Uses GNUnet's crypto library to generate keys. Biggest problem I've found is fraud potential, the mint operator can run a fractional reserve since it relies on "government authorities doing regular audits" and also that it touts turning Mastercard/Visa into Taler. Carders will become their own merchants, card a mint to get Taler and then cash it all out before anybody knows what happened. You also can't transfer Taler p2p, all transactions go through the mint to prevent "black markets".

Edit: Uses this API http://api.taler.net/ plus seems to have future GNUnet compatibility built into it's system for payments over it.