> mathematical impossibility of reversing some integer/mod calculation > There is a loss of information in mods and integer computations making them one-way

That's not correct. Trapdoor functions aren't one way because they destroy information, and if they were they wouldn't be very useful because you wouldn't be able to go back the other way (i.e. decrypt the text). You'd end up with many possible inputs for a given output, like a hash.