com.sun.faces.renderkit.ByteArrayGuard Maven / Gradle / Ivy
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package com.sun.faces.renderkit;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.NullCipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.faces.FacesException;
import java.security.Key;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.sun.faces.util.FacesLogger;
/**
* This utility class is to provide both encryption and
* decryption Ciphers to ResponseStateManager
* implementations wishing to provide encryption support.
*
* The algorithm used to encrypt byte array is AES with CBC.
*
* Original author Inderjeet Singh, J2EE Blue Prints Team. Modified to suit JSF
* needs.
*/
public final class ByteArrayGuard {
// Log instance for this class
private static final Logger LOGGER = FacesLogger.RENDERKIT.getLogger();
private static final int MAC_LENGTH = 32;
private static final int KEY_LENGTH = 128;
private static final int IV_LENGTH = 16;
private static final String KEY_ALGORITHM = "AES";
private static final String CIPHER_CODE = "AES/CBC/PKCS5Padding";
private static final String MAC_CODE = "HmacSHA256";
private Mac encryptMac;
private Mac decryptMac;
private SecretKey sk;
// ------------------------------------------------------------ Constructors
public ByteArrayGuard() {
try {
setupKeyAndMac();
} catch (Exception e) {
if (LOGGER.isLoggable(Level.SEVERE)) {
LOGGER.log(Level.SEVERE,
"Unexpected exception initializing encryption."
+ " No encryption will be performed.",
e);
}
System.err.println("ERROR: Initializing Ciphers");
}
}
// ---------------------------------------------------------- Public Methods
/**
* This method:
* Encrypts bytes using a cipher.
* Generates MAC for intialization vector of the cipher
* Generates MAC for encrypted data
* Returns a byte array consisting of the following concatenated together:
* |MAC for cnrypted Data | MAC for Init Vector | Encrypted Data |
* @param bytes The byte array to be encrypted.
* @return the encrypted byte array.
*/
public byte[] encrypt(byte[] bytes) {
byte[] securedata = null;
try {
// Generate IV
SecureRandom rand = new SecureRandom();
byte[] iv = new byte[16];
rand.nextBytes(iv);
IvParameterSpec ivspec = new IvParameterSpec(iv);
Cipher encryptCipher = Cipher.getInstance(CIPHER_CODE);
encryptCipher.init(Cipher.ENCRYPT_MODE, sk, ivspec);
encryptMac.update(iv);
// encrypt the plaintext
byte[] encdata = encryptCipher.doFinal(bytes);
byte[] macBytes = encryptMac.doFinal(encdata);
byte[] tmp = concatBytes(macBytes, iv);
securedata = concatBytes(tmp, encdata);
} catch (Exception e) {
if (LOGGER.isLoggable(Level.SEVERE)) {
LOGGER.log(Level.SEVERE,
"Unexpected exception initializing encryption."
+ " No encryption will be performed.",
e);
}
return null;
}
return securedata;
}
/**
* This method decrypts the provided byte array.
* The decryption is only performed if the regenerated MAC
* is the same as the MAC for the received value.
* @param bytes Encrypted byte array to be decrypted.
* @return Decrypted byte array.
*/
public byte[] decrypt(byte[] bytes) {
try {
// Extract MAC
byte[] macBytes = new byte[MAC_LENGTH];
System.arraycopy(bytes, 0, macBytes, 0, macBytes.length);
// Extract IV
byte[] iv = new byte[IV_LENGTH];
System.arraycopy(bytes, macBytes.length, iv, 0, iv.length);
// Extract encrypted data
byte[] encdata = new byte[bytes.length - macBytes.length - iv.length];
System.arraycopy(bytes, macBytes.length + iv.length, encdata, 0, encdata.length);
IvParameterSpec ivspec = new IvParameterSpec(iv);
Cipher decryptCipher = Cipher.getInstance(CIPHER_CODE);
decryptCipher.init(Cipher.DECRYPT_MODE, sk, ivspec);
// verify MAC by regenerating it and comparing it with the received value
decryptMac.update(iv);
decryptMac.update(encdata);
byte[] macBytesCalculated = decryptMac.doFinal();
if (Arrays.equals(macBytes, macBytesCalculated)) {
// continue only if the MAC was valid
// System.out.println("Valid MAC found!");
byte[] plaindata = decryptCipher.doFinal(encdata);
return plaindata;
} else {
System.err.println("ERROR: MAC did not verify!");
return null;
}
} catch (Exception e) {
System.err.println("ERROR: Decrypting:"+e.getCause());
return null; // Signal to JSF runtime
}
}
// --------------------------------------------------------- Private Methods
/**
* Generates secret key.
* Initializes MAC(s).
*/
private void setupKeyAndMac() {
try {
KeyGenerator kg = KeyGenerator.getInstance(KEY_ALGORITHM);
kg.init(KEY_LENGTH); // 256 if you're using the Unlimited Policy Files
sk = kg.generateKey();
encryptMac = Mac.getInstance(MAC_CODE);
decryptMac = Mac.getInstance(MAC_CODE);
encryptMac.init(sk);
decryptMac.init(sk);
} catch (Exception e) {
throw new FacesException(e);
}
}
/**
* This method concatenates two byte arrays
* @return a byte array of array1||array2
* @param array1 first byte array to be concatenated
* @param array2 second byte array to be concatenated
*/
private static byte[] concatBytes(byte[] array1, byte[] array2) {
byte[] cBytes = new byte[array1.length + array2.length];
try {
System.arraycopy(array1, 0, cBytes, 0, array1.length);
System.arraycopy(array2, 0, cBytes, array1.length, array2.length);
} catch(Exception e) {
throw new FacesException(e);
}
return cBytes;
}
}