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If you want to derive separate keys for encryption (enck) and message authentication code (mack) from a master key using a Key Derivation Function (KDF), you can modify the previous example to derive two distinct keys. Here's an example:
```java
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.util.Arrays;
public class KDFEnckMackExample {
public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeySpecException {
// Replace with your master key
byte[] masterKey = hexStringToByteArray("yourMasterKeyInHex");
// Salt for KDF
byte[] salt = generateSalt();
// KDF parameters
int iterationCount = 10000; // You can adjust this based on your security requirements
int keyLength = 32; // for a 256-bit key
// Use KDF to derive encryption key (enck)
byte[] enck = deriveKey(masterKey, salt, iterationCount, keyLength);
// Use KDF to derive message authentication code key (mack)
byte[] mack = deriveKey(masterKey, salt, iterationCount, keyLength);
// Print the derived keys
System.out.println("Encryption Key (enck): " + byteArrayToHexString(enck));
System.out.println("MAC Key (mack): " + byteArrayToHexString(mack));
}
private static byte[] generateSalt() {
// Replace this with a secure method of generating salt
// For example, you can use SecureRandom:
// SecureRandom random = new SecureRandom();
// byte[] salt = new byte[16];
// random.nextBytes(salt);
// return salt;
return hexStringToByteArray("yourSaltInHex");
}
private static byte[] deriveKey(byte[] masterKey, byte[] salt, int iterationCount, int keyLength)
throws NoSuchAlgorithmException, InvalidKeySpecException {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
KeySpec spec = new PBEKeySpec(byteArrayToCharArray(masterKey), salt, iterationCount, keyLength * 8);
return factory.generateSecret(spec).getEncoded();
}
private static byte[] hexStringToByteArray(String hex) {
int len = hex.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
+ Character.digit(hex.charAt(i + 1), 16));
}
return data;
}
private static char[] byteArrayToCharArray(byte[] byteArray) {
char[] charArray = new char[byteArray.length];
for (int i = 0; i < byteArray.length; i++) {
charArray[i] = (char) (byteArray[i] & 0xFF);
}
return charArray;
}
private static String byteArrayToHexString(byte[] byteArray) {
StringBuilder result = new StringBuilder();
for (byte b : byteArray) {
result.append(String.format("%02X", b));
}
return result.toString();
}
}
```
In this example, the `deriveKey` method is called twice to derive two separate keys (`enck` and `mack`) from the master key. Ensure you replace "yourMasterKeyInHex" and "yourSaltInHex" with your actual master key and a random salt, respectively. Adjust the KDF parameters based on your security requirements.Editor is loading...
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