TY - GEN
T1 - Reparo: Publicly Verifiable Layer to Repair Blockchains
AU - Thyagarajan, Sri Aravinda Krishnan
AU - Bhat, Adithya
AU - Magri, Bernardo
AU - Tschudi, Daniel
AU - Kate, Aniket
N1 - Funding Information:
We would like to thank Andrew Miller for his valuable comments and constructive feedback. We would also like to thank all the anonymous reviewers for their insightful comments and suggestions to improve the draft. The first author was supported by the German research foundation (DFG) through the collaborative research center 1223, and by the state of Bavaria at the Nuremberg Campus of Technology (NCT). NCT is a research cooperation between the Friedrich-Alexander-Universit?t Erlangen-N?rnberg (FAU) and the Technische Hochschule N?rnberg Georg Simon Ohm (THN). This work also has been partially supported by the National Science Foundation under grant CNS-1846316.
Funding Information:
The first author was supported by the German research foundation (DFG) through the collaborative research center 1223, and by the state of Bavaria at the Nuremberg Campus of Technology (NCT). NCT is a research cooperation between the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and the Technische Hochschule Nürnberg Georg Simon Ohm (THN). This work also has been partially supported by the National Science Foundation under grant CNS-1846316.
Publisher Copyright:
© 2021, International Financial Cryptography Association.
PY - 2021/10/23
Y1 - 2021/10/23
N2 - Although blockchains aim for immutability as their core feature, several instances have exposed the harms with perfect immutability. The permanence of illicit content inserted in Bitcoin poses a challenge to law enforcement agencies like Interpol, and millions of dollars were lost in buggy smart contracts in Ethereum. A line of research then spawned on redactable blockchains with the aim of solving the problem of redacting illicit contents from both permissioned and permissionless blockchains. However, all the existing proposals follow the build-new-chain approach for redactions, and cannot be integrated with existing running blockchains, such as Bitcoin and Ethereum. This work demonstrates that the traditional build-new-chain approach for blockchain redactions is not necessary. We present Reparo (In the Harry Potter universe, ‘ Reparo ’ is a spell that repairs objects), a publicly verifiable layer on top of any blockchain to perform repairs, ranging from fixing buggy contracts to removing illicit contents from the chain. We present an efficient instantiation of Reparo over Ethereum (with proof of work based consensus) for repairing smart contract bugs. In this protocol, any Ethereum user may propose a repair and a deliberation process ensues resulting in a decision that complies with the repair policy of the chain and is publicly verifiable. A repair operation (for instance, fixing a bug in a contract) is then performed according to the repair proposal and the state of Ethereum is updated accordingly. Reparo ’s advantages are multi-fold: (i) Since Reparo follows a layer design, it helps facilitate additional functionalities for Ethereum while maintaining the same provable security guarantees; (ii) Reparo can be easily tailored to different consensus requirements (like proof of stake), does not require heavy cryptographic machinery, and thus, can be integrated with other existing blockchains (such as Bitcoin, Cardano) as well. We evaluate Reparo with Ethereum mainnet and show that the cost of fixing several prominent smart contract bugs is almost negligible. For instance, the cost of repairing the prominent Parity Multisig wallet bug with Reparo is as low as 0.00005 % of the Ethers that can be retrieved after the fix.
AB - Although blockchains aim for immutability as their core feature, several instances have exposed the harms with perfect immutability. The permanence of illicit content inserted in Bitcoin poses a challenge to law enforcement agencies like Interpol, and millions of dollars were lost in buggy smart contracts in Ethereum. A line of research then spawned on redactable blockchains with the aim of solving the problem of redacting illicit contents from both permissioned and permissionless blockchains. However, all the existing proposals follow the build-new-chain approach for redactions, and cannot be integrated with existing running blockchains, such as Bitcoin and Ethereum. This work demonstrates that the traditional build-new-chain approach for blockchain redactions is not necessary. We present Reparo (In the Harry Potter universe, ‘ Reparo ’ is a spell that repairs objects), a publicly verifiable layer on top of any blockchain to perform repairs, ranging from fixing buggy contracts to removing illicit contents from the chain. We present an efficient instantiation of Reparo over Ethereum (with proof of work based consensus) for repairing smart contract bugs. In this protocol, any Ethereum user may propose a repair and a deliberation process ensues resulting in a decision that complies with the repair policy of the chain and is publicly verifiable. A repair operation (for instance, fixing a bug in a contract) is then performed according to the repair proposal and the state of Ethereum is updated accordingly. Reparo ’s advantages are multi-fold: (i) Since Reparo follows a layer design, it helps facilitate additional functionalities for Ethereum while maintaining the same provable security guarantees; (ii) Reparo can be easily tailored to different consensus requirements (like proof of stake), does not require heavy cryptographic machinery, and thus, can be integrated with other existing blockchains (such as Bitcoin, Cardano) as well. We evaluate Reparo with Ethereum mainnet and show that the cost of fixing several prominent smart contract bugs is almost negligible. For instance, the cost of repairing the prominent Parity Multisig wallet bug with Reparo is as low as 0.00005 % of the Ethers that can be retrieved after the fix.
U2 - 10.1007/978-3-662-64331-02
DO - 10.1007/978-3-662-64331-02
M3 - Conference contribution
SN - 9783662643303
VL - 12675
T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
SP - 37
EP - 56
BT - Financial Cryptography and Data Security - 25th International Conference, FC 2021, Virtual Event, March 1-5, 2021, Revised Selected Papers, Part II
A2 - Borisov, Nikita
A2 - Diaz, Claudia
PB - Springer Berlin
ER -