Securetrade: a secure protocol based on transferable E-cash for exchanging cards in P2P trading card games.

• Autor(a) principal: Marcos Vinicius Maciel da Silva
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://doi.org/10.11606/D.3.2016.tde-22092016-113539

Trading card games (TCG) are distinct from traditional card games mainly because, in the former, the cards are not shared among players in a match. Instead, users play with the cards they own (e.g., that have been purchased or traded with other players), which correspond to a subset of all cards produced by the game provider. Even though most computer-based TCGs rely on a trusted third-party (TTP) for preventing cheating during trades, allowing them to securely do so in the absence of such entity, as in a Peer-to-Peer (P2P) scenario, remains a challenging task. Potential solutions for this challenge can be based on e-cash protocols, but not without adaptations, as those scenarios display different requirements: for example, TCGs should allow users to play with the cards under their possession, not only to be able to pass those cards over as with digital coins. In this work, we present and discuss the security requirements for allowing cards to be traded in TCGs and how they relate to e-cash. We then propose a concrete and efficient TTP-free protocol for trading cards in a privacy-preserving manner. The construction is based on a secure transferable e-cash protocol and on a P-signature scheme converted to the asymmetric pairing setting. According to our experimental results, the proposed protocol is quite efficient for use in practice: an entire deck is stored in less than 5 MB, while it takes a few seconds to be prepared for a match; the verification of the cards, on its turn, takes less time than an usual match, and can be performed in background while the game is played.