---
_id: '83'
abstract:
- lang: eng
  text: "A proof system is a protocol between a prover and a verifier over a common
    input in which an honest prover convinces the verifier of the validity of true
    statements. Motivated by the success of decentralized cryptocurrencies, exemplified
    by Bitcoin, the focus of this thesis will be on proof systems which found applications
    in some sustainable alternatives to Bitcoin, such as the Spacemint and Chia cryptocurrencies.
    In particular, we focus on proofs of space and proofs of sequential work.\r\nProofs
    of space (PoSpace) were suggested as more ecological, economical, and egalitarian
    alternative to the energy-wasteful proof-of-work mining of Bitcoin. However, the
    state-of-the-art constructions of PoSpace are based on sophisticated graph pebbling
    lower bounds, and are therefore complex. Moreover, when these PoSpace are used
    in cryptocurrencies like Spacemint, miners can only start mining after ensuring
    that a commitment to their space is already added in a special transaction to
    the blockchain. Proofs of sequential work (PoSW) are proof systems in which a
    prover, upon receiving a statement x and a time parameter T, computes a proof
    which convinces the verifier that T time units had passed since x was received.
    Whereas Spacemint assumes synchrony to retain some interesting Bitcoin dynamics,
    Chia requires PoSW with unique proofs, i.e., PoSW in which it is hard to come
    up with more than one accepting proof for any true statement. In this thesis we
    construct simple and practically-efficient PoSpace and PoSW. When using our PoSpace
    in cryptocurrencies, miners can start mining on the fly, like in Bitcoin, and
    unlike current constructions of PoSW, which either achieve efficient verification
    of sequential work, or faster-than-recomputing verification of correctness of
    proofs, but not both at the same time, ours achieve the best of these two worlds."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Hamza M
  full_name: Abusalah, Hamza M
  id: 40297222-F248-11E8-B48F-1D18A9856A87
  last_name: Abusalah
citation:
  ama: Abusalah HM. Proof systems for sustainable decentralized cryptocurrencies.
    2018. doi:<a href="https://doi.org/10.15479/AT:ISTA:TH_1046">10.15479/AT:ISTA:TH_1046</a>
  apa: Abusalah, H. M. (2018). <i>Proof systems for sustainable decentralized cryptocurrencies</i>.
    Institute of Science and Technology Austria. <a href="https://doi.org/10.15479/AT:ISTA:TH_1046">https://doi.org/10.15479/AT:ISTA:TH_1046</a>
  chicago: Abusalah, Hamza M. “Proof Systems for Sustainable Decentralized Cryptocurrencies.”
    Institute of Science and Technology Austria, 2018. <a href="https://doi.org/10.15479/AT:ISTA:TH_1046">https://doi.org/10.15479/AT:ISTA:TH_1046</a>.
  ieee: H. M. Abusalah, “Proof systems for sustainable decentralized cryptocurrencies,”
    Institute of Science and Technology Austria, 2018.
  ista: Abusalah HM. 2018. Proof systems for sustainable decentralized cryptocurrencies.
    Institute of Science and Technology Austria.
  mla: Abusalah, Hamza M. <i>Proof Systems for Sustainable Decentralized Cryptocurrencies</i>.
    Institute of Science and Technology Austria, 2018, doi:<a href="https://doi.org/10.15479/AT:ISTA:TH_1046">10.15479/AT:ISTA:TH_1046</a>.
  short: H.M. Abusalah, Proof Systems for Sustainable Decentralized Cryptocurrencies,
    Institute of Science and Technology Austria, 2018.
corr_author: '1'
date_created: 2018-12-11T11:44:32Z
date_published: 2018-09-05T00:00:00Z
date_updated: 2025-09-22T09:24:16Z
day: '05'
ddc:
- '004'
degree_awarded: PhD
department:
- _id: KrPi
doi: 10.15479/AT:ISTA:TH_1046
ec_funded: 1
file:
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  date_created: 2019-04-09T06:43:41Z
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has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '59'
project:
- _id: 258C570E-B435-11E9-9278-68D0E5697425
  call_identifier: FP7
  grant_number: '259668'
  name: Provable Security for Physical Cryptography
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '682815'
  name: Teaching Old Crypto New Tricks
publication_identifier:
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '7971'
pubrep_id: '1046'
related_material:
  record:
  - id: '559'
    relation: part_of_dissertation
    status: public
  - id: '1236'
    relation: part_of_dissertation
    status: public
  - id: '1235'
    relation: part_of_dissertation
    status: public
  - id: '1229'
    relation: part_of_dissertation
    status: public
status: public
supervisor:
- first_name: Krzysztof Z
  full_name: Pietrzak, Krzysztof Z
  id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
  last_name: Pietrzak
  orcid: 0000-0002-9139-1654
title: Proof systems for sustainable decentralized cryptocurrencies
type: dissertation
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2018'
...