Generate random key for encryption module

Hi all,

I have defined a custom PI module for encrypt and decrypt fields in a xml,

For encrypt and decrypt the fields I'm using a varible=key array byte[], I need this varible is diferent in the several executions, for this reason I have the next code suurce where I asiggn a value to the variable Key with a random:

private  byte[] secretKey=new byte[8];

Random random= new Random();

random.setSeed(System.currentTimeMillis());

random.nextBytes(secretKey);

but the problem is that always have the same coding in the several executions,I dont understand where is the problem.

Thanks and best regards.

Mónica