A question about encrypting file using AES

"JTL.zheng" <jtl.zheng@gmail.com>
8 Jan 2007 07:53:25 -0800
my code is:

  public static boolean enDeCrypt(String keyStr, File fin, File fout) {
    try {
     FileInputStream in = new FileInputStream(fin);
      FileOutputStream out = new FileOutputStream(fout);
      Cipher desCipher = Cipher.getInstance("AES");
                            new SecretKeySpec(keyStr.getBytes("UTF-8"),
      CipherOutputStream cos = new CipherOutputStream(out, desCipher);
      byte[] enBuffer = new byte[4096];
      int n;
      while ( (n = in.read(enBuffer)) != -1) {
        cos.write(enBuffer, 0, n);
    catch (Exception e) {
      return false;
    return true;

but it throw exception:
java.security.InvalidKeyException: Illegal key size or default
I used a 192-bit key

if I change the key's length, it will throw excepion:
java.security.InvalidKeyException: Invalid AES key length: 272
It seemed that it is not the problem about the length of the key

how can I fix it

Thank you very much in advance

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