## CryptoDB

### Joseph Bonneau

#### Publications

Year
Venue
Title
2022
ASIACRYPT
We introduce the short-lived proof, a non-interactive proof of knowledge with a novel feature: after a specified period of time, the proof is no longer convincing. This time-delayed loss of soundness happens "naturally" without further involvement from the prover or any third party. We propose definitions for short-lived proofs as well as the special case of short-lived signatures. We show several practical constructions built using verifiable delay functions (VDFs). The key idea in our approach is to allow any party to forge any proof by executing a large sequential computation. Some constructions achieve a stronger property called reusable forgeability in which one sequential computation allows forging an arbitrary number of proofs of different statements. We also introduces two novel types of VDFs, re-randomizable VDFs and zero-knowledge VDFs, which may be of independent interest. Our constructions for short-lived Sigma-protocols and signatures are practically efficient for provers and verifiers, adding a few hundred bytes of overhead and tens to hundreds of milliseconds of proving/verification time.
2018
CRYPTO
We study the problem of building a verifiable delay function (VDF). A $\text {VDF}$VDFrequires a specified number of sequential steps to evaluate, yet produces a unique output that can be efficiently and publicly verified. $\text {VDF}$VDFs have many applications in decentralized systems, including public randomness beacons, leader election in consensus protocols, and proofs of replication. We formalize the requirements for $\text {VDF}$VDFs and present new candidate constructions that are the first to achieve an exponential gap between evaluation and verification time.
2006
CHES

#### Coauthors

Arasu Arun (1)
Dan Boneh (1)
Benedikt Bünz (1)
Jeremy Clark (1)
Ben Fisch (1)
Ilya Mironov (1)