1. // 'key' should be 32 bytes for AES256, will be null-padded otherwise
2.     char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
3.     bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
4.        
5. CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
6.                                      keyPtr, kCCKeySizeAES256,
7.                                      NULL /* initialization vector (optional) */,
8.                                      [self bytes], dataLength, /* input */
9.                                      buffer, bufferSize, /* output */
10.                                      &numBytesEncrypted);
11.        
12. private static final String AES_SECRET = "PreDefinedKey";
13.  
14. /**
15.  * Method for AES encryption
16.  * @param raw
17.  * @param plain
18.  * @return
19.  * @throws Exception
20.  */
21. private static byte[] encrypt(byte[] raw, byte[] plain) throws Exception {
22.     SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES/ECB/PKCS7Padding");
23.     Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding");
24.     cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
25.     byte[] encrypted = cipher.doFinal(plain);
26.     return encrypted;
27. }
28.  
29.  
30.  
31. /**
32.  * AES decryption
33.  * @param encryptMsg
34.  * @return
35.  * @throws Exception
36.  */
37. public static String AESDecrypt(String encryptMsg)
38.         throws Exception {          
39.     byte[] rawKey = getRawKey(AES_SECRET.getBytes());
40.     //byte[] enc = toByte(encryptMsg);
41.     byte[] enc = Base64.decode(encryptMsg, 0);
42.     byte[] result = decrypt(rawKey, enc);
43.     return new String(result);
44.  
45. }
46.  
47. /**
48.  * Method for AES decryption
49.  * @param raw
50.  * @param encrypted
51.  * @return
52.  * @throws Exception
53.  */
54. private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
55.     SecretKeySpec keySpec = new SecretKeySpec(raw, "AES/ECB/PKCS7Padding");
56.     Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding");
57.     cipher.init(Cipher.DECRYPT_MODE, keySpec);
58.     byte[] decrypted = cipher.doFinal(encrypted);
59.     return decrypted;
60.  
61. }
62.  
63. public static byte[] getRawKey(byte[] seed) throws Exception {
64.  
65.     KeyGenerator kgen = KeyGenerator.getInstance("AES");
66.     SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
67.     sr.setSeed(seed);
68.     //Init for 256bit AES key
69.     kgen.init(256);
70.     SecretKey secret = kgen.generateKey();
71.     //Get secret raw key
72.     byte[] raw = secret.getEncoded();
73.  
74.     return seed;
75.  
76. }
77.        
78. // zeros by default
79. byte[] rawKey = new byte[32];
80. // if you don't specify the encoding you might get weird results
81. byte[] keyBytes = AES_SECRET.getBytes("ASCII");
82. System.arraycopy(keyBytes, 0, rawKey, 0, keyBytes.length);
83. SecretKey key = new SecretKeySpec(rawKey, "AES");
84. Cipher cipher = ...
85. // rest of your decryption code

http://pastebin.com/UQB7xEXY