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Insecure encryption algorithm - Default encryption

Need​

Implementation of customer-controlled keys for encryption

Context​

  • Usage of Java for building cross-platform applications
  • Usage of javax.crypto.Cipher for encryption and decryption operations
  • Usage of javax.crypto.spec.SecretKeySpec for generating a secret key specification
  • Usage of java.security.Key for cryptographic key management and operations
  • 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.SecretKeySpec;
import java.security.Key;
import java.util.Base64;

public class EncryptionUtil {
    private static final String ALGORITHM = "AES";
    private static final byte[] keyValue = 
        new byte[] { 'T', 'h', 'i', 's', 'I', 's', 'A', 'S', 'e', 'c', 'r', 'e', 't', 'K', 'e', 'y' };

    public static String encrypt(String valueToEnc) throws Exception {
        Key key = generateKey();
        Cipher c = Cipher.getInstance(ALGORITHM);
        c.init(Cipher.ENCRYPT_MODE, key);
        byte[] encValue = c.doFinal(valueToEnc.getBytes());
        String encryptedValue = Base64.getEncoder().encodeToString(encValue);
        return encryptedValue;
    }

    private static Key generateKey() throws Exception {
        Key key = new SecretKeySpec(keyValue, ALGORITHM);
        return key;
    }
}

This code represents an insecure encryption algorithm vulnerability. In this example, the Java Cryptography Extension (JCE) is used to encrypt data using a hard-coded key and the AES algorithm.

The EncryptionUtil class has two methods: encrypt and generateKey.

The encrypt method takes a string to be encrypted, generates a key, initializes a cipher for encryption using the key, encrypts the string, and returns the encrypted string.

The generateKey method creates a key from a hard-coded byte array and the AES algorithm.

The vulnerability lies in the use of a hard-coded key for encryption. This is insecure because if an attacker gains access to the source code, they can easily find the key and decrypt any data that was encrypted using this key.

Further, this code does not use the Amazon Key Management Service (KMS) for managing encryption keys, which is a best practice for AWS-based applications. KMS provides additional security features such as automatic key rotation, audit logging, and integration with AWS Identity and Access Management (IAM).

It is recommended to use Customer Managed Keys (CMKs) in KMS instead of hard-coded keys. CMKs give you more control over the cryptographic keys used to encrypt and decrypt your data.

Steps​

  • Replace the use of the default encryption algorithm with a more secure algorithm.
  • Use a strong and secure encryption algorithm, such as AES-256.
  • Generate a random and secure encryption key instead of using a hardcoded key.
  • Consider using a key management service, such as Amazon Key Management Service (KMS), to securely manage and store encryption keys.
  • Ensure that the encryption key is properly protected and securely stored.
  • Implement proper key rotation and key management practices to enhance security.
  • Regularly review and update the encryption implementation to address any new vulnerabilities or weaknesses.

Compliant code​

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.SecureRandom;
import java.util.Base64;

public class EncryptionUtil {
    private static final String ALGORITHM = "AES";
    private static final int KEY_SIZE = 256;

    public static String encrypt(String valueToEnc) throws Exception {
        SecretKey secretKey = generateKey();
        Cipher c = Cipher.getInstance(ALGORITHM);
        c.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] encValue = c.doFinal(valueToEnc.getBytes());
        String encryptedValue = Base64.getEncoder().encodeToString(encValue);
        return encryptedValue;
    }

    private static SecretKey generateKey() throws Exception {
        KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM);
        keyGenerator.init(KEY_SIZE, new SecureRandom());
        SecretKey secretKey = keyGenerator.generateKey();
        return secretKey;
    }
}

The updated code now uses a more secure encryption algorithm, AES-256, instead of the default AES. The key size has been increased to 256 bits to match the algorithm.

The generateKey() method has been updated to generate a random and secure encryption key instead of using a hardcoded key. This is done using the KeyGenerator class and the SecureRandom class from the Java Cryptography Architecture (JCA).

The KeyGenerator instance is initialized with the key size and a new instance of SecureRandom. This ensures that the generated key is random and secure. The generateKey() method then generates a SecretKey which is used for the encryption.

The encrypt() method remains largely the same, but now uses the generated SecretKey for encryption.

Please note that this code does not include key management practices such as key rotation and secure key storage. For production use, consider using a key management service, such as Amazon Key Management Service (KMS), to securely manage and store encryption keys. Regularly review and update the encryption implementation to address any new vulnerabilities or weaknesses.

References​

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