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return false
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}
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private func getCapabilities(_ applicationRelatedData: Data) -> (Bool, Bool) {
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let tlv = TKBERTLVRecord.sequenceOfRecords(from: applicationRelatedData)!
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// 0x5f52: Historical Bytes
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for record in TKBERTLVRecord.sequenceOfRecords(from: tlv.first!.value)! where record.tag == 0x5F52 {
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let historical = record.value
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if historical.count < 4 {
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// log_error ("warning: historical bytes are too short\n");
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return (false, false)
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}
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if historical[0] != 0 {
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// log_error ("warning: bad category indicator in historical bytes\n");
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return (false, false)
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}
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let dos = historical[1 ..< historical.endIndex - 3]
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for record2 in TKCompactTLVRecord.sequenceOfRecords(from: dos)! where record2.tag == 7 && record2.value.count == 3 {
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let cmd_chaining = (record2.value[2] & 0x80) != 0
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let ext_lc_le = (record2.value[2] & 0x40) != 0
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return (cmd_chaining, ext_lc_le)
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}
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}
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return (false, false)
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}
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// swiftlint:disable cyclomatic_complexity
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public func yubiKeyDecrypt(
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passwordEntity: PasswordEntity,
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requestPIN: @escaping RequestPINAction,
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errorHandler: @escaping ((AppError) -> Void),
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cancellation: @escaping ((_ error: Error) -> Void),
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cancellation: @escaping (() -> Void),
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completion: @escaping ((Password) -> Void)
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) {
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let encryptedDataPath = PasswordStore.shared.storeURL.appendingPathComponent(passwordEntity.getPath())
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Task {
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do {
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let encryptedDataPath = PasswordStore.shared.storeURL.appendingPathComponent(passwordEntity.getPath())
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guard let encryptedData = try? Data(contentsOf: encryptedDataPath) else {
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errorHandler(AppError.other(message: "PasswordDoesNotExist".localize()))
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return
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}
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// swiftlint:disable closure_body_length
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requestPIN { pin in
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// swiftlint:disable closure_body_length
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passKit.YubiKeyConnection.shared.connection(cancellation: cancellation) { connection in
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guard let smartCard = connection.smartCardInterface else {
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errorHandler(AppError.yubiKey(.connection(message: "Failed to get smart card interface.")))
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guard let encryptedData = try? Data(contentsOf: encryptedDataPath) else {
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errorHandler(AppError.other(message: "PasswordDoesNotExist".localize()))
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return
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}
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// 1. Select OpenPGP application
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let selectOpenPGPAPDU = YubiKeyAPDU.selectOpenPGPApplication()
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smartCard.selectApplication(selectOpenPGPAPDU) { _, error in
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guard error == nil else {
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errorHandler(AppError.yubiKey(.selectApplication(message: "Failed to select application.")))
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return
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}
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guard let pin = await readPin(requestPIN: requestPIN) else {
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return
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}
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// 2. Verify PIN
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let verifyApdu = YubiKeyAPDU.verify(password: pin)
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smartCard.executeCommand(verifyApdu) { _, error in
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guard error == nil else {
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errorHandler(AppError.yubiKey(.verify(message: "Failed to verify PIN.")))
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return
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}
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guard let connection = try? await getConnection() else {
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cancellation()
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return
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}
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let applicationRelatedDataApdu = YubiKeyAPDU.get_application_related_data()
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smartCard.executeCommand(applicationRelatedDataApdu) { data, _ in
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guard let data = data else {
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errorHandler(AppError.yubiKey(.decipher(message: "Failed to get application related data.")))
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return
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}
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guard let smartCard = connection.smartCardInterface else {
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throw AppError.yubiKey(.connection(message: "Failed to get smart card interface."))
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}
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if !isEncryptKeyAlgoRSA(data) {
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errorHandler(AppError.yubiKey(.decipher(message: "Encryption key algorithm is not supported. Supported algorithm: RSA.")))
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return
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}
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try await selectOpenPGPApplication(smartCard: smartCard)
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// 3. Decipher
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let ciphertext = encryptedData
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var error: NSError?
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let message = CryptoNewPGPMessage(ciphertext)
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guard let mpi1 = Gopenpgp.HelperPassGetEncryptedMPI1(message, &error) else {
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errorHandler(AppError.yubiKey(.decipher(message: "Failed to get encrypted MPI.")))
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return
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}
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try await verifyPin(smartCard: smartCard, pin: pin)
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let decipherApdu = YubiKeyAPDU.decipher(data: mpi1)
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smartCard.executeCommand(decipherApdu) { data, error in
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guard let data = data else {
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errorHandler(AppError.yubiKey(.decipher(message: "Failed to execute decipher.")))
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return
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}
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guard let applicationRelatedData = try await getApplicationRelatedData(smartCard: smartCard) else {
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throw AppError.yubiKey(.decipher(message: "Failed to get application related data."))
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}
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if #available(iOS 13.0, *) {
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YubiKitManager.shared.stopNFCConnection()
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}
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guard let algoByte = data.first, let algo = symmetricKeyIDNameDict[algoByte] else {
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errorHandler(AppError.yubiKey(.decipher(message: "Failed to new session key.")))
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return
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}
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guard let session_key = Gopenpgp.CryptoNewSessionKeyFromToken(data[1 ..< data.count - 2], algo) else {
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errorHandler(AppError.yubiKey(.decipher(message: "Failed to new session key.")))
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return
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}
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if !isEncryptKeyAlgoRSA(applicationRelatedData) {
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throw AppError.yubiKey(.decipher(message: "Encryption key algorithm is not supported. Supported algorithm: RSA."))
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}
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var error: NSError?
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let message = CryptoNewPGPMessage(ciphertext)
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let (cmd_chaining, _) = getCapabilities(applicationRelatedData)
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guard let plaintext = Gopenpgp.HelperPassDecryptWithSessionKey(message, session_key, &error)?.data else {
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errorHandler(AppError.yubiKey(.decipher(message: "Failed to decrypt with session key.")))
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return
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}
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let deciphered = try await decipher(smartCard: smartCard, ciphertext: encryptedData, chained: cmd_chaining)
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guard let plaintext_str = String(data: plaintext, encoding: .utf8) else {
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errorHandler(AppError.yubiKey(.decipher(message: "Failed to convert plaintext to string.")))
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return
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}
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YubiKitManager.shared.stopNFCConnection()
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guard let password = try? Password(name: passwordEntity.getName(), url: passwordEntity.getURL(), plainText: plaintext_str) else {
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errorHandler(AppError.yubiKey(.decipher(message: "Failed to construct password.")))
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return
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}
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let plaintext = try decryptPassword(deciphered: deciphered, ciphertext: encryptedData)
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guard let password = try? Password(name: passwordEntity.getName(), url: passwordEntity.getURL(), plainText: plaintext) else {
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throw AppError.yubiKey(.decipher(message: "Failed to construct password."))
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}
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completion(password)
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}
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}
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}
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completion(password)
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} catch let error as AppError {
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errorHandler(error)
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} catch {
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errorHandler(AppError.other(message: String(describing: error)))
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}
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}
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}
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func readPin(requestPIN: @escaping RequestPINAction) async -> String? {
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await withCheckedContinuation { (continuation: CheckedContinuation<String?, Never>) in
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DispatchQueue.main.async {
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requestPIN({ pin in continuation.resume(returning: pin) }, { continuation.resume(returning: nil) })
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}
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}
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}
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func getConnection() async throws -> YKFConnectionProtocol? {
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try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<YKFConnectionProtocol?, Error>) in
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passKit.YubiKeyConnection.shared.connection(cancellation: { error in
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continuation.resume(throwing: error)
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}, completion: { connection in
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continuation.resume(returning: connection)
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})
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}
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}
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func selectOpenPGPApplication(smartCard: YKFSmartCardInterface) async throws {
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if await withCheckedContinuation({ (continuation: CheckedContinuation<Error?, Never>) in
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smartCard.selectApplication(YubiKeyAPDU.selectOpenPGPApplication()) { _, error in
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continuation.resume(returning: error)
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}
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}) != nil {
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throw AppError.yubiKey(.selectApplication(message: "Failed to select application."))
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}
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}
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func getApplicationRelatedData(smartCard: YKFSmartCardInterface) async throws -> Data? {
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try await executeCommandAsync(smartCard: smartCard, apdu: YubiKeyAPDU.get_application_related_data())
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}
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func verifyPin(smartCard: YKFSmartCardInterface, pin: String) async throws {
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if await withCheckedContinuation({ (continuation: CheckedContinuation<Error?, Never>) in
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smartCard.executeCommand(YubiKeyAPDU.verify(password: pin)) { _, error in
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continuation.resume(returning: error)
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}}) != nil {
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throw AppError.yubiKey(.selectApplication(message: "Failed to verify PIN."))
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}
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}
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func decipher(smartCard: YKFSmartCardInterface, ciphertext: Data, chained: Bool) async throws -> Data {
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var error: NSError?
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let message = CryptoNewPGPMessage(ciphertext)
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guard let mpi1 = Gopenpgp.HelperPassGetEncryptedMPI1(message, &error) else {
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throw AppError.yubiKey(.decipher(message: "Failed to get encrypted MPI."))
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}
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let apdus = chained ? YubiKeyAPDU.decipherChained(data: mpi1) : YubiKeyAPDU.decipherExtended(data: mpi1)
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for (idx, apdu) in apdus.enumerated() {
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let data = try await executeCommandAsync(smartCard: smartCard, apdu: apdu)
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// the last response must have the data
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if idx == apdus.endIndex - 1, let data {
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return data
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}
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}
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throw AppError.yubiKey(.verify(message: "Failed to execute decipher."))
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}
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func decryptPassword(deciphered: Data, ciphertext: Data) throws -> String {
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let message = CryptoNewPGPMessage(ciphertext)
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guard let algoByte = deciphered.first, let algo = symmetricKeyIDNameDict[algoByte] else {
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throw AppError.yubiKey(.decipher(message: "Failed to new session key."))
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}
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guard let session_key = Gopenpgp.CryptoNewSessionKeyFromToken(deciphered[1 ..< deciphered.count - 2], algo) else {
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throw AppError.yubiKey(.decipher(message: "Failed to new session key."))
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}
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var error: NSError?
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guard let plaintext = Gopenpgp.HelperPassDecryptWithSessionKey(message, session_key, &error)?.data else {
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throw AppError.yubiKey(.decipher(message: "Failed to decrypt with session key: \(String(describing: error))"))
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}
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guard let plaintext_str = String(data: plaintext, encoding: .utf8) else {
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throw AppError.yubiKey(.decipher(message: "Failed to convert plaintext to string."))
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}
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return plaintext_str
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}
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func executeCommandAsync(smartCard: YKFSmartCardInterface, apdu: YKFAPDU) async throws -> Data? {
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try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Data?, Error>) in
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smartCard.executeCommand(apdu) { data, error in
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if let error {
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continuation.resume(throwing: error)
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} else {
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continuation.resume(returning: data)
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}
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}
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}
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@ -26,9 +26,9 @@ public enum YubiKeyAPDU {
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return verifyApdu
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}
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public static func decipher(data: Data) -> YKFAPDU {
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public static func decipherExtended(data: Data) -> [YKFAPDU] {
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var apdu: [UInt8] = []
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apdu += [0x00] // CLA
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apdu += [0x00] // CLA (last or only command of a chain)
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apdu += [0x2A, 0x80, 0x86] // INS, P1, P2: PSO.DECIPHER
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// Lc, An extended Lc field consists of three bytes:
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// one byte set to '00' followed by two bytes not set to '0000' (1 to 65535 dec.).
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@ -37,9 +37,32 @@ public enum YubiKeyAPDU {
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apdu += [0x00]
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apdu += data
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apdu += [0x02, 0x00]
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let decipherApdu = YKFAPDU(data: Data(apdu))!
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return decipherApdu
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return [YKFAPDU(data: Data(apdu))!]
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}
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public static func decipherChained(data: Data) -> [YKFAPDU] {
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var result: [YKFAPDU] = []
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let chunks = chunk(data: data)
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for chunk in chunks.dropLast() {
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var apdu: [UInt8] = []
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apdu += [0x10] // CLA (command is not the last command of a chain)
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apdu += [0x2A, 0x80, 0x86] // INS, P1, P2: PSO.DECIPHER
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apdu += withUnsafeBytes(of: UInt8(chunk.count).bigEndian, Array.init)
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apdu += chunk
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result += [YKFAPDU(data: Data(apdu))!]
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}
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var apdu: [UInt8] = []
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apdu += [0x00] // CLA (last or only command of a chain)
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apdu += [0x2A, 0x80, 0x86] // INS, P1, P2: PSO.DECIPHER
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apdu += withUnsafeBytes(of: UInt8(chunks.last!.count).bigEndian, Array.init)
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apdu += chunks.last!
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apdu += [0x00] // Le
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result += [YKFAPDU(data: Data(apdu))!]
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return result
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}
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public static func get_application_related_data() -> YKFAPDU {
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@ -51,4 +74,14 @@ public enum YubiKeyAPDU {
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apdu += [0x00]
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return YKFAPDU(data: Data(apdu))!
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}
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static func chunk(data: Data) -> [[UInt8]] {
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// starts with 00 padding
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let padded: [UInt8] = [0x00] + data
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let MAX_SIZE = 254
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return stride(from: 0, to: padded.count, by: MAX_SIZE).map {
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Array(padded[$0 ..< Swift.min($0 + MAX_SIZE, padded.count)])
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}
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}
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}
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