Now showing items 1-6 of 6

• #### The Complexity of Collision-Resistant Hashing ﻿

(2009-10-24)
A long-standing open problem on the intersection of Complexity Theory and Cryptography is whether the security of cryptographic primitives can be based on the worst-case hardness of NP. We show that, unless coNP $\subseteq$ ...
• #### Concurrent Zero Knowledge: Simplifications and Generalizations ﻿

(2008-05-07)
Few techniques for obtaining concurrent zero-knowledge exist; all require a complex and subtle analysis. We provide an arguably simpler and more general analysis of the oblivious simulation technique of Kilian and Petrank ...
• #### Constant-Round Concurrent Zero-Knowledge From Falsifiable Assumptions ﻿

(2012-10-02)
We present a constant-round concurrent zero-knowledge protocol for $\NP$. Our protocol is sound against uniform polynomial-time attackers, and relies on the existence of families of collision-resistant hash functions, and ...
• #### Limits of Security Reductions from Standard Assumptions ﻿

(2010-12-27)
We show that the security of some well-known cryptographic protocols, primitives and assumptions (e.g., the Schnorr identification scheme, commitments secure under adaptive selective-decommitment, the one-more'' discrete ...
• #### Multi-Verifier Signatures ﻿

(2009-08-15)
Multi-verifier signatures generalize traditional digital signatures to a secret-key setting. Just like digital signatures, these signatures are both transferable and secure under arbitrary (unbounded) adaptive chosen-message ...
• #### Settling the Round-Complexity of Non-Malleable Commitments ﻿

(2010-09-03)
We show \emph{unconditionally} that the existence of commitment schemes implies the existence of \emph{constant-round} non-malleable commitments; earlier protocol required additional assumptions such as collision resistant ...