#Pokerth 1.1.1. Offline#

Using recent advances in cryptocurrencies and blockchain techniques, Kumaresan et al. The two main challenges in deploying real world secure poker protocols lie in enforcing the distribution of rewards and dealing with misbehaving/aborting parties. Interestingly, Royale performs better than most previous works (that do not have composability guarantees), which we highlight through a detailed concrete complexity analysis and benchmarks from a prototype implementation. We remark that Royale also yields the first UC-secure poker protocol. Based on this formalism, we introduce Royale, the first UC-secure general card games which supports financial rewards/penalties enforcement. We both tackle the problem of constructing protocols for general card games and initiate a treatment of such protocols in the Universal Composability (UC) framework, introducing an ideal functionality that captures card games that use a set of core card operations. Even though folklore holds that poker protocols can be used to play any card game, this conjecture remains unproven and, in fact, does not hold for a number of protocols (including recent results). While many tailor made card game protocols are known, the vast majority of those lack three important features: mechanisms for distributing financial rewards and punishing cheaters, composability guarantees and flexibility, focusing on the specific game of poker. In order to do so, we build on blockchain-based techniques that leverage the power of stateful smart contracts to ensure fair protocol execution. Besides ensuring that the games are played correctly, our protocols support financial rewards and penalties enforcement, guaranteeing that winners receive their rewards and that cheaters get financially penalized. Moreover, in constructing highly efficient protocols, we introduce a new technique based on verifiable random functions for extending coin tossing, which is at the core of our constructions. We show that protocols for such games can be built from very lightweight primitives such as digital signatures and canonical random oracle commitments, yielding constructions that far outperform all known card game protocols in terms of communication, computational and round complexities. Basically, in these games, cards are chosen at random and then publicly advertised, allowing for players to publicly announce their actions (before or after cards are known). In this paper, we consider the case of games that do not require any secret state to be maintained (e.g.

This scenario poses many interesting technical challenges, which are addressed with cryptographic tools that introduce significant computational and communication overheads (e.g. While many cryptographic protocols for card games have been proposed, all of them focus on card games where players have some state that must be kept secret from each other, e.g closed cards and bluffs in Poker. Users play an active role in contributing to the unlinkability of messages: periodically, users initiate requests to AOT to receive dummy messages, such that an adversary cannot distinguish real and dummy requests. Through what we call a 'handshake' process, communicants can use the AOT protocol to establish shared secrets anonymously.

#Pokerth 1.1.1. Offline#

A receiver can receive their messages even if the receiver is offline when messages are ready. Each receiver checks the bulletin board, identifies tags, and receives the associated messages using OT. On a public bulletin board, Level-3 nodes publish tags associated with messages ready to be retrieved. The sender encrypts their payload and a tag, derived from a secret shared between the sender and receiver, with the public key of a Level-2 node and sends them to a Level-1 node. AOT comprises three levels of nodes, where nodes at each level perform a different function and can scale horizontally. Using OT to deliver messages helps AOT resist blending ($n-1$) attacks and helps AOT preserve receiver anonymity, even if a covert adversary controls all nodes in AOT.

We introduce AOT, an anonymous communication system based on mix network architecture that uses oblivious transfer (OT) to deliver messages.