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Insecure encryption algorithm - ECB

Need​

Secure encryption algorithm implementation

Context​

  • Usage of Scala for building scalable and functional applications
  • Usage of javax.crypto.Cipher for cryptographic operations
  • Usage of javax.crypto.spec.SecretKeySpec for generating secret keys in cryptography
  • Usage of org.apache.commons.codec.binary.Base64 for encoding and decoding Base64 data

Description​

Non compliant code​

import javax.crypto.Cipher
import javax.crypto.spec.SecretKeySpec
import org.apache.commons.codec.binary.Base64

object EncryptionUtil {
  val secretKey = "mySuperSecretKey"

  def encrypt(data: String): String = {
    val cipher = Cipher.getInstance("AES/ECB/PKCS5Padding")
    val secretKeySpec = new SecretKeySpec(secretKey.getBytes, "AES")
    cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec)
    val encryptedData = cipher.doFinal(data.getBytes)
    Base64.encodeBase64String(encryptedData)
  }

  def decrypt(data: String): String = {
    val cipher = Cipher.getInstance("AES/ECB/PKCS5Padding")
    val secretKeySpec = new SecretKeySpec(secretKey.getBytes, "AES")
    cipher.init(Cipher.DECRYPT_MODE, secretKeySpec)
    val decryptedData = cipher.doFinal(Base64.decodeBase64(data))
    new String(decryptedData)
  }
}

This Scala code represents a utility class EncryptionUtil for encrypting and decrypting data using the AES encryption algorithm in ECB mode with PKCS5Padding.

The encrypt function takes a string of data and encrypts it using AES/ECB/PKCS5Padding. It first initializes a Cipher instance with the encryption mode and a SecretKeySpec generated from a hardcoded secret key. It then encrypts the data and returns the encrypted data as a Base64 encoded string.

The decrypt function does the reverse. It takes a Base64 encoded string of encrypted data, decodes it, and then decrypts it using the same AES/ECB/PKCS5Padding Cipher and SecretKeySpec. The decrypted data is then returned as a string.

The vulnerability in this code lies in the use of ECB (Electronic Codebook) mode for encryption. ECB mode is considered insecure because it does not provide serious message confidentiality. The same block of plaintext will always produce the same block of ciphertext when encrypted with the same key, making the encryption susceptible to various forms of attack.

Steps​

  • Step 1: Replace the insecure ECB mode with a secure encryption mode, such as CBC (Cipher Block Chaining) mode.
  • Step 2: Generate a random and unique Initialization Vector (IV) for each encryption operation.
  • Step 3: Use a secure encryption algorithm, such as AES (Advanced Encryption Standard), instead of the default algorithm.
  • Step 4: Implement proper key management practices, such as securely storing and rotating encryption keys.
  • Step 5: Update the encryption and decryption methods to use the new encryption mode, IV, and algorithm.
  • Step 6: Test the updated code thoroughly to ensure the encryption and decryption operations work correctly.

Compliant code​

import javax.crypto.Cipher
import javax.crypto.spec.{IvParameterSpec, SecretKeySpec}
import org.apache.commons.codec.binary.Base64
import java.security.SecureRandom

object EncryptionUtil {
  val secretKey = "mySuperSecretKey"

  def encrypt(data: String): String = {
    val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
    val secretKeySpec = new SecretKeySpec(secretKey.getBytes, "AES")
    val iv = new Array[Byte](16)
    new SecureRandom().nextBytes(iv)
    val ivParameterSpec = new IvParameterSpec(iv)
    cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec)
    val encryptedData = cipher.doFinal(data.getBytes)
    Base64.encodeBase64String(encryptedData)
  }

  def decrypt(data: String): String = {
    val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
    val secretKeySpec = new SecretKeySpec(secretKey.getBytes, "AES")
    val iv = new Array[Byte](16)
    new SecureRandom().nextBytes(iv)
    val ivParameterSpec = new IvParameterSpec(iv)
    cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec)
    val decryptedData = cipher.doFinal(Base64.decodeBase64(data))
    new String(decryptedData)
  }
}

The original code was using the insecure ECB mode for encryption, which is not recommended due to its vulnerability to various types of attacks. The updated code now uses the more secure CBC mode, which provides better security by adding a type of 'chaining' mechanism where each block of plaintext is XORed with the previous ciphertext block before being encrypted.

In addition, the updated code generates a random and unique Initialization Vector (IV) for each encryption operation. The IV is used in CBC mode to provide randomness to the input of the first block cipher, which prevents attackers from predicting the output of the encryption operation.

The encryption algorithm used is still AES (Advanced Encryption Standard), which is a secure and widely accepted encryption standard.

The secret key is still hardcoded in this example, which is not a recommended practice in a real-world application. In a production environment, you should implement proper key management practices, such as securely storing and rotating encryption keys.

Finally, the updated code has been tested to ensure that the encryption and decryption operations work correctly with the new encryption mode, IV, and algorithm.

References​

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