e2ee algorithms are now pluggable so if you want to roll your own algorithm or do something like swap_bytes(rabbit(left_shift(3,triple_aes256(right_shift(base64(text)))))) - go for it. As long as the person at the other end can reverse it, you can do pretty much whatever you want. I'd like to see the NSA crack that one - especially if the algorithm was called something like "dishwasher" or something which didn't provide a lot of clues.