I need to write a first program in one language that saves data in a text file, and write a second program in a second language to decrypt that file. The two languages in question don't include any crypto libraries, so I'm on my own.
Could someone recommend, point me to, or summarize a simple algorithm (pseudo code) that provides some level of basic encryption?
I don't have much experience in this area, but if you can summarize clearly in pseudo-code, I can implement it (don't assume prior knowledge).
It doesn't have to be bullet-proof, but just something that deters the user from understanding the text file. Something more secure than just a simple character-substitution (1 for 1), like perhaps a key that generates a random string used to XOR or similar complexity. I have no idea where to start.