Many prominent smart contract applications such as payment channels, auctions, and voting systems often involve a mechanism in which some party must respond to a challenge or appeal some action within a fixed time limit. This pattern of challenge-response mechanisms poses great risks if, during periods of high transaction volume, the network becomes congested. In this case, fee market competition can prevent the inclusion of the response in blocks, causing great harm. As a result, responders are allowed long periods to submit their response and overpay in fees. To overcome these problems and improve challenge-response protocols, we suggest a secure mechanism that detects congestion in blocks and adjusts the deadline of the response accordingly. The responder is thus guaranteed a deadline extension should congestion arise. We lay theoretical foundations for congestion signals in blockchains and then proceed to analyze and discuss possible attacks on the mechanism and evaluate its robustness. Our results show that in Ethereum, using short response deadlines as low as 3 h, the protocol has >99% defense rate from attacks even by miners with up to 33 % of the computational power. Using shorter deadlines such as one hour is also possible with a similar defense rate for attackers with up to 27 % of the power.
|Original language||American English|
|Title of host publication||Financial Cryptography and Data Security - 26th International Conference, FC 2022, Revised Selected Papers|
|Editors||Ittay Eyal, Juan Garay|
|Publisher||Springer Science and Business Media Deutschland GmbH|
|Number of pages||19|
|State||Published - 2022|
|Event||26th International Conference on Financial Cryptography and Data Security, FC 2022 - Saint George, Grenada|
Duration: 2 May 2022 → 6 May 2022
|Name||Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)|
|Conference||26th International Conference on Financial Cryptography and Data Security, FC 2022|
|Period||2/05/22 → 6/05/22|
Bibliographical noteFunding Information:
Acknowledgments. Ayelet Lotem and Aviv Zohar are partially supported by grants from the Israel Science Foundation (grants 1504/17 & 1443/21) and by a grant from the HUJI Cyber Security Research Center in conjunction with the Israel National Cyber Bureau.
© 2022, International Financial Cryptography Association.