Save and Load from KeyChain | Swift
How to simply store a String in Keychain and load when needed. There are several SO solution which mostly refers to Git repo. But I need the smallest and the simplest solution on latest Swift. Certainly, I don't want to add git framework for simply storing a password in my project.
There are similar solution Save and retrieve value via KeyChain , which did not work for me. Tired with compiler errors.
Answer
##Simplest Source##
import Foundation
import Security
// Constant Identifiers
let userAccount = "AuthenticatedUser"
let accessGroup = "SecuritySerivice"
/**
* User defined keys for new entry
* Note: add new keys for new secure item and use them in load and save methods
*/
let passwordKey = "KeyForPassword"
// Arguments for the keychain queries
let kSecClassValue = NSString(format: kSecClass)
let kSecAttrAccountValue = NSString(format: kSecAttrAccount)
let kSecValueDataValue = NSString(format: kSecValueData)
let kSecClassGenericPasswordValue = NSString(format: kSecClassGenericPassword)
let kSecAttrServiceValue = NSString(format: kSecAttrService)
let kSecMatchLimitValue = NSString(format: kSecMatchLimit)
let kSecReturnDataValue = NSString(format: kSecReturnData)
let kSecMatchLimitOneValue = NSString(format: kSecMatchLimitOne)
public class KeychainService: NSObject {
/**
* Exposed methods to perform save and load queries.
*/
public class func savePassword(token: NSString) {
self.save(passwordKey, data: token)
}
public class func loadPassword() -> NSString? {
return self.load(passwordKey)
}
/**
* Internal methods for querying the keychain.
*/
private class func save(service: NSString, data: NSString) {
let dataFromString: NSData = data.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!
// Instantiate a new default keychain query
let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, userAccount, dataFromString], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecValueDataValue])
// Delete any existing items
SecItemDelete(keychainQuery as CFDictionaryRef)
// Add the new keychain item
SecItemAdd(keychainQuery as CFDictionaryRef, nil)
}
private class func load(service: NSString) -> NSString? {
// Instantiate a new default keychain query
// Tell the query to return a result
// Limit our results to one item
let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, userAccount, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])
var dataTypeRef :AnyObject?
// Search for the keychain items
let status: OSStatus = SecItemCopyMatching(keychainQuery, &dataTypeRef)
var contentsOfKeychain: NSString? = nil
if status == errSecSuccess {
if let retrievedData = dataTypeRef as? NSData {
contentsOfKeychain = NSString(data: retrievedData, encoding: NSUTF8StringEncoding)
}
} else {
print("Nothing was retrieved from the keychain. Status code \(status)")
}
return contentsOfKeychain
}
}
##Example of Calling##
KeychainService.savePassword("Pa55worD")
let password = KeychainService.loadPassword() // password = "Pa55worD"
##SWIFT 4: VERSION WITH UPDATE AND REMOVE PASSWORD
import Cocoa
import Security
// see https://stackoverflow.com/a/37539998/1694526
// Arguments for the keychain queries
let kSecClassValue = NSString(format: kSecClass)
let kSecAttrAccountValue = NSString(format: kSecAttrAccount)
let kSecValueDataValue = NSString(format: kSecValueData)
let kSecClassGenericPasswordValue = NSString(format: kSecClassGenericPassword)
let kSecAttrServiceValue = NSString(format: kSecAttrService)
let kSecMatchLimitValue = NSString(format: kSecMatchLimit)
let kSecReturnDataValue = NSString(format: kSecReturnData)
let kSecMatchLimitOneValue = NSString(format: kSecMatchLimitOne)
public class KeychainService: NSObject {
class func updatePassword(service: String, account:String, data: String) {
if let dataFromString: Data = data.data(using: String.Encoding.utf8, allowLossyConversion: false) {
// Instantiate a new default keychain query
let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue])
let status = SecItemUpdate(keychainQuery as CFDictionary, [kSecValueDataValue:dataFromString] as CFDictionary)
if (status != errSecSuccess) {
if let err = SecCopyErrorMessageString(status, nil) {
print("Read failed: \(err)")
}
}
}
}
class func removePassword(service: String, account:String) {
// Instantiate a new default keychain query
let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account, kCFBooleanTrue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue])
// Delete any existing items
let status = SecItemDelete(keychainQuery as CFDictionary)
if (status != errSecSuccess) {
if let err = SecCopyErrorMessageString(status, nil) {
print("Remove failed: \(err)")
}
}
}
class func savePassword(service: String, account:String, data: String) {
if let dataFromString = data.data(using: String.Encoding.utf8, allowLossyConversion: false) {
// Instantiate a new default keychain query
let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account, dataFromString], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecValueDataValue])
// Add the new keychain item
let status = SecItemAdd(keychainQuery as CFDictionary, nil)
if (status != errSecSuccess) { // Always check the status
if let err = SecCopyErrorMessageString(status, nil) {
print("Write failed: \(err)")
}
}
}
}
class func loadPassword(service: String, account:String) -> String? {
// Instantiate a new default keychain query
// Tell the query to return a result
// Limit our results to one item
let keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, account, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])
var dataTypeRef :AnyObject?
// Search for the keychain items
let status: OSStatus = SecItemCopyMatching(keychainQuery, &dataTypeRef)
var contentsOfKeychain: String?
if status == errSecSuccess {
if let retrievedData = dataTypeRef as? Data {
contentsOfKeychain = String(data: retrievedData, encoding: String.Encoding.utf8)
}
} else {
print("Nothing was retrieved from the keychain. Status code \(status)")
}
return contentsOfKeychain
}
}
You need to imagine the following wired up to a text input field and a label, then having four buttons wired up, one for each of the methods.
class ViewController: NSViewController {
@IBOutlet weak var enterPassword: NSTextField!
@IBOutlet weak var retrievedPassword: NSTextField!
let service = "myService"
let account = "myAccount"
// will only work after
@IBAction func updatePassword(_ sender: Any) {
KeychainService.updatePassword(service: service, account: account, data: enterPassword.stringValue)
}
@IBAction func removePassword(_ sender: Any) {
KeychainService.removePassword(service: service, account: account)
}
@IBAction func passwordSet(_ sender: Any) {
let password = enterPassword.stringValue
KeychainService.savePassword(service: service, account: account, data: password)
}
@IBAction func passwordGet(_ sender: Any) {
if let str = KeychainService.loadPassword(service: service, account: account) {
retrievedPassword.stringValue = str
}
else {retrievedPassword.stringValue = "Password does not exist" }
}
}
##Swift 5## Kosuke's version for swift 5
import Security
import UIKit
class KeyChain {
class func save(key: String, data: Data) -> OSStatus {
let query = [
kSecClass as String : kSecClassGenericPassword as String,
kSecAttrAccount as String : key,
kSecValueData as String : data ] as [String : Any]
SecItemDelete(query as CFDictionary)
return SecItemAdd(query as CFDictionary, nil)
}
class func load(key: String) -> Data? {
let query = [
kSecClass as String : kSecClassGenericPassword,
kSecAttrAccount as String : key,
kSecReturnData as String : kCFBooleanTrue!,
kSecMatchLimit as String : kSecMatchLimitOne ] as [String : Any]
var dataTypeRef: AnyObject? = nil
let status: OSStatus = SecItemCopyMatching(query as CFDictionary, &dataTypeRef)
if status == noErr {
return dataTypeRef as! Data?
} else {
return nil
}
}
class func createUniqueID() -> String {
let uuid: CFUUID = CFUUIDCreate(nil)
let cfStr: CFString = CFUUIDCreateString(nil, uuid)
let swiftString: String = cfStr as String
return swiftString
}
}
extension Data {
init<T>(from value: T) {
var value = value
self.init(buffer: UnsafeBufferPointer(start: &value, count: 1))
}
func to<T>(type: T.Type) -> T {
return self.withUnsafeBytes { $0.load(as: T.self) }
}
}
Example usage:
let int: Int = 555
let data = Data(from: int)
let status = KeyChain.save(key: "MyNumber", data: data)
print("status: ", status)
if let receivedData = KeyChain.load(key: "MyNumber") {
let result = receivedData.to(type: Int.self)
print("result: ", result)
}