---
_id: '10324'
abstract:
- lang: eng
  text: Off-chain protocols (channels) are a promising solution to the scalability
    and privacy challenges of blockchain payments. Current proposals, however, require
    synchrony assumptions to preserve the safety of a channel, leaking to an adversary
    the exact amount of time needed to control the network for a successful attack.
    In this paper, we introduce Brick, the first payment channel that remains secure
    under network asynchrony and concurrently provides correct incentives. The core
    idea is to incorporate the conflict resolution process within the channel by introducing
    a rational committee of external parties, called wardens. Hence, if a party wants
    to close a channel unilaterally, it can only get the committee’s approval for
    the last valid state. Additionally, Brick provides sub-second latency because
    it does not employ heavy-weight consensus. Instead, Brick uses consistent broadcast
    to announce updates and close the channel, a light-weight abstraction that is
    powerful enough to preserve safety and liveness to any rational parties. We formally
    define and prove for Brick the properties a payment channel construction should
    fulfill. We also design incentives for Brick such that honest and rational behavior
    aligns. Finally, we provide a reference implementation of the smart contracts
    in Solidity.
acknowledgement: We would like to thank Kaoutar Elkhiyaoui for her valuable feedback
  as well as Jakub Sliwinski for his impactful contribution to this work.
alternative_title:
- LNCS
article_processing_charge: No
arxiv: 1
author:
- first_name: Zeta
  full_name: Avarikioti, Zeta
  last_name: Avarikioti
- first_name: Eleftherios
  full_name: Kokoris Kogias, Eleftherios
  id: f5983044-d7ef-11ea-ac6d-fd1430a26d30
  last_name: Kokoris Kogias
- first_name: Roger
  full_name: Wattenhofer, Roger
  last_name: Wattenhofer
- first_name: Dionysis
  full_name: Zindros, Dionysis
  last_name: Zindros
citation:
  ama: 'Avarikioti Z, Kokoris Kogias E, Wattenhofer R, Zindros D. Brick: Asynchronous
    incentive-compatible payment channels. In: <i>25th International Conference on
    Financial Cryptography and Data Security</i>. Vol 12675. Springer Nature; 2021:209-230.
    doi:<a href="https://doi.org/10.1007/978-3-662-64331-0_11">10.1007/978-3-662-64331-0_11</a>'
  apa: 'Avarikioti, Z., Kokoris Kogias, E., Wattenhofer, R., &#38; Zindros, D. (2021).
    Brick: Asynchronous incentive-compatible payment channels. In <i>25th International
    Conference on Financial Cryptography and Data Security</i> (Vol. 12675, pp. 209–230).
    Virtual: Springer Nature. <a href="https://doi.org/10.1007/978-3-662-64331-0_11">https://doi.org/10.1007/978-3-662-64331-0_11</a>'
  chicago: 'Avarikioti, Zeta, Eleftherios Kokoris Kogias, Roger Wattenhofer, and Dionysis
    Zindros. “Brick: Asynchronous Incentive-Compatible Payment Channels.” In <i>25th
    International Conference on Financial Cryptography and Data Security</i>, 12675:209–30.
    Springer Nature, 2021. <a href="https://doi.org/10.1007/978-3-662-64331-0_11">https://doi.org/10.1007/978-3-662-64331-0_11</a>.'
  ieee: 'Z. Avarikioti, E. Kokoris Kogias, R. Wattenhofer, and D. Zindros, “Brick:
    Asynchronous incentive-compatible payment channels,” in <i>25th International
    Conference on Financial Cryptography and Data Security</i>, Virtual, 2021, vol.
    12675, pp. 209–230.'
  ista: 'Avarikioti Z, Kokoris Kogias E, Wattenhofer R, Zindros D. 2021. Brick: Asynchronous
    incentive-compatible payment channels. 25th International Conference on Financial
    Cryptography and Data Security. FC: Financial Cryptography, LNCS, vol. 12675,
    209–230.'
  mla: 'Avarikioti, Zeta, et al. “Brick: Asynchronous Incentive-Compatible Payment
    Channels.” <i>25th International Conference on Financial Cryptography and Data
    Security</i>, vol. 12675, Springer Nature, 2021, pp. 209–30, doi:<a href="https://doi.org/10.1007/978-3-662-64331-0_11">10.1007/978-3-662-64331-0_11</a>.'
  short: Z. Avarikioti, E. Kokoris Kogias, R. Wattenhofer, D. Zindros, in:, 25th International
    Conference on Financial Cryptography and Data Security, Springer Nature, 2021,
    pp. 209–230.
conference:
  end_date: 2021-03-05
  location: Virtual
  name: 'FC: Financial Cryptography'
  start_date: 2021-03-01
date_created: 2021-11-21T23:01:29Z
date_published: 2021-10-23T00:00:00Z
date_updated: 2023-08-14T12:59:58Z
day: '23'
department:
- _id: ElKo
doi: 10.1007/978-3-662-64331-0_11
external_id:
  arxiv:
  - '1905.11360'
  isi:
  - '000712016200011'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/1905.11360
month: '10'
oa: 1
oa_version: Preprint
page: 209-230
publication: 25th International Conference on Financial Cryptography and Data Security
publication_identifier:
  eisbn:
  - 978-3-662-64331-0
  eissn:
  - 1611-3349
  isbn:
  - 9-783-6626-4330-3
  issn:
  - 0302-9743
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Brick: Asynchronous incentive-compatible payment channels'
type: conference
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: '12675 '
year: '2021'
...
---
_id: '10325'
abstract:
- lang: eng
  text: Since the inception of Bitcoin, a plethora of distributed ledgers differing
    in design and purpose has been created. While by design, blockchains provide no
    means to securely communicate with external systems, numerous attempts towards
    trustless cross-chain communication have been proposed over the years. Today,
    cross-chain communication (CCC) plays a fundamental role in cryptocurrency exchanges,
    scalability efforts via sharding, extension of existing systems through sidechains,
    and bootstrapping of new blockchains. Unfortunately, existing proposals are designed
    ad-hoc for specific use-cases, making it hard to gain confidence in their correctness
    and composability. We provide the first systematic exposition of cross-chain communication
    protocols. We formalize the underlying research problem and show that CCC is impossible
    without a trusted third party, contrary to common beliefs in the blockchain community.
    With this result in mind, we develop a framework to design new and evaluate existing
    CCC protocols, focusing on the inherent trust assumptions thereof, and derive
    a classification covering the field of cross-chain communication to date. We conclude
    by discussing open challenges for CCC research and the implications of interoperability
    on the security and privacy of blockchains.
acknowledgement: 'We would like express our gratitude to Georgia Avarikioti, Daniel
  Perez and Dominik Harz for helpful comments and feedback on earlier versions of
  this manuscript. We also thank Nicholas Stifter, Aljosha Judmayer, Philipp Schindler,
  Edgar Weippl, and Alistair Stewart for insightful discussions during the early stages
  of this research. We also wish to thank the anonymous reviewers for their valuable
  comments that helped improve the presentation of our results. This research was
  funded by Bridge 1 858561 SESC; Bridge 1 864738 PR4DLT (all FFG); the Christian
  Doppler Laboratory for Security and Quality Improvement in the Production System
  Lifecycle (CDL-SQI); the competence center SBA-K1 funded by COMET; Chaincode Labs
  through the project SLN: Scalability for the Lightning Network; and by the Austrian
  Science Fund (FWF) through the Meitner program (project M-2608). Mustafa Al-Bassam
  is funded by a scholarship from the Alan Turing Institute. Alexei Zamyatin conducted
  the early stages of this work during his time at SBA Research, and was supported
  by a Binance Research Fellowship.'
alternative_title:
- LNCS
article_processing_charge: No
author:
- first_name: Alexei
  full_name: Zamyatin, Alexei
  last_name: Zamyatin
- first_name: Mustafa
  full_name: Al-Bassam, Mustafa
  last_name: Al-Bassam
- first_name: Dionysis
  full_name: Zindros, Dionysis
  last_name: Zindros
- first_name: Eleftherios
  full_name: Kokoris Kogias, Eleftherios
  id: f5983044-d7ef-11ea-ac6d-fd1430a26d30
  last_name: Kokoris Kogias
- first_name: Pedro
  full_name: Moreno-Sanchez, Pedro
  last_name: Moreno-Sanchez
- first_name: Aggelos
  full_name: Kiayias, Aggelos
  last_name: Kiayias
- first_name: William J.
  full_name: Knottenbelt, William J.
  last_name: Knottenbelt
citation:
  ama: 'Zamyatin A, Al-Bassam M, Zindros D, et al. SoK: Communication across distributed
    ledgers. In: <i>25th International Conference on Financial Cryptography and Data
    Security</i>. Vol 12675. Springer Nature; 2021:3-36. doi:<a href="https://doi.org/10.1007/978-3-662-64331-0_1">10.1007/978-3-662-64331-0_1</a>'
  apa: 'Zamyatin, A., Al-Bassam, M., Zindros, D., Kokoris Kogias, E., Moreno-Sanchez,
    P., Kiayias, A., &#38; Knottenbelt, W. J. (2021). SoK: Communication across distributed
    ledgers. In <i>25th International Conference on Financial Cryptography and Data
    Security</i> (Vol. 12675, pp. 3–36). Virtual: Springer Nature. <a href="https://doi.org/10.1007/978-3-662-64331-0_1">https://doi.org/10.1007/978-3-662-64331-0_1</a>'
  chicago: 'Zamyatin, Alexei, Mustafa Al-Bassam, Dionysis Zindros, Eleftherios Kokoris
    Kogias, Pedro Moreno-Sanchez, Aggelos Kiayias, and William J. Knottenbelt. “SoK:
    Communication across Distributed Ledgers.” In <i>25th International Conference
    on Financial Cryptography and Data Security</i>, 12675:3–36. Springer Nature,
    2021. <a href="https://doi.org/10.1007/978-3-662-64331-0_1">https://doi.org/10.1007/978-3-662-64331-0_1</a>.'
  ieee: 'A. Zamyatin <i>et al.</i>, “SoK: Communication across distributed ledgers,”
    in <i>25th International Conference on Financial Cryptography and Data Security</i>,
    Virtual, 2021, vol. 12675, pp. 3–36.'
  ista: 'Zamyatin A, Al-Bassam M, Zindros D, Kokoris Kogias E, Moreno-Sanchez P, Kiayias
    A, Knottenbelt WJ. 2021. SoK: Communication across distributed ledgers. 25th International
    Conference on Financial Cryptography and Data Security. FC: Financial Cryptography,
    LNCS, vol. 12675, 3–36.'
  mla: 'Zamyatin, Alexei, et al. “SoK: Communication across Distributed Ledgers.”
    <i>25th International Conference on Financial Cryptography and Data Security</i>,
    vol. 12675, Springer Nature, 2021, pp. 3–36, doi:<a href="https://doi.org/10.1007/978-3-662-64331-0_1">10.1007/978-3-662-64331-0_1</a>.'
  short: A. Zamyatin, M. Al-Bassam, D. Zindros, E. Kokoris Kogias, P. Moreno-Sanchez,
    A. Kiayias, W.J. Knottenbelt, in:, 25th International Conference on Financial
    Cryptography and Data Security, Springer Nature, 2021, pp. 3–36.
conference:
  end_date: 2021-03-05
  location: Virtual
  name: 'FC: Financial Cryptography'
  start_date: 2021-03-01
date_created: 2021-11-21T23:01:29Z
date_published: 2021-10-23T00:00:00Z
date_updated: 2023-08-14T12:59:26Z
day: '23'
department:
- _id: ElKo
doi: 10.1007/978-3-662-64331-0_1
external_id:
  isi:
  - '000712016200001'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://eprint.iacr.org/2019/1128
month: '10'
oa: 1
oa_version: Preprint
page: 3-36
publication: 25th International Conference on Financial Cryptography and Data Security
publication_identifier:
  eisbn:
  - 978-3-662-64331-0
  eissn:
  - 1611-3349
  isbn:
  - 9-783-6626-4330-3
  issn:
  - 0302-9743
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'SoK: Communication across distributed ledgers'
type: conference
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: '12675 '
year: '2021'
...