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Insecure encryption algorithm - Perfect Forward Secrecy

Need​

Implementation of secure encryption algorithms with Perfect Forward Secrecy

Context​

  • Usage of Scala for functional and object-oriented programming in the JVM environment
  • Usage of javax.crypto.Cipher for encryption and decryption operations
  • Usage of javax.crypto.spec.SecretKeySpec for generating secret keys in cryptography

Description​

Non compliant code​

import javax.crypto.Cipher
import javax.crypto.spec.SecretKeySpec

val secret: String = "ThisIsASecretKey"
val skeySpec: SecretKeySpec = new SecretKeySpec(secret.getBytes, "Blowfish")
val cipher: Cipher = Cipher.getInstance("Blowfish")
cipher.init(Cipher.ENCRYPT_MODE, skeySpec)

val message: String = "This is a sensitive message"
val encrypted: Array[Byte] = cipher.doFinal(message.getBytes)

The above Scala code is using the Blowfish encryption algorithm, which does not support Perfect Forward Secrecy (PFS). PFS is a property of secure communication protocols in which compromise of long-term keys does not compromise past session keys.

In this code, the secret variable is the private key used for encryption and decryption. The skeySpec is the secret key specification for the cipher instance. The cipher instance is initialized with the encryption mode and the secret key specification.

The message that needs to be encrypted is stored in the message variable. The doFinal method of the cipher instance is used to encrypt the message.

The problem here is that if the secret (private key) is compromised, all past and future messages encrypted with this key can be decrypted. This is because Blowfish doesn't support perfect forward secrecy.

In a system with perfect forward secrecy, if a key is compromised, only the data encrypted with that key is at risk. Past messages encrypted with different keys are safe. This code does not provide this level of security, making it vulnerable to attacks where the private key is compromised.

Steps​

  • Replace the insecure encryption algorithm with a secure one.
  • Use a strong and secure encryption algorithm that provides Perfect Forward Secrecy (PFS).
  • Ensure that the encryption algorithm used is recommended by security experts and has no known vulnerabilities.
  • Generate a strong and random encryption key.
  • Store the encryption key securely and protect it from unauthorized access.
  • Implement a key rotation mechanism to periodically change the encryption key.
  • Use a secure key management system to handle the encryption keys.
  • Encrypt the sensitive message using the secure encryption algorithm and the generated encryption key.
  • Ensure that the encryption process follows best practices and industry standards.
  • Regularly update the encryption algorithm and libraries used in the application to stay protected against new vulnerabilities.

Compliant code​

import java.security.{KeyPairGenerator, SecureRandom}
import javax.crypto.Cipher
import javax.crypto.spec.SecretKeySpec
import org.bouncycastle.jce.provider.BouncyCastleProvider

// Generate a strong and random encryption key
val keyGen = KeyPairGenerator.getInstance("RSA", new BouncyCastleProvider())
keyGen.initialize(2048, new SecureRandom())
val keyPair = keyGen.generateKeyPair()

// Use a secure encryption algorithm that provides Perfect Forward Secrecy (PFS)
val cipher: Cipher = Cipher.getInstance("RSA/None/OAEPWithSHA1AndMGF1Padding", new BouncyCastleProvider())
cipher.init(Cipher.ENCRYPT_MODE, keyPair.getPublic)

val message: String = "This is a sensitive message"
val encrypted: Array[Byte] = cipher.doFinal(message.getBytes)

The above code fixes the vulnerability by replacing the insecure Blowfish encryption algorithm with a secure RSA encryption algorithm that provides Perfect Forward Secrecy (PFS).

The RSA encryption algorithm is recommended by security experts and has no known vulnerabilities. It uses a pair of keys: a public key for encryption and a private key for decryption. The public key is used to encrypt the sensitive message, and the private key is used to decrypt the encrypted message.

The code generates a strong and random encryption key using the KeyPairGenerator class. The KeyPairGenerator class is initialized with the RSA encryption algorithm, a key size of 2048 bits, and a secure random number generator. The key size of 2048 bits is recommended for RSA encryption as it provides a high level of security.

The Cipher class is used to encrypt the sensitive message using the RSA encryption algorithm and the generated public key. The Cipher class is initialized with the RSA encryption algorithm and the public key. The sensitive message is encrypted using the doFinal method of the Cipher class.

The Bouncy Castle provider is used as it provides a wide range of cryptographic algorithms and has a strong reputation for security.

The encryption key is stored securely in the KeyPair object and is protected from unauthorized access. A key rotation mechanism and a secure key management system should be implemented to handle the encryption keys.

The encryption process follows best practices and industry standards. The encryption algorithm and libraries used in the application should be regularly updated to stay protected against new vulnerabilities.

References​

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