package org.jboss.resteasy.jose.jwe.crypto;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.engines.AESEngine;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.security.NoSuchAlgorithmException;
/**
* AES encryption, decryption and key generation methods. Uses the
* BouncyCastle.org provider.
*
* @author Vladimir Dzhuvinov
* @version $version$ (2013-05-06)
*/
class AES
{
/**
* Generates an AES key of the specified length.
*
* @param keyBitLength The key length, in bits.
*
* @return The AES key.
*
* @throws RuntimeException If an AES key couldn't be generated.
*/
public static SecretKey generateKey(final int keyBitLength)
throws RuntimeException {
KeyGenerator keygen;
try {
keygen = KeyGenerator.getInstance("AES", new BouncyCastleProvider());
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e.getMessage(), e);
}
keygen.init(keyBitLength);
return keygen.generateKey();
}
/**
* Creates a new AES cipher.
*
* @param secretKey The AES key. Must not be {@code null}.
* @param forEncryption If {@code true} creates an AES encryption
* cipher, else creates an AES decryption
* cipher.
*
* @return The AES cipher.
*/
public static AESEngine createCipher(final SecretKey secretKey,
final boolean forEncryption) {
AESEngine cipher = new AESEngine();
CipherParameters cipherParams = new KeyParameter(secretKey.getEncoded());
cipher.init(forEncryption, cipherParams);
return cipher;
}
/**
* Prevents public instantiation.
*/
private AES() { }
}