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Insecure encryption algorithm

Need​

Implementation of secure encryption algorithms

Context​

  • Usage of Swift for iOS and macOS app development
  • Usage of UIKit for building modern and responsive user interfaces
  • Usage of CryptoSwift for cryptographic operations in Swift development

Description​

Non compliant code​

import UIKit
import CryptoSwift

class ViewController: UIViewController {

    @IBOutlet weak var textField: UITextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    @IBAction func encryptButtonTapped(_ sender: UIButton) {
        let data = textField.text?.data(using: .utf8)
        let encryptedData = try! DES.encrypt(data!, key: "12345678")
        print("Encrypted Data: \\(encryptedData)")
    }
}

The above Swift code is an example of an insecure encryption algorithm vulnerability. This code is part of a view controller in an iOS application that handles text encryption when a button is clicked.

The encryptButtonTapped function is triggered when the encryption button is tapped. It takes the text from a text field, converts it into data using UTF-8 encoding, and then encrypts the data using the DES encryption algorithm.

The DES encryption algorithm is used here, which is considered insecure for many applications. This is because it uses a small key size (56-bits), which makes it vulnerable to brute-force attacks. Modern computing power can easily break DES encryption, making it unsuitable for protecting sensitive data.

The key used for encryption is also hardcoded into the application ("12345678"), which is another security vulnerability. If an attacker can access the application's code (which is often possible), they can easily find this key and use it to decrypt any data encrypted with this algorithm.

In summary, the use of DES encryption and a hardcoded key makes this code insecure and vulnerable to attacks.

Steps​

  • Replace the insecure encryption algorithm with a secure one.
  • Use a strong encryption algorithm such as AES instead of DES.
  • Ensure that the encryption algorithm is implemented correctly and securely.
  • Generate a strong encryption key using a secure random number generator.
  • Store the encryption key securely and protect it from unauthorized access.
  • Consider using additional security measures such as encryption at rest and in transit.

Compliant code​

import UIKit
import CryptoSwift

class ViewController: UIViewController {

    @IBOutlet weak var textField: UITextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    @IBAction func encryptButtonTapped(_ sender: UIButton) {
        guard let data = textField.text?.data(using: .utf8) else { return }
        let key = generateRandomKey()
        let iv = generateRandomIV()
        let encryptedData = try! AES(key: key, iv: iv).encrypt([UInt8](data))
        print("Encrypted Data: \\(encryptedData)")
    }
    
    func generateRandomKey() -> String {
        let keyData = Data.randomBytes(length: 32)
        return keyData.toHexString()
    }
    
    func generateRandomIV() -> String {
        let ivData = Data.randomBytes(length: 16)
        return ivData.toHexString()
    }
}

The previous code was using the DES encryption algorithm, which is considered insecure due to its small key size and susceptibility to brute-force attacks. The new code replaces DES with AES, a much more secure encryption algorithm.

The encryptButtonTapped function now uses AES for encryption. It first checks if the text field's text can be converted to data. If not, it returns immediately. It then generates a random key and initialization vector (IV) for the AES encryption. The key is 32 bytes long and the IV is 16 bytes long, which are the recommended lengths for AES.

The generateRandomKey and generateRandomIV functions generate random data of the specified length. The random data is then converted to a hexadecimal string, which is used as the key or IV.

The key and IV are generated each time the button is tapped, ensuring that each encryption operation uses a different key and IV. This increases the security of the encryption.

Please note that the key and IV should be stored securely if they need to be used for decryption later. The current code does not include secure key and IV storage.

References​

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