Invalid AES key length: 128 bytes?

Question

I get java.security.InvalidKeyException: Invalid AES key length: 128 bytes on my line

 CIPHER.init(Cipher.ENCRYPT_MODE, keySpec); 

with CIPHER

 Cipher CIPHER = Cipher.getInstance("AES"); 

and keySpec

 SecretKeySpec keySpec = new SecretKeySpec(key, "AES"); 

this key is 128 byte[] , I went through the Diffie-Hellman key exchange (although it doesn't matter where I got it, right?), the key completely filled with non-zero bytes

Why Cipher.init(...) complain that the key is the wrong length? This web page clearly indicates that a key of length 128 is supported.

What am I missing?

Answer 1

I think you need a 128-bit key here for the AES algorithm, not 128 bytes. To convert the long key to the desired length, you can try something like a password-based key output function. For example, see PBKDF2.

Answer 2

The AES algorithm allows 128, 192 or 256 bit key lengths. which is 16, 24 or 32 bytes. The length of your keys should be 16, 24 or 32 bytes.