1. Secure Poker Post PC project 2002

2. Motivation Games have been pushing computer industry Many people carry gadgets, but hardly a pack of cards. (even during a hike :-) Why should you trust the opponent’s computer?

3. Casino without dealer? It will be nice to deal pack of cards without a dealer. So who will deal the pack? –Two packs solution –One pack solution

4. Pack per player solution Player ‘A’ is to receive a card ‘A’ shuffles his pack, but does not show the shuffled pack to his opponent ‘B’ ‘B’ chooses a random number #i. ‘A’ picks up card #i from the pack. How ‘B’ could prevent ‘A’ from cheating?

5. Commitment and Verification At the begging of the game ‘A’ sends a commitment to his shuffled pack. At the end of the game ‘A’ sends the shuffled pack to ‘B’. ‘B’ verifies that commitment is correct. Secure hash (one-way function) is used to calculate the commitment.

6. One pack solution Player A Shuffles pack Encrypts (key1) each card in pack and sends the pack to ‘B’ Decrypts(key1) a random card and sends it to ‘B’ Player B Shuffles encrypted pack and encrypts (key2) the pack and sends it to ‘A’ Decrypts (key2) the card and uses it

7. Illustration

8. Real Demonstration

9. Requirements Network Memory CPU Battery

10. Other usages of this protocol Casting lots and playing lotteries Games requiring commitment (e.g. scissors, stone and knife or זוג הפרד) e-commerce e-voting

11. Conclusions Cryptographic solution are not always applicable. May be we need a special hardware, or a trusted dealer, or just a change of the rules? Technology is advancing and games are increasingly available on PDA PDA is going to be secure platform! Development is really doable !