×

zbMATH — the first resource for mathematics

Adding concurrency to smart contracts. (English) Zbl 1445.68083
Summary: Modern cryptocurrency systems, such as the Ethereum project, permit complex financial transactions through scripts called smart contracts. These smart contracts are executed many, many times, always without real concurrency. First, all smart contracts are serially executed by miners before appending them to the blockchain. Later, those contracts are serially re-executed by validators to verify that the smart contracts were executed correctly by miners. Serial execution limits system throughput and fails to exploit today’s concurrent multicore and cluster architectures. Nevertheless, serial execution appears to be required: contracts share state, and contract programming languages have a serial semantics. This paper presents a novel way to permit miners and validators to execute smart contracts in parallel, based on techniques adapted from software transactional memory. Miners execute smart contracts speculatively in parallel, allowing non-conflicting contracts to proceed concurrently, and “discovering” a serializable concurrent schedule for a block’s transactions, This schedule is captured and encoded as a deterministic fork-join program used by validators to re-execute the miner’s parallel schedule deterministically but concurrently. We have proved that the validator’s execution is equivalent to miner’s execution. Smart contract benchmarks run on a JVM with ScalaSTM show that a speedup of \(1.39 \times\) can be obtained for miners and \(1.59 \times\) for validators with just three concurrent threads.

MSC:
68P25 Data encryption (aspects in computer science)
68Q85 Models and methods for concurrent and distributed computing (process algebras, bisimulation, transition nets, etc.)
94A60 Cryptography
Software:
Cilk; GitHub; ScalaSTM
PDF BibTeX XML Cite
Full Text: DOI
References:
[1] Androulaki, E., Barger, A., Bortnikov, V., Cachin, C., Christidis, K., De Caro, A., Enyeart, D., Ferris, C., Laventman, G., Manevich, Y., et al.: Hyperledger fabric: a distributed operating system for permissioned blockchains. In: Proceedings of the Thirteenth EuroSys Conference, ACM, p. 30 (2018)
[2] Blumofe, R.D., Joerg, C.F., Kuszmaul, B.C., Leiserson, C.E., Randall, K.H., Zhou, Y.: Cilk: an efficient multithreaded runtime system. In: Proceedings of the Fifth ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming, PPOPP ’95, ACM, New York, NY, USA, pp. 207-216 (1995). doi:10.1145/209936.209958
[3] Bocchino Jr., R.L., Adve, V.S., Adve, S.V., Snir, M.: Parallel programming must be deterministic by default. In: Proceedings of the First USENIX Conference on Hot Topics in Parallelism, HotPar’09, USENIX Association, Berkeley, CA, USA, pp. 4-4 (2009). URL http://dl.acm.org/citation.cfm?id=1855591.1855595
[4] Bronson, N.G., Casper, J., Chafi, H., Olukotun, K.: Transactional predication: high-performance concurrent sets and maps for stm. In: Proceedings of the 29th ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing, PODC ’10, ACM, New York, NY, USA, pp. 6-15 (2010). doi:10.1145/1835698.1835703
[5] Cachin, C., Schubert, S., Vukolic, M.: Non-determinism in byzantine fault-tolerant replication. In: Fatourou, P., Jiménez, F., Pedone, F. (eds.) 20th International Conference on Principles of Distributed Systems (OPODIS 2016), Leibniz International Proceedings in Informatics (LIPIcs), vol. 70, Schloss Dagstuhl-Leibniz-Zentrum fuer Informatik, Dagstuhl, Germany, pp. 24:1-24:16 (2017). doi:10.4230/LIPIcs.OPODIS.2016.24. http://drops.dagstuhl.de/opus/volltexte/2017/7093 · Zbl 1432.68021
[6] Castro, M., Liskov, B.: Practical byzantine fault tolerance. In: Proceedings of the Third Symposium on Operating Systems Design and Implementation, OSDI ’99, USENIX Association, Berkeley, CA, USA, pp. 173-186 (1999). URL http://dl.acm.org/citation.cfm?id=296806.296824
[7] DAO: Thedao smart contract. Retrieved 8 February (2017)
[8] Delmolino, K., Arnett, M., Kosba, A., Miller, A., Shi, E.: Step by Step Towards Creating a Safe Smart Contract: Lessons and Insights from a Cryptocurrency Lab, Springer, Berlin, pp. 79-94 (2016). doi:10.1007/978-3-662-53357-4_6
[9] Ethereum: https://github.com/ethereum/
[10] Ethereum design Rationale: http://github.com/ethereum/wiki/wiki/Design-Rationale#gas-and-fees
[11] Herlihy, M., Koskinen, E.: Transactional boosting: a methodology for highly-concurrent transactional objects. In: Proceedings of the 13th ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming, PPoPP ’08, ACM, New York, NY, USA, pp. 207-216 (2008). doi:10.1145/1345206.1345237
[12] Herlihy, M., Luchangco, V., Moir, M., Scherer III, W.N.: Software transactional memory for dynamic-sized data structures. In: Proceedings of the Twenty-second Annual Symposium on Principles of Distributed Computing, PODC ’03, ACM, New York, NY, USA, pp. 92-101 (2003). doi:10.1145/872035.872048
[13] Herman, N., Inala, J.P., Huang, Y., Tsai, L., Kohler, E., Liskov, B., Shrira, L.: Type-aware transactions for faster concurrent code. In: Proceedings of the Eleventh European Conference on Computer Systems, EuroSys ’16, ACM, New York, NY, USA, pp. 31:1-31:16 (2016). doi:10.1145/2901318.2901348
[14] Hyperledger white paper. http://www.the-blockchain.com/docs/Hyperledger
[15] Kosba, A.E., Miller, A., Shi, E., Wen, Z., Papamanthou, C.: Hawk: the blockchain model of cryptography and privacy-preserving smart contracts. In: IEEE Symposium on Security and Privacy (2015)
[16] Koskinen, E., Parkinson, M.J.: The push/pull model of transactions. In: Proceedings of the 36th ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI’15), Portland, OR, USA. ACM (2015)
[17] Luu, L., Chu, D., Olickel, H., Saxena, P., Hobor, A.: Making smart contracts smarter. In: Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security, Vienna, Austria, October 24-28, pp. 254-269 (2016)
[18] Luu, L., Teutsch, J., Kulkarni, R., Saxena, P.: Demystifying incentives in the consensus computer. In: Proceedings of the 22Nd ACM SIGSAC Conference on Computer and Communications Security, CCS ’15, ACM, New York, NY, USA, pp. 706-719 (2015). doi:10.1145/2810103.2813659
[19] Nakamoto, S.: Bitcoin: A peer-to-peer electronic cash system (2009). URL http://www.bitcoin.org/bitcoin.pdf
[20] Scala STM Expert Group.: Scalastm. web. Retrieved from http://nbronson.github.com/scala-stm/, 20 November (2011)
[21] Solidity documentation: http://solidity.readthedocs.io/en/latest/index.html
[22] Solidity documentation: Solidity by example: http://solidity.readthedocs.io/en/develop/solidity-by-example.html
[23] Szabo, N.: Formalizing and securing relationships on public networks. First Monday 2(9) (1997). http://firstmonday.org/ojs/index.php/fm/article/view/548
[24] Wood, G.: Ethereum: a secure decentralised generalised transaction ledger. http://gavwood.com/Paper.pdf
[25] Why do smart contract languages need to be deterministic? https://ethereum.stackexchange.com/questions/3557/why-do-smart-contract-languages-need-to-be-deterministic
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. It attempts to reflect the references listed in the original paper as accurately as possible without claiming the completeness or perfect precision of the matching.