Extension of a password hashing algorithm using Fibonacci
Ignore the integer overflow issue I mentioned in a comment, for a moment.

I don't see how this adds any security.

For all $n&gt;2$, the function you are calling Fibonacci is one-to-one, and since $n&lt;256$, you could easily build a lookup table without much memory to invert the function.

Therefore, to break this, all one has to do is invert the Fibonacci related stuff (not too hard), then attempt to break the SHA-1 hash. So, it isn't much harder than just breaking the SHA-1 hash by itself.


  if not, if you can give me some suggestions


Well, that would just take all the fun out of your class, now wouldn't it. That said, look into functions like PBKDF2 and bcrypt to see how they make things harder.

The integer overflow issue could make it harder to invert the function. Though, likely not in a cryptographically secure manner. But to really say no, it doesn't add security, I'd have to check how the integer overflow problem manifests itself.