DissidentX is an encryption system designed to hide secret messages "in plain sight" within normal non-secret files, a process known as steganography. It was created by Bram Cohen, who also originated BitTorrent.
DissidentX is an open-source project implemented in Python, which has several methods of inserting encrypted messages into other files, including putting extra spaces at the ends of lines of text files. This is an inefficient way of encoding information; a much larger volume of unrelated plaintext is needed compared to the "payload" of the secret message. However, the technique adds some obscurity to the security by making it less obvious that there is even any secret message being transmitted in the first place; once somebody does figure this out, they still need the secret key to decode the message.