Could you explain your requirements?
1. To prove that a cryptographic function is safe, it is often compared to a random oracle. Do you need a good linear feedback shift register (random oracle) ?
or
2. Do you need a distinguishing attack (a form of cryptanalysis on data encrypted by a cipher that allows an attacker to distinguish the encrypted data from random data) for your cipher algorithm?
I could develop a solution in C, Java or Python.