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(Short Paper) PieceWork: Generalized Outsourcing Control for Proofs of Work

  • Philip DaianEmail author
  • Ittay Eyal
  • Ari Juels
  • Emin Gün Sirer
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10323)

Abstract

Most prominent cryptocurrencies utilize proof of work (PoW) to secure their operation, yet PoW suffers from two key undesirable properties. First, the work done is generally wasted, not useful for anything but the gleaned security of the cryptocurrency. Second, PoW is naturally outsourceable, leading to inegalitarian concentration of power in the hands of few so-called pools that command large portions of the system’s computation power.

We introduce a general approach to constructing PoW called PieceWork that tackles both issues. In essence, PieceWork allows for a configurable fraction of PoW computation to be outsourced to workers. Its controlled outsourcing allows for reusing the work towards additional goals such as spam prevention and DoS mitigation, thereby reducing PoW waste. Meanwhile, PieceWork can be tuned to prevent excessive outsourcing. Doing so causes pool operation to be significantly more costly than today. This disincentivizes aggregation of work in mining pools.

Notes

Acknowledgments

This work is funded in part by NSF grants CNS-1330599, CNS-1514163, CNS-1564102, CNS-1561209, and CNS-1518779, ARO grant W911NF-16-1-0145, and IC3 sponsorship from Chain, IBM, and Intel.

References

  1. 1.
    Back, A.: Hashcash - a denial of service counter-measure. http://www.hashcash.org/papers/hashcash.pdf (2002)
  2. 2.
    Back, A.: Hashcash-amortizable publicly auditable cost functions. Early draft of paper (2000)Google Scholar
  3. 3.
    Biryukov, A., Pustogarov, I.: Proof-of-work as anonymous micropayment: rewarding a Tor relay. In: Böhme, R., Okamoto, T. (eds.) FC 2015. LNCS, vol. 8975, pp. 445–455. Springer, Heidelberg (2015).  https://doi.org/10.1007/978-3-662-47854-7_27 CrossRefGoogle Scholar
  4. 4.
    Courtois, N.T., Bahack, L.: On subversive miner strategies and block withholding attack in Bitcoin digital currency. arXiv preprint arXiv:1402.1718 (2014)
  5. 5.
    Dwork, C., Naor, M.: Pricing via processing or combatting junk mail. In: Brickell, E.F. (ed.) CRYPTO 1992. LNCS, vol. 740, pp. 139–147. Springer, Heidelberg (1993).  https://doi.org/10.1007/3-540-48071-4_10 Google Scholar
  6. 6.
    Ethereum Proof of Stake FAQ (2017). https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ. Accessed 28 Feb 2017
  7. 7.
    Eyal, I.: The miner’s dilemma. In: 2015 IEEE Symposium on Security and Privacy, pp. 89–103. IEEE (2015)Google Scholar
  8. 8.
    Eyal, I., Sirer, E.G.: How to disincentivize large bitcoin mining pools. http://hackingdistributed.com/2014/06/18/how-to-disincentivize-large-bitcoin-mining-pools/ (2014). Accessed 05 Nov 2016
  9. 9.
    Jakobsson, M., Juels, A.: Proofs of work and bread pudding protocols (extended abstract). In: Preneel, B. (ed.) Secure Information Networks. ITIFIP, vol. 23, pp. 258–272. Springer, Boston, MA (1999).  https://doi.org/10.1007/978-0-387-35568-9_18 CrossRefGoogle Scholar
  10. 10.
    Juels, A., Brainard, J.: Client puzzles: a cryptographic countermeasure against connection depletion attacks. In: NDSS, pp. 151–165 (1999)Google Scholar
  11. 11.
    Juels Jr., A., Burton, S.K.: PORs: proofs of retrievability for large files. In: ACM CCS, pp. 584–597 (2007)Google Scholar
  12. 12.
    King, S.: Primecoin: cryptocurrency with prime number proof-of-work (2013)Google Scholar
  13. 13.
    Micali, S., Rivest, R.L.: Micropayments revisited. In: Preneel, B. (ed.) CT-RSA 2002. LNCS, vol. 2271, pp. 149–163. Springer, Heidelberg (2002).  https://doi.org/10.1007/3-540-45760-7_11 CrossRefGoogle Scholar
  14. 14.
    Miller, A., Juels, A., Shi, E., Parno, B., Katz, J.: Permacoin: repurposing bitcoin work for data preservation. In: 2014 IEEE Symposium on Security and Privacy, pp. 475–490. IEEE (2014)Google Scholar
  15. 15.
    Miller, A., Kosba, A., Katz, J., Shi, E.: Nonoutsourceable scratch-off puzzles to discourage bitcoin mining coalitions. In: Proceedings of the 22nd ACM SIGSAC Conference on Computer and Communications Security, pp. 680–691. ACM (2015)Google Scholar
  16. 16.
    Nakamoto, S.: Bitcoin: a peer-to-peer electronic cash system. (2008). http://bitcoin.org/bitcoin.pdf
  17. 17.
    Nguyen, P., Stern, J.: The Béguin-Quisquater server-aided RSA protocol from Crypto’95 is not secure. In: Ohta, K., Pei, D. (eds.) ASIACRYPT 1998. LNCS, vol. 1514, pp. 372–379. Springer, Heidelberg (1998).  https://doi.org/10.1007/3-540-49649-1_29 CrossRefGoogle Scholar
  18. 18.
    Nygren, E., Erb, S., Biryukov, A., Khovratovic, D.: TLS client puzzles extension. IETF Internet-Draft (2016). Expires 30 Dec 2016Google Scholar
  19. 19.
    Priest, C.: [bitcoin-dev] we need to fix the block withholding attack. https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-December/012059.html (2015). Accessed 05 Nov 2016
  20. 20.
    Rivest, R.L., Shamir, A.: PayWord and MicroMint: two simple micropayment schemes. In: Lomas, M. (ed.) Security Protocols 1996. LNCS, vol. 1189, pp. 69–87. Springer, Heidelberg (1997).  https://doi.org/10.1007/3-540-62494-5_6 CrossRefGoogle Scholar
  21. 21.
    Sztorc, P.: Nothing is cheaper than proof of work (2016). http://www.truthcoin.info/blog/pow-cheapest/. Accessed 01 Nov 2016
  22. 22.
    Todd, P.: Re: [bitcoin-dev] we need to fix the block withholding attack (2015). https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-December/012069.html. Accessed 05 Nov 2016
  23. 23.
    ziftrCOIN: a cryptocurrency to enable commerces. (2014). https://d19y4lldx7po3t.cloudfront.net/assets/docs/ziftrcoin-whitepaper-120614.pdf. Accessed 05 Nov 2016

Copyright information

© International Financial Cryptography Association 2017

Authors and Affiliations

  • Philip Daian
    • 1
    Email author
  • Ittay Eyal
    • 1
  • Ari Juels
    • 2
  • Emin Gün Sirer
    • 1
  1. 1.Department of Computer ScienceCornell UniversityIthacaUSA
  2. 2.Jacobs Technion-Cornell InstituteCornell TechNew YorkUSA

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