---
_id: '302'
abstract:
- lang: eng
text: At ITCS 2013, Mahmoody, Moran and Vadhan [MMV13] introduce and construct publicly
verifiable proofs of sequential work, which is a protocol for proving that one
spent sequential computational work related to some statement. The original motivation
for such proofs included non-interactive time-stamping and universally verifiable
CPU benchmarks. A more recent application, and our main motivation, are blockchain
designs, where proofs of sequential work can be used – in combination with proofs
of space – as a more ecological and economical substitute for proofs of work which
are currently used to secure Bitcoin and other cryptocurrencies. The construction
proposed by [MMV13] is based on a hash function and can be proven secure in the
random oracle model, or assuming inherently sequential hash-functions, which is
a new standard model assumption introduced in their work. In a proof of sequential
work, a prover gets a “statement” χ, a time parameter N and access to a hash-function
H, which for the security proof is modelled as a random oracle. Correctness requires
that an honest prover can make a verifier accept making only N queries to H, while
soundness requires that any prover who makes the verifier accept must have made
(almost) N sequential queries to H. Thus a solution constitutes a proof that N
time passed since χ was received. Solutions must be publicly verifiable in time
at most polylogarithmic in N. The construction of [MMV13] is based on “depth-robust”
graphs, and as a consequence has rather poor concrete parameters. But the major
drawback is that the prover needs not just N time, but also N space to compute
a proof. In this work we propose a proof of sequential work which is much simpler,
more efficient and achieves much better concrete bounds. Most importantly, the
space required can be as small as log (N) (but we get better soundness using slightly
more memory than that). An open problem stated by [MMV13] that our construction
does not solve either is achieving a “unique” proof, where even a cheating prover
can only generate a single accepting proof. This property would be extremely useful
for applications to blockchains.
alternative_title:
- LNCS
author:
- first_name: Bram
full_name: Cohen, Bram
last_name: Cohen
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
citation:
ama: 'Cohen B, Pietrzak KZ. Simple proofs of sequential work. In: Vol 10821. Springer;
2018:451-467. doi:10.1007/978-3-319-78375-8_15'
apa: 'Cohen, B., & Pietrzak, K. Z. (2018). Simple proofs of sequential work
(Vol. 10821, pp. 451–467). Presented at the Eurocrypt: Advances in Cryptology,
Tel Aviv, Israel: Springer. https://doi.org/10.1007/978-3-319-78375-8_15'
chicago: Cohen, Bram, and Krzysztof Z Pietrzak. “Simple Proofs of Sequential Work,”
10821:451–67. Springer, 2018. https://doi.org/10.1007/978-3-319-78375-8_15.
ieee: 'B. Cohen and K. Z. Pietrzak, “Simple proofs of sequential work,” presented
at the Eurocrypt: Advances in Cryptology, Tel Aviv, Israel, 2018, vol. 10821,
pp. 451–467.'
ista: 'Cohen B, Pietrzak KZ. 2018. Simple proofs of sequential work. Eurocrypt:
Advances in Cryptology, LNCS, vol. 10821, 451–467.'
mla: Cohen, Bram, and Krzysztof Z. Pietrzak. *Simple Proofs of Sequential Work*.
Vol. 10821, Springer, 2018, pp. 451–67, doi:10.1007/978-3-319-78375-8_15.
short: B. Cohen, K.Z. Pietrzak, in:, Springer, 2018, pp. 451–467.
conference:
end_date: 2018-05-03
location: Tel Aviv, Israel
name: 'Eurocrypt: Advances in Cryptology'
start_date: 2018-04-29
date_created: 2018-12-11T11:45:42Z
date_published: 2018-05-29T00:00:00Z
date_updated: 2021-01-12T07:40:30Z
day: '29'
department:
- _id: KrPi
doi: 10.1007/978-3-319-78375-8_15
ec_funded: 1
intvolume: ' 10821'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2018/183.pdf
month: '05'
oa: 1
oa_version: Submitted Version
page: 451 - 467
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_status: published
publisher: Springer
publist_id: '7579'
quality_controlled: '1'
scopus_import: 1
status: public
title: Simple proofs of sequential work
type: conference
user_id: 2EBD1598-F248-11E8-B48F-1D18A9856A87
volume: 10821
year: '2018'
...