I'm new to cryptography and I am trying to figure out an equation that convert any big number to a smaller one and another one that reverse the operation to get the same big number again!
The problem here is every equation I use works fine with some numbers and others no.
I want one that works with all like:
Encrypted = Data - key Data = Encrypted + key
But of course I want it to be more difficult :)
Can any one help me with that ?