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Insecure encryption algorithm - DSA

Need​

Implementation of secure encryption algorithms

Context​

  • Usage of Java 8 for developing applications with enhanced features and performance
  • Usage of java.security for implementing security features in Java applications
  • Usage of javax.crypto for cryptographic operations in Java

Description​

Non compliant code​

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import javax.crypto.Cipher;

public class InsecureEncryption {
    public static void main(String[] args) throws Exception {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
        keyGen.initialize(1024, random);
        KeyPair pair = keyGen.generateKeyPair();
        Cipher cipher = Cipher.getInstance("DSA");
        cipher.init(Cipher.ENCRYPT_MODE, pair.getPublic());
        byte[] cipherText = cipher.doFinal("This is an insecure encryption".getBytes());
        System.out.println(new String(cipherText));
    }
}

In the above code, the InsecureEncryption class is using the Digital Signature Algorithm (DSA) for encryption which is not secure.

In the main method, a KeyPairGenerator instance is created with the "DSA" algorithm. A SecureRandom instance is also created with the "SHA1PRNG" algorithm. The key generator is initialized with a key size of 1024 and the secure random instance.

A key pair is generated using the generateKeyPair method. A Cipher instance is created with the "DSA" algorithm. The cipher is initialized in encryption mode with the public key from the key pair.

A string is encrypted using the doFinal method of the cipher and printed to the console.

The vulnerability here is the use of the DSA algorithm for encryption. DSA is not meant to be used for encryption or secrecy of data. It is a digital signature algorithm designed to provide authenticity and integrity, not confidentiality. Using it for encryption is a misuse of the algorithm and can lead to security vulnerabilities.

Steps​

  • Replace the insecure encryption algorithm (DSA) with a secure encryption algorithm.
  • Use a strong and secure key generation algorithm.
  • Ensure the use of a secure random number generator.
  • Use a secure cipher algorithm for encryption.
  • Ensure proper initialization and configuration of the cipher.
  • Encrypt sensitive data using the updated secure encryption algorithm.

Compliant code​

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import javax.crypto.Cipher;

public class SecureEncryption {
    public static void main(String[] args) throws Exception {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
        SecureRandom random = SecureRandom.getInstanceStrong();
        keyGen.initialize(2048, random);
        KeyPair pair = keyGen.generateKeyPair();
        Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, pair.getPublic());
        byte[] cipherText = cipher.doFinal("This is a secure encryption".getBytes());
        System.out.println(new String(cipherText, "UTF8"));
    }
}

The above code is a fixed version of the previously insecure encryption code. The changes made are as follows:

  1. The insecure DSA encryption algorithm has been replaced with the secure RSA encryption algorithm. RSA is currently one of the most secure encryption algorithms and is widely used for secure data transmission.

  2. The SecureRandom.getInstanceStrong() method is used to get a strong instance of SecureRandom. This method is expected to return the most secure, highest-quality random numbers.

  3. The key size has been increased from 1024 to 2048 bits. A larger key size means more possible keys, making it harder for an attacker to guess the key.

  4. The cipher is now initialized with "RSA/ECB/OAEPWithSHA-256AndMGF1Padding" which is a more secure cipher algorithm. This algorithm uses RSA for encryption, ECB (Electronic Codebook) as the mode of operation, OAEP (Optimal Asymmetric Encryption Padding) with SHA-256 as the padding scheme, and MGF1 (Mask Generation Function) for generating a mask.

  5. The cipher text is now being printed as a UTF-8 string. This ensures that the encrypted text is properly displayed, regardless of the system's default character encoding.

By making these changes, the encryption process is now more secure and less likely to be compromised by an attacker.

References​

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