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Insecure encryption algorithm - Blowfish

Need​

Implementation of secure encryption algorithms

Context​

  • Usage of Ruby for building web applications and scripting
  • Usage of blowfish for encryption and decryption operations

Description​

Non compliant code​

require 'blowfish'

key = "secret_key"
blowfish = Crypt::Blowfish.new(key)
plain_text = "Sensitive Information"
cipher_text = blowfish.encrypt_block(plain_text)

The above code is a simple encryption routine implemented in Ruby using the Blowfish algorithm. The Blowfish algorithm is an insecure encryption algorithm and is not recommended for use in new systems.

In the code:

  • We first import the blowfish library.
  • We then define a secret key as secret_key. This key is used to encrypt and decrypt the data.
  • We initialize a new instance of Crypt::Blowfish with our secret key.
  • We define a plain_text variable that contains the sensitive information we want to encrypt.
  • Finally, we call encrypt_block method on the blowfish instance to encrypt our plain text. The result is stored in cipher_text.

The vulnerability here is that the Blowfish algorithm is considered insecure, primarily because it uses a small block size of 64 bits. This small block size makes it vulnerable to birthday attacks, which can reveal patterns in the encrypted data. Moreover, Blowfish also has issues with weak keys, which can significantly reduce the security of the encrypted data.

To secure this code, it is recommended to use a more secure encryption algorithm, such as AES (Advanced Encryption Standard), which has a larger block size and is currently the standard for data encryption.

Steps​

  • Replace the insecure encryption algorithm (Blowfish) with a more secure algorithm.
  • Research and choose a strong encryption algorithm that is recommended for your application's security requirements.
  • Update the code to use the chosen secure encryption algorithm.
  • Ensure that the encryption algorithm supports a secure key length and key management.
  • Generate a strong and random encryption key.
  • Store the encryption key securely, such as in a secure key management system or environment variable.
  • Update the code to use the secure encryption key for encryption and decryption operations.
  • Test the updated code thoroughly to ensure the encryption and decryption operations work correctly.
  • Monitor for any potential vulnerabilities or weaknesses in the chosen encryption algorithm and stay updated with security best practices.
  • Regularly review and update the encryption implementation as needed to maintain a strong security posture.

Compliant code​

require 'openssl'
require 'base64'

key = OpenSSL::Cipher.new('aes-256-cbc').random_key
cipher = OpenSSL::Cipher.new('aes-256-cbc')
cipher.encrypt
cipher.key = key
plain_text = "Sensitive Information"
encrypted = cipher.update(plain_text) + cipher.final
cipher_text = Base64.encode64(encrypted)

The above code replaces the insecure Blowfish encryption algorithm with the more secure AES-256-CBC encryption algorithm.

Here's a breakdown of what the code does:

  1. OpenSSL::Cipher.new('aes-256-cbc').random_key generates a random key for AES-256-CBC encryption.
  2. cipher = OpenSSL::Cipher.new('aes-256-cbc') creates a new cipher for AES-256-CBC.
  3. cipher.encrypt sets the cipher to encryption mode.
  4. cipher.key = key sets the cipher's key to the previously generated key.
  5. encrypted = cipher.update(plain_text) + cipher.final encrypts the plain text.
  6. cipher_text = Base64.encode64(encrypted) encodes the encrypted text in Base64 so it can be safely transmitted or stored.

This code ensures that the sensitive information is encrypted using a secure encryption algorithm and key. The key is randomly generated and should be securely stored and managed. The encrypted information is then Base64 encoded for safe transmission or storage.

Remember to test the code thoroughly to ensure the encryption and decryption operations work correctly. Also, monitor for any potential vulnerabilities or weaknesses in the chosen encryption algorithm and stay updated with security best practices. Regularly review and update the encryption implementation as needed to maintain a strong security posture.

References​

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