Well, OpenPGP works, and it is not terribly complicated. But yes, UTF-8 is a huge can of worms. (An accepted solution for this problem is obligatory "canonical

Well, OpenPGP works, and it is not terribly complicated. But yes, UTF-8 is a huge can of worms. (An accepted solution for this problem is obligatory "canonicalization" step - transforming the message into agreed canonical format before transmitting it. Still viewable and editable by text editors, no need to worry about parsing errors. Canonicalization step can still be error-prone, but the attack surface is much less than every possible parser in the world.)