Save and Load from KeyChain | Swift [duplicate]

Question

This question already has an answer here:

• Save and retrieve value via KeyChain 5 answers

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 1

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" }
    }
}