Insecure encryption algorithm - AES
Need
Implementation of secure encryption algorithms
Context
- Usage of Java 8 for developing applications with enhanced features and performance improvements
- Usage of javax.crypto.Cipher for cryptographic operations
- Usage of IvParameterSpec for providing an initialization vector (IV) for cryptographic operations in Java
- Usage of javax.crypto.spec.SecretKeySpec for generating secret keys in cryptography
- Usage of java.util.Base64 for encoding and decoding data in Base64 format
Description
Non compliant code
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class VulnerableEncryption {
public static void main(String[] args) throws Exception {
String key = "1234567890123456"; // 128 bit key
String initVector = "RandomInitVector"; // 16 bytes IV
System.out.println(encrypt(key, initVector, "Hello World"));
}
public static String encrypt(String key, String initVector, String value) {
try {
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
return Base64.getEncoder().encodeToString(encrypted);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
}
In the provided code, the method encrypt is used to perform AES encryption in CBC mode with PKCS5 padding. The key and initialization vector (IV) are provided as string parameters and converted to the appropriate data types for use with the Cipher class.
The vulnerability lies in the use of the AES/CBC/PKCS5PADDING encryption mode. The Cipher Block Chaining (CBC) mode of operation has a few security concerns, especially when it is improperly implemented. For instance, it is vulnerable to padding oracle attacks. In addition, the use of PKCS5 padding can also lead to vulnerabilities such as padding oracle attacks.
Also, the key and the initialization vector (IV) are hardcoded in the main method which is a bad practice from a security perspective. The key and IV should be securely generated and stored, not hardcoded in the application. The hardcoded key and IV can be easily extracted from the application, rendering the encryption useless.
Moreover, the encryption method does not handle exceptions properly. It just prints the stack trace of the exception and returns null. This could lead to information leakage as the stack trace might contain sensitive information about the application. It also makes the application unpredictable as the method can return a valid encrypted string or null.
Furthermore, the code does not implement any form of authenticated encryption. This means that the integrity and authenticity of the encrypted data are not verified, which could lead to serious security issues.
Steps
- Replace the insecure encryption algorithm AES/CBC/PKCS5PADDING with a more secure algorithm such as AES/GCM or ChaCha20-Poly1305.
- Ensure that the encryption algorithm used provides authenticated encryption to protect against tampering.
- Use a secure key generation method to generate the encryption key.
- Use a secure random number generator to generate the initialization vector (IV).
- Ensure that the key and IV are securely stored and protected.
- Consider using a key management system to securely manage and rotate encryption keys.
- Update any other references to insecure encryption algorithms in the codebase.
Compliant code
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.SecretKey;
import javax.crypto.KeyGenerator;
import java.security.SecureRandom;
import java.util.Base64;
public class SecureEncryption {
public static void main(String[] args) throws Exception {
SecretKey key = generateKey(256);
byte[] initVector = generateIV(12); // GCM recommends 12 bytes IV
System.out.println(encrypt(key, initVector, "Hello World"));
}
public static SecretKey generateKey(int n) throws Exception {
// Use a secure key generation method
KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
keyGenerator.init(n);
return keyGenerator.generateKey();
}
public static byte[] generateIV(int n) {
// Use a secure random number generator
byte[] iv = new byte[n];
new SecureRandom().nextBytes(iv);
return iv;
}
public static String encrypt(SecretKey key, byte[] initVector, String value) {
try {
IvParameterSpec iv = new IvParameterSpec(initVector);
Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, key, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
return Base64.getEncoder().encodeToString(encrypted);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
}
The above code fixes the vulnerability by replacing the insecure encryption algorithm AES/CBC/PKCS5PADDING with a more secure algorithm AES/GCM.
AES/GCM provides authenticated encryption which protects against tampering.
The key is generated using a secure key generation method. The KeyGenerator class is used to generate a secret (symmetric) key suitable for a specified algorithm.
The initialization vector (IV) is generated using a secure random number generator. The SecureRandom class provides a cryptographically strong random number generator.
The key and IV are not hardcoded in the code, which is a good practice for security.
Please note that the key and IV should be securely stored and protected in a real-world application.
Also, consider using a key management system to securely manage and rotate encryption keys.
Finally, ensure to update any other references to insecure encryption algorithms in the codebase.