Conference item
Lossy CSI-FiSh: Efficient signature scheme with tight reduction to decisional CSIDH-512
- Abstract:
- Recently, Beullens, Kleinjung, and Vercauteren (Asiacrypt'19) provided the first practical isogeny-based digital signature, obtained from the Fiat-Shamir (FS) paradigm. They worked with the CSIDH-512 parameters and passed through a new record class group computation. However, as with all standard FS signatures, the security proof is highly non-tight and the concrete parameters are set under the heuristic that the only way to attack the scheme is by finding collisions for a hash function. In this paper, we propose an FS-style signature scheme, called Lossy CSI-FiSh, constructed using the CSIDH-512 parameters and with a security proof based on the "Lossy Keys" technique introduced by Kiltz, Lyubashevsky and Schaffner (Eurocrypt'18). Lossy CSI-FiSh is provably secure under the same assumption which underlies the security of the key exchange protocol CSIDH (Castryck et al. (Asiacrypt'18)) and is almost as efficient as CSI-FiSh. For instance, aiming for small signature size, our scheme is expected to take around ≈800ms to sign/verify while producing signatures of size ≈280 bytes. This is only twice slower than CSI-FiSh while having similar signature size for the same parameter set. As an additional benefit, our scheme is by construction secure both in the classical and quantum random oracle model.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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Access Document
- Files:
-
-
(Preview, Accepted manuscript, 460.8KB, Terms of use)
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- Publisher copy:
- 10.1007/978-3-030-45388-6_6
Authors
- Publisher:
- Springer Verlag
- Series:
- Lecture Notes in Computer Science
- Series number:
- 12111
- Publication date:
- 2020-04-29
- Acceptance date:
- 2020-01-19
- Event title:
- IACR International Conference on Practice and Theory of Public-Key Cryptography (PKC) 2020
- Event location:
- Edinburgh, Scotland
- Event website:
- https://pkc.iacr.org/2020/index.html
- Event start date:
- 2020-05-04
- Event end date:
- 2020-05-07
- DOI:
- ISSN:
-
0302-9743
- EISBN:
- 9783030453886
- ISBN:
- 9783030453879
- Language:
-
English
- Keywords:
- Pubs id:
-
1085729
- Local pid:
-
pubs:1085729
- Deposit date:
-
2020-02-07
Terms of use
- Copyright holder:
- International Association for Cryptologic Research
- Copyright date:
- 2020
- Rights statement:
- © International Association for Cryptologic Research 2020
- Notes:
- This paper has been accepted for presentation at the International Conference on Practice and Theory in Public-Key Cryptography (PKC), 04-07 May 2020, Edinburgh, Scotland. This is the accepted manuscript version of the article. The final version is available online from Springer at: https://doi.org/10.1007/978-3-030-45388-6_6
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