Non-black-box simulation in the fully concurrent setting
Vipul Goyal · 2013
We present a new zero-knowledge argument protocol by relying on the non-black-box simulation technique of Barak (FOCS'01). Similar to the protocol of Barak, ours is public-coin, is based on the existence of collision-resistant hash functions, and, is not based on "rewinding techniques" but rather uses non-black-box simulation. However in contrast to the protocol of Barak, our protocol is secure even if there are any unbounded (polynomial) number of concurrent sessions. This gives us the first construction of public-coin concurrent zero-knowledge. Prior to our work, Pass, Tseng and Wikstrom (SIAM J. Comp. 2011) had shown that using black-box simulation, getting a construction for even public-coin parallel zero-knowledge is impossible.