Bounded-concurrent secure multi-party computation with a dishonest majority
STOC '04 Proceedings of the thirty-sixth annual ACM symposium on Theory of computing
Journal of the ACM (JACM)
Generic and Practical Resettable Zero-Knowledge in the Bare Public-Key Model
EUROCRYPT '07 Proceedings of the 26th annual international conference on Advances in Cryptology
Composability and On-Line Deniability of Authentication
TCC '09 Proceedings of the 6th Theory of Cryptography Conference on Theory of Cryptography
Efficient Concurrent npoly(logn)-Simulatable Argument of Knowledge
ISPEC '09 Proceedings of the 5th International Conference on Information Security Practice and Experience
The round-complexity of black-box zero-knowledge: a combinatorial characterization
TCC'08 Proceedings of the 5th conference on Theory of cryptography
On constant-round concurrent zero-knowledge
TCC'08 Proceedings of the 5th conference on Theory of cryptography
Concurrent knowledge extraction in the public-key model
ICALP'10 Proceedings of the 37th international colloquium conference on Automata, languages and programming
TCC'11 Proceedings of the 8th conference on Theory of cryptography
Concurrent zero-knowledge with timing, revisited
Theoretical Computer Science
Parallel and concurrent security of the HB and HB+ protocols
EUROCRYPT'06 Proceedings of the 24th annual international conference on The Theory and Applications of Cryptographic Techniques
Concurrent zero knowledge without complexity assumptions
TCC'06 Proceedings of the Third conference on Theory of Cryptography
Resettable statistical zero knowledge
TCC'12 Proceedings of the 9th international conference on Theory of Cryptography
Public-Coin concurrent zero-knowledge in the global hash model
TCC'13 Proceedings of the 10th theory of cryptography conference on Theory of Cryptography
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We show that any concurrent zero-knowledge protocol for a nontrivial language (i.e., for a language outside ${\cal BPP}$), whose security is proven via black-box simulation, must use at least $\tilde\Omega(\log n)$ rounds of interaction. This result achieves a substantial improvement over previous lower bounds and is the first bound to rule out the possibility of constant-round concurrent zero-knowledge when proven via black-box simulation. Furthermore, the bound is polynomially related to the number of rounds in the best known concurrent zero-knowledge protocol for languages in ${\cal NP}$ (which is established via black-box simulation).