[Movie] This Famous Medieval Book May Be a Hoax

[Mauro]

If I encode a character using the combination of the word length and the second character in the word (say, qOkedy is O-6 or S, cHedy is H-5 or A, oTey is T-4 or Y, pOchey is O-6 or S again), this is non-deterministic, but perfectly reversible. 

Hmm sorry but I don't understand. It seems to me your encoding method is deterministic (no random numbers are involved) but non-reversible (is O-6 'qokedy' or 'qokain'?)