I'm making a data logger using Arduino Uno Rev3 and Adafruit datalogger shield.
I'm writing files to a SD card but I don't want them to read by anything other my program.
I'm thinking about writing my own text encoding so for example if I used an alphabet swap so A = Z to Z = A, then the string "hello world" would be swapped to "svool dliow".
I also want to be able to swap numbers so 0=9 to 9=0.
I will then write a program on my PC so the encoded files on the SD card can be decoded.
I understand that this "code" is easily cracked but I would like to know how to do this first before I move on to move complex stuff like real encoding and CRCs.
So does anyone know how to encode a string like this?