🚀 go-pugleaf

I need a function that takes in any variable-length message M of m bits,
and a secret key K of k bits, and produces a fixed length bit pattern of
s bits.

Requirements:

1. Given any number of M's and their corresponding s bit patterns,
   it should be computationally difficult to compute the s bit pattern
   of any new message. (difficult enough to exhaust $200 before a solution
   is found)

2. The function should be simple to implement (much simpler and faster than
   RSA and DES).

Note:

This function could be called a hashing or compressed encoding function that
acts as a trapdoor or one-way function.


Any suggestions or pointers?

Ra'ad