Another Look at Extraction and Randomization of Groth's zk-SNARK

Karim Baghery; Markulf Kohlweiss; Janno Siim; Mikhail Volkhov

doi:10.1007%2F978-3-662-64322-8_22

Another Look at Extraction and Randomization of Groth's zk-SNARK

Karim Baghery, Markulf Kohlweiss, Janno Siim, Mikhail Volkhov

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Abstract / Description of output

Due to the simplicity and performance of zk-SNARKs they are widely used in real-world cryptographic protocols, including blockchain and smart contract systems. Simulation Extractability (SE) is a necessary security property for a NIZK argument to achieve Universal Composability (UC), a common requirement for such protocols. Most of the works that investigate SE focus on its strong variant which implies proof non-malleability. In this work we investigate a relaxed weaker notion, that allows proof randomization, while guaranteeing statement non-malleability, which we argue to be a more natural security property. First, we show that it is already achievable by Groth16, arguably the most efficient and widely deployed SNARK nowadays. Second, we show that because of this, Groth16 can be efficiently transformed into a black-box weakly SE NIZK, which is sufficient for UC protocols.

Original language	English
Title of host publication	Financial Cryptography and Data Security
Editors	Nikita Borisov, Claudia Diaz
Place of Publication	Berlin, Heidelberg
Publisher	Springer
Pages	457-475
Number of pages	19
ISBN (Electronic)	978-3-662-64322-8
ISBN (Print)	978-3-662-64321-1
DOIs	https://doi.org/10.1007%2F978-3-662-64322-8_22
Publication status	Published - 23 Oct 2021
Event	Financial Cryptography and Data Security 2021 Twenty-Fifth International Conference - Virtual Conference Duration: 1 Mar 2021 → 5 Mar 2021 Conference number: 25 https://fc21.ifca.ai/index.php

Publication series

Name	Lecture Notes in Computer Science
Publisher	Springer
Volume	12674
ISSN (Print)	0302-9743
ISSN (Electronic)	1611-3349

Conference

Conference	Financial Cryptography and Data Security 2021 Twenty-Fifth International Conference
Period	1/03/21 → 5/03/21
Internet address	https://fc21.ifca.ai/index.php

Keywords / Materials (for Non-textual outputs)

zk-SNARKs
Simulation extractability
UC security

Access to Document

10.1007%2F978-3-662-64322-8_22Licence: All Rights Reserved

Another Look_BAGHERY_DOA03122020_AFVAccepted author manuscript, 609 KBLicence: Creative Commons: Attribution (CC-BY)

https://eprint.iacr.org/2020/811Licence: Creative Commons: Attribution (CC-BY)
https://link.springer.com/chapter/10.1007%2F978-3-662-64322-8_22Licence: All Rights Reserved

PRIViLEDGE: Privacy in Distributed Ledgers
Kiayias, A.
EU government bodies
1/01/18 → 30/06/21
Project: Research

Cite this

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title = "Another Look at Extraction and Randomization of Groth's zk-SNARK",

abstract = "Due to the simplicity and performance of zk-SNARKs they are widely used in real-world cryptographic protocols, including blockchain and smart contract systems. Simulation Extractability (SE) is a necessary security property for a NIZK argument to achieve Universal Composability (UC), a common requirement for such protocols. Most of the works that investigate SE focus on its strong variant which implies proof non-malleability. In this work we investigate a relaxed weaker notion, that allows proof randomization, while guaranteeing statement non-malleability, which we argue to be a more natural security property. First, we show that it is already achievable by Groth16, arguably the most efficient and widely deployed SNARK nowadays. Second, we show that because of this, Groth16 can be efficiently transformed into a black-box weakly SE NIZK, which is sufficient for UC protocols.",

keywords = "zk-SNARKs, Simulation extractability, UC security",

author = "Karim Baghery and Markulf Kohlweiss and Janno Siim and Mikhail Volkhov",

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Baghery, K, Kohlweiss, M, Siim, J & Volkhov, M 2021, Another Look at Extraction and Randomization of Groth's zk-SNARK. in N Borisov & C Diaz (eds), Financial Cryptography and Data Security. Lecture Notes in Computer Science, vol. 12674, Springer, Berlin, Heidelberg, pp. 457-475, Financial Cryptography and Data Security 2021 Twenty-Fifth International Conference, 1/03/21. https://doi.org/10.1007%2F978-3-662-64322-8_22

Another Look at Extraction and Randomization of Groth's zk-SNARK. / Baghery, Karim; Kohlweiss, Markulf; Siim, Janno et al.
Financial Cryptography and Data Security. ed. / Nikita Borisov; Claudia Diaz. Berlin, Heidelberg: Springer, 2021. p. 457-475 (Lecture Notes in Computer Science; Vol. 12674).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

TY - GEN

T1 - Another Look at Extraction and Randomization of Groth's zk-SNARK

AU - Baghery, Karim

AU - Kohlweiss, Markulf

AU - Siim, Janno

AU - Volkhov, Mikhail

N1 - Conference code: 25

PY - 2021/10/23

Y1 - 2021/10/23

N2 - Due to the simplicity and performance of zk-SNARKs they are widely used in real-world cryptographic protocols, including blockchain and smart contract systems. Simulation Extractability (SE) is a necessary security property for a NIZK argument to achieve Universal Composability (UC), a common requirement for such protocols. Most of the works that investigate SE focus on its strong variant which implies proof non-malleability. In this work we investigate a relaxed weaker notion, that allows proof randomization, while guaranteeing statement non-malleability, which we argue to be a more natural security property. First, we show that it is already achievable by Groth16, arguably the most efficient and widely deployed SNARK nowadays. Second, we show that because of this, Groth16 can be efficiently transformed into a black-box weakly SE NIZK, which is sufficient for UC protocols.

AB - Due to the simplicity and performance of zk-SNARKs they are widely used in real-world cryptographic protocols, including blockchain and smart contract systems. Simulation Extractability (SE) is a necessary security property for a NIZK argument to achieve Universal Composability (UC), a common requirement for such protocols. Most of the works that investigate SE focus on its strong variant which implies proof non-malleability. In this work we investigate a relaxed weaker notion, that allows proof randomization, while guaranteeing statement non-malleability, which we argue to be a more natural security property. First, we show that it is already achievable by Groth16, arguably the most efficient and widely deployed SNARK nowadays. Second, we show that because of this, Groth16 can be efficiently transformed into a black-box weakly SE NIZK, which is sufficient for UC protocols.

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BT - Financial Cryptography and Data Security

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