Single-Shuffle Card-Based Protocols for Any Boolean Circuit with Six Cards per Gate

Card-based protocols perform secure computation using physical playing cards, and their efficiency is primarily evaluated by two metrics: the number of cards and the number of shuffles. In this paper, we present three new card-based protocols that reduce the number of cards. The first protocol supports any Boolean circuit and decreases the number of cards. The second protocol extends the first to a committed-format version, while the third is specialized for Boolean circuits without a branched input, achieving an even smaller number of cards. All the proposed protocols are based on Yao’s garbled-circuit framework, similar to previous single-shuffle card-based protocols. Our main contribution is a novel encoding method that represents the truth table of each Boolean gate with fewer cards than existing schemes. Consequently, our protocols require only six cards per gate in a single-shuffle execution, providing a significant improvement in efficiency over prior work. Furthermore, by incorporating the card-based free-XOR introduced by Manabe–Shinagawa, we can further reduce the number of cards in certain configurations.