[crypto] crypto-protocols for trading card games

Here's an interesting problem: In the not too distant past there was a fad for collectible trading card games, the most famous of which was Magic, The Gathering (tm). These games combined the collecting and trading of baseball cards with traditional aspects of card playing. Cards were issued by a central authority/publisher (Wizards of the Coast in the case of MtG). Each player uses his or her own deck; cards that are not played remain secret; however the same deck mut be used in each round of a match. tournament games are adjudicated by an umpire. Design a set of crypto protocols to support the issuing, trading, and playing of such card games in real time (100ms compute time per move) Simon