java - 如何生成 256 位 AES key

Question

这个问题已经有答案了:

InvalidKeyException Illegal key size (6 个回答)

已关闭 6 年前。

为了生成 256 位的 AES key ，我编写了以下代码:

KeyGenerator keyGen;

try {
  keyGen = KeyGenerator.getInstance("AES");
  keyGen.init(256);
  SecretKey secretKey = keyGen.generateKey();
  return secretKey;    
}
catch (Exception e) {
  e.printStackTrace();
  return null;
}

我的加密方法是:

  private byte[] aes256Encode(SecretKey key, IvParameterSpec iv, String message) throws InvalidKeyException,
      InvalidAlgorithmParameterException,
      NoSuchAlgorithmException, NoSuchPaddingException,
      IllegalBlockSizeException, BadPaddingException 
  {
    Cipher cipher = Cipher.getInstance("AES/CFB/PKCS5Padding");
    cipher.init(Cipher.ENCRYPT_MODE, key, iv);
    byte[] encrypted = cipher.doFinal(message.getBytes());
    return encrypted;
  }

IV的生成方法是:

  private IvParameterSpec generateAESIV() {
    // build the initialization vector (randomly).
    SecureRandom random = new SecureRandom();
    byte iv[] = new byte[16];//generate random 16 byte long
    random.nextBytes(iv);
    IvParameterSpec ivspec = new IvParameterSpec(iv);
    return ivspec;
  }

但是在加密时，它抛出以下错误:

Exception in thread "main" java.security.InvalidKeyException: Illegal key size
    at javax.crypto.Cipher.checkCryptoPerm(Cipher.java:1039)
    at javax.crypto.Cipher.implInit(Cipher.java:805)
    at javax.crypto.Cipher.chooseProvider(Cipher.java:864)
    at javax.crypto.Cipher.init(Cipher.java:1396)
    at javax.crypto.Cipher.init(Cipher.java:1327)

有人可以指出我在这里犯的错误吗？

Answer 1

您更新了 JCE jar 吗？

http://www.oracle.com/technetwork/java/javase/downloads/jce-7-download-432124.html

Java 出厂时默认为 128 位。看一下然后告诉我