270 lines
11 KiB
Swift
270 lines
11 KiB
Swift
import Foundation
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import Combine
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import Security
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import CryptoTokenKit
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import LocalAuthentication
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import SecretKit
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extension SmartCard {
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/// An implementation of Store backed by a Smart Card.
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public class Store: SecretStore {
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@Published public var isAvailable: Bool = false
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public let id = UUID()
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public private(set) var name = NSLocalizedString("Smart Card", comment: "Smart Card")
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@Published public private(set) var secrets: [Secret] = []
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private let watcher = TKTokenWatcher()
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private var tokenID: String?
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/// Initializes a Store.
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public init() {
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tokenID = watcher.nonSecureEnclaveTokens.first
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watcher.setInsertionHandler { string in
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guard self.tokenID == nil else { return }
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guard !string.contains("setoken") else { return }
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self.tokenID = string
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self.reloadSecrets()
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self.watcher.addRemovalHandler(self.smartcardRemoved, forTokenID: string)
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}
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if let tokenID = tokenID {
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self.isAvailable = true
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self.watcher.addRemovalHandler(self.smartcardRemoved, forTokenID: tokenID)
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}
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loadSecrets()
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}
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// MARK: Public API
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public func create(name: String) throws {
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fatalError("Keys must be created on the smart card.")
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}
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public func delete(secret: Secret) throws {
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fatalError("Keys must be deleted on the smart card.")
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}
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public func sign(data: Data, with secret: Secret, for provenance: SigningRequestProvenance) throws -> Data {
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guard let tokenID = tokenID else { fatalError() }
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let context = LAContext()
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context.localizedReason = "sign a request from \"\(provenance.origin.displayName)\" using secret \"\(secret.name)\""
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context.localizedCancelTitle = "Deny"
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let attributes = KeychainDictionary([
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kSecClass: kSecClassKey,
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kSecAttrKeyClass: kSecAttrKeyClassPrivate,
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kSecAttrApplicationLabel: secret.id as CFData,
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kSecAttrTokenID: tokenID,
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kSecUseAuthenticationContext: context,
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kSecReturnRef: true
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])
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var untyped: CFTypeRef?
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let status = SecItemCopyMatching(attributes, &untyped)
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if status != errSecSuccess {
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throw KeychainError(statusCode: status)
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}
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guard let untypedSafe = untyped else {
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throw KeychainError(statusCode: errSecSuccess)
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}
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let key = untypedSafe as! SecKey
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var signError: SecurityError?
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guard let signature = SecKeyCreateSignature(key, signatureAlgorithm(for: secret, allowRSA: true), data as CFData, &signError) else {
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throw SigningError(error: signError)
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}
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return signature as Data
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}
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public func verify(signature: Data, for data: Data, with secret: Secret) throws -> Bool {
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let attributes = KeychainDictionary([
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kSecAttrKeyType: secret.algorithm.secAttrKeyType,
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kSecAttrKeySizeInBits: secret.keySize,
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kSecAttrKeyClass: kSecAttrKeyClassPublic
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])
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var verifyError: SecurityError?
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let untyped: CFTypeRef? = SecKeyCreateWithData(secret.publicKey as CFData, attributes, &verifyError)
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guard let untypedSafe = untyped else {
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throw KeychainError(statusCode: errSecSuccess)
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}
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let key = untypedSafe as! SecKey
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let verified = SecKeyVerifySignature(key, signatureAlgorithm(for: secret, allowRSA: true), data as CFData, signature as CFData, &verifyError)
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if !verified, let verifyError {
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if verifyError.takeUnretainedValue() ~= .verifyError {
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return false
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} else {
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throw SigningError(error: verifyError)
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}
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}
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return verified
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}
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public func existingPersistedAuthenticationContext(secret: Secret) -> PersistedAuthenticationContext? {
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nil
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}
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public func persistAuthentication(secret: Secret, forDuration: TimeInterval) throws {
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}
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/// Reloads all secrets from the store.
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public func reloadSecrets() {
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DispatchQueue.main.async {
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self.isAvailable = self.tokenID != nil
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let before = self.secrets
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self.secrets.removeAll()
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self.loadSecrets()
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if self.secrets != before {
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NotificationCenter.default.post(name: .secretStoreReloaded, object: self)
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}
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}
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}
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}
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}
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extension SmartCard.Store {
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/// Resets the token ID and reloads secrets.
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/// - Parameter tokenID: The ID of the token that was removed.
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private func smartcardRemoved(for tokenID: String? = nil) {
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self.tokenID = nil
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reloadSecrets()
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}
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/// Loads all secrets from the store.
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private func loadSecrets() {
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guard let tokenID = tokenID else { return }
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let fallbackName = NSLocalizedString("Smart Card", comment: "Smart Card")
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if #available(macOS 12.0, *) {
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if let driverName = watcher.tokenInfo(forTokenID: tokenID)?.driverName {
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name = driverName
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} else {
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name = fallbackName
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}
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} else {
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// Hack to read name if there's only one smart card
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let slotNames = TKSmartCardSlotManager().slotNames
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if watcher.nonSecureEnclaveTokens.count == 1 && slotNames.count == 1 {
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name = slotNames.first!
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} else {
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name = fallbackName
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}
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}
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let attributes = KeychainDictionary([
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kSecClass: kSecClassKey,
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kSecAttrTokenID: tokenID,
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kSecReturnRef: true,
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kSecMatchLimit: kSecMatchLimitAll,
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kSecReturnAttributes: true
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])
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var untyped: CFTypeRef?
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SecItemCopyMatching(attributes, &untyped)
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guard let typed = untyped as? [[CFString: Any]] else { return }
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let wrapped = typed.map {
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let name = $0[kSecAttrLabel] as? String ?? "Unnamed"
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let tokenID = $0[kSecAttrApplicationLabel] as! Data
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let algorithm = Algorithm(secAttr: $0[kSecAttrKeyType] as! NSNumber)
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let keySize = $0[kSecAttrKeySizeInBits] as! Int
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let publicKeyRef = $0[kSecValueRef] as! SecKey
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let publicKeySecRef = SecKeyCopyPublicKey(publicKeyRef)!
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let publicKeyAttributes = SecKeyCopyAttributes(publicKeySecRef) as! [CFString: Any]
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let publicKey = publicKeyAttributes[kSecValueData] as! Data
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return SmartCard.Secret(id: tokenID, name: name, algorithm: algorithm, keySize: keySize, publicKey: publicKey)
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}
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secrets.append(contentsOf: wrapped)
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}
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}
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// MARK: Smart Card specific encryption/decryption/verification
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extension SmartCard.Store {
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/// Encrypts a payload with a specified key.
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/// - Parameters:
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/// - data: The payload to encrypt.
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/// - secret: The secret to encrypt with.
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/// - Returns: The encrypted data.
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/// - Warning: Encryption functions are deliberately only exposed on a library level, and are not exposed in Secretive itself to prevent users from data loss. Any pull requests which expose this functionality in the app will not be merged.
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public func encrypt(data: Data, with secret: SecretType) throws -> Data {
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let context = LAContext()
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context.localizedReason = "encrypt data using secret \"\(secret.name)\""
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context.localizedCancelTitle = "Deny"
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let attributes = KeychainDictionary([
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kSecAttrKeyType: secret.algorithm.secAttrKeyType,
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kSecAttrKeySizeInBits: secret.keySize,
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kSecAttrKeyClass: kSecAttrKeyClassPublic,
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kSecUseAuthenticationContext: context
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])
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var encryptError: SecurityError?
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let untyped: CFTypeRef? = SecKeyCreateWithData(secret.publicKey as CFData, attributes, &encryptError)
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guard let untypedSafe = untyped else {
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throw KeychainError(statusCode: errSecSuccess)
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}
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let key = untypedSafe as! SecKey
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guard let signature = SecKeyCreateEncryptedData(key, encryptionAlgorithm(for: secret), data as CFData, &encryptError) else {
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throw SigningError(error: encryptError)
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}
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return signature as Data
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}
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/// Decrypts a payload with a specified key.
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/// - Parameters:
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/// - data: The payload to decrypt.
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/// - secret: The secret to decrypt with.
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/// - Returns: The decrypted data.
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/// - Warning: Encryption functions are deliberately only exposed on a library level, and are not exposed in Secretive itself to prevent users from data loss. Any pull requests which expose this functionality in the app will not be merged.
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public func decrypt(data: Data, with secret: SecretType) throws -> Data {
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guard let tokenID = tokenID else { fatalError() }
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let context = LAContext()
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context.localizedReason = "decrypt data using secret \"\(secret.name)\""
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context.localizedCancelTitle = "Deny"
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let attributes = KeychainDictionary([
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kSecClass: kSecClassKey,
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kSecAttrKeyClass: kSecAttrKeyClassPrivate,
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kSecAttrApplicationLabel: secret.id as CFData,
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kSecAttrTokenID: tokenID,
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kSecUseAuthenticationContext: context,
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kSecReturnRef: true
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])
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var untyped: CFTypeRef?
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let status = SecItemCopyMatching(attributes, &untyped)
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if status != errSecSuccess {
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throw KeychainError(statusCode: status)
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}
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guard let untypedSafe = untyped else {
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throw KeychainError(statusCode: errSecSuccess)
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}
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let key = untypedSafe as! SecKey
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var encryptError: SecurityError?
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guard let signature = SecKeyCreateDecryptedData(key, encryptionAlgorithm(for: secret), data as CFData, &encryptError) else {
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throw SigningError(error: encryptError)
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}
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return signature as Data
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}
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private func encryptionAlgorithm(for secret: SecretType) -> SecKeyAlgorithm {
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switch (secret.algorithm, secret.keySize) {
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case (.ellipticCurve, 256):
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return .eciesEncryptionCofactorVariableIVX963SHA256AESGCM
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case (.ellipticCurve, 384):
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return .eciesEncryptionCofactorVariableIVX963SHA256AESGCM
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case (.rsa, 1024), (.rsa, 2048):
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return .rsaEncryptionOAEPSHA512AESGCM
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default:
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fatalError()
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}
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}
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}
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extension TKTokenWatcher {
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/// All available tokens, excluding the Secure Enclave.
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fileprivate var nonSecureEnclaveTokens: [String] {
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tokenIDs.filter { !$0.contains("setoken") }
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}
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}
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