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Insecure encryption algorithm - Insecure Elliptic Curve

Need​

Secure encryption algorithm for data protection

Context​

  • Usage of TypeScript for static typing and enhanced tooling in Node.js development
  • Usage of Express for building web applications and APIs
  • Usage of crypto for cryptographic operations and secure data handling

Description​

Non compliant code​

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

const app = express();

app.get('/encrypt', (req, res) => {
  const data = req.query.data;
  
  // Insecure elliptic curve parameters
  const curve = crypto.createECDH('secp192k1');
  const publicKey = curve.generateKeys();
  
  const encryptedData = crypto.publicEncrypt(publicKey, Buffer.from(data));
  
  res.send(encryptedData.toString('base64'));
});

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

The vulnerability in this code lies in the use of an insecure elliptic curve for encryption. Specifically, the code uses the 'secp192k1' curve, which is known to be weak and vulnerable to attacks.

The 'crypto' module is used to create an instance of an elliptic curve Diffie-Hellman (ECDH) object with the 'secp192k1' curve. This curve is considered insecure because it has a small key size and is susceptible to various cryptographic attacks.

The code then generates a public key using the insecure curve and uses it to encrypt the data received from the client. The encrypted data is then sent back to the client.

The impact of using an insecure elliptic curve includes producing incorrect results for some unusual curve points, exposing secret data when the input is not a curve point, exposing secret data through branch synchronization, and exposing secret data through cache synchronization.

To address this vulnerability, it is recommended to ensure that the curves used for ECDH are safe for both the Elliptic Curve Discrete Logarithm Problem (ECDLP) and elliptic curve cryptography (ECC) in general. This involves using curves with larger key sizes and that have been thoroughly vetted and proven to be secure.

Steps​

  • Replace the insecure elliptic curve 'secp192k1' with a secure elliptic curve.
  • Ensure that the secure elliptic curve is safe for both ECDLP and ECC in general.
  • Update the code to use the secure elliptic curve parameters.
  • Test the updated code to ensure it is functioning correctly.

Compliant code​

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

const app = express();

app.get('/encrypt', (req, res) => {
  const data = req.query.data;
  
  // Secure elliptic curve parameters
  const curve = crypto.createECDH('secp256k1');
  const publicKey = curve.generateKeys();
  
  const encryptedData = crypto.publicEncrypt(publicKey, Buffer.from(data));
  
  res.send(encryptedData.toString('base64'));
});

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

The fixed code addresses the vulnerability by ensuring the use of a secure elliptic curve and implementing proper encryption practices. Here's an explanation of the changes made:

  1. The code imports the necessary modules, express and crypto, to set up the server and perform cryptographic operations.

  2. The app variable is created using the express module, which initializes the Express application.

  3. The /encrypt route is defined using the app.get method. This route is responsible for encrypting the data received as a query parameter.

  4. Inside the route handler, the data query parameter is extracted from the request.

  5. The crypto.createECDH method is used to create an instance of the elliptic curve Diffie-Hellman (ECDH) algorithm with the 'secp256k1' curve, which is a widely accepted and secure curve.

  6. The generateKeys method is called on the curve object to generate a new pair of public and private keys.

  7. The crypto.publicEncrypt method is used to encrypt the data using the generated publicKey. The encrypted data is stored in the encryptedData variable.

  8. The encrypted data is converted to a base64 string using the toString method with the 'base64' encoding.

  9. The encrypted data is sent as the response using the res.send method.

  10. The server is started on port 3000 using the app.listen method, and a message is logged to the console.

By using a secure elliptic curve and following best practices for encryption, the fixed code ensures that the system is not vulnerable to the insecure elliptic curve vulnerability.

References​

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