I'm designing a really light-weight wireless network and want to include a bit of encryption. Just a bit more than simply obscuring. All of the data will be ASCII (numbers, mostly). So each byte will be between 0x01 and 0x7F (inclusive). One possibility is to simply add a number (that might change from message to message in a known pattern) between 0 and 0x7F to each byte (same number applied to all bytes in the message).. That is sort of the minimal obscuration. I guess what I am looking for is just one step above that.