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Insecure encryption algorithm - Blowfish

Need​

Secure encryption algorithm for protecting sensitive information

Context​

  • Usage of TypeScript for statically typed JavaScript development
  • Usage of Express for building web applications and APIs
  • Usage of crypto for cryptographic operations

Description​

Non compliant code​

import express from 'express';
import crypto from 'crypto';

const app = express();

app.get('/encrypt', (req, res) => {
  const secretKey = 'mySecretKey';
  const data = 'mySensitiveData';

  const cipher = crypto.createCipher('blowfish', secretKey);
  let encryptedData = cipher.update(data, 'utf8', 'hex');
  encryptedData += cipher.final('hex');

  res.send(encryptedData);
});

app.get('/decrypt', (req, res) => {
  const secretKey = 'mySecretKey';
  const encryptedData = req.query.data as string;

  const decipher = crypto.createDecipher('blowfish', secretKey);
  let decryptedData = decipher.update(encryptedData, 'hex', 'utf8');
  decryptedData += decipher.final('utf8');

  res.send(decryptedData);
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

The vulnerability in this code lies in the use of the insecure encryption algorithm, Blowfish.

In the /encrypt route, the code uses the crypto.createCipher function to create a cipher object with the Blowfish algorithm and a secret key. It then encrypts the sensitive data using this cipher object. The encrypted data is sent as the response.

In the /decrypt route, the code uses the crypto.createDecipher function to create a decipher object with the Blowfish algorithm and the same secret key. It then attempts to decrypt the data received as a query parameter using this decipher object. The decrypted data is sent as the response.

The vulnerability arises from the use of the Blowfish algorithm, which is considered insecure. It has known vulnerabilities and weaknesses that can be exploited to decrypt the encrypted data. Attackers with sufficient knowledge and resources can potentially decrypt the credentials stored in the code.

The recommendation to mitigate this vulnerability is to use secure encryption algorithms such as AES or RSA. These algorithms have undergone extensive analysis and are widely accepted as secure. By replacing the Blowfish algorithm with a secure algorithm, the code can ensure the confidentiality and integrity of the encrypted data.

Steps​

  • Replace the use of the insecure Blowfish encryption algorithm with a secure algorithm such as AES or RSA.
  • Update the code to use the secure algorithm for encryption and decryption.
  • Generate a secure secret key for encryption and decryption.
  • Update the code to use the secure secret key for encryption and decryption.
  • Test the updated code to ensure it functions correctly.

Compliant code​

import express from 'express';
import crypto from 'crypto';

const app = express();

app.get('/encrypt', (req, res) => {
  const secretKey = crypto.randomBytes(32); // Generate a secure secret key
  const data = 'mySensitiveData';

  const cipher = crypto.createCipher('aes-256-cbc', secretKey);
  let encryptedData = cipher.update(data, 'utf8', 'hex');
  encryptedData += cipher.final('hex');

  res.send({
    encryptedData,
    secretKey: secretKey.toString('hex')
  });
});

app.get('/decrypt', (req, res) => {
  const secretKey = Buffer.from(req.query.secretKey as string, 'hex');
  const encryptedData = req.query.data as string;

  const decipher = crypto.createDecipher('aes-256-cbc', secretKey);
  let decryptedData = decipher.update(encryptedData, 'hex', 'utf8');
  decryptedData += decipher.final('utf8');

  res.send(decryptedData);
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

The fixed code addresses the vulnerability by using a secure encryption algorithm (AES-256-CBC) instead of the insecure Blowfish algorithm. Here's an explanation of the changes made:

  1. Importing the necessary modules: The code imports the 'express' and 'crypto' modules to handle the server and encryption operations, respectively.

  2. Generating a secure secret key: The code uses the crypto.randomBytes() function to generate a secure secret key of 32 bytes. This ensures that the key is randomly generated and difficult to guess.

  3. Encrypting the data: The code creates a cipher object using crypto.createCipher() with the secure secret key and the AES-256-CBC algorithm. It then encrypts the sensitive data using the cipher.update() and cipher.final() methods, and stores the encrypted data in the encryptedData variable.

  4. Sending the encrypted data and secret key: The code sends the encrypted data and the secret key (converted to a hexadecimal string) as a response to the '/encrypt' endpoint.

  5. Decrypting the data: The code receives the secret key and encrypted data as query parameters from the '/decrypt' endpoint. It converts the secret key from a hexadecimal string to a buffer using Buffer.from(). Then, it creates a decipher object using crypto.createDecipher() with the secret key and the AES-256-CBC algorithm. The code decrypts the encrypted data using the decipher.update() and decipher.final() methods, and stores the decrypted data in the decryptedData variable.

  6. Sending the decrypted data: The code sends the decrypted data as a response to the '/decrypt' endpoint.

  7. Starting the server: The code starts the server on port 3000 and logs a message to indicate that the server is running.

By using the secure AES-256-CBC algorithm and generating a secure secret key, the code ensures that the encrypted data is protected and can only be decrypted with the correct key.

References​

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