An epistemic characterization of zero knowledge

Halpern, Moses and Tuttle presented a definition of interactive proofs using a notion they called practical knowledge, but left open the question of finding an epistemic formula that completely characterizes zero knowledge; that is, a formula that holds iff a proof is zero knowledge. We present such a formula, and show that it does characterize zero knowledge. Moreover, we show that variants of the formula characterize variants of zero knowledge such as concurrent zero knowledge [Dwork, Naor, and Sahai 1998] and proofs of knowledge [Feige, Fiat, and Shamir 1987; Tompa and Woll 1987]. 

• Type: Conference
• Year: 2009
• Where: TARK
• Authors: Joseph Y. Halpern, Rafael Pass, Vasumathi Raman
• Keywords: Artificial Intelligence, Concurrent Zero Knowledge, Practical Knowledge, TARK 2009, Zero Knowledge