CryptoDB
Post-Quantum Privacy Pass via Post-Quantum Anonymous Credentials
| Authors: | |
|---|---|
| Download: | |
| Presentation: | Slides |
| Abstract: | It is known that one can generically construct a very flexible post-quantum anonymous credential scheme, supporting the showing of arbitrary predicates on its attributes using general-purpose zero-knowledge proofs secure against quantum adversaries [Fischlin, CRYPTO 2006]. Traditionally, such a generic instantiation is thought to come with impractical sizes and performance but recent advances in succinct proofs warrant a reconsideration. We show that with careful choices and optimizations, such a scheme can perform surprisingly well. In fact, it can even perform competitively against state-of-the-art post-quantum blind signatures, for the simpler problem of post-quantum unlinkable tokens, required for a post-quantum version of \emph{privacy pass}. To wit, a post-quantum privacy pass constructed in this way using zkDilithium, our proposal for a STARK-friendly variation on Dilithium2, allows for a trade-off between token size (76--172 kB) and generation time (0.25--4.5s) with a target proof security level of 115 bits. Verification of these tokens can be done in ~30ms. We argue that these tokens are reasonably practical, adding less than a second upload time over traditional tokens, supported by a measurement study. We also discuss how our construction enables an improved version of rate-limited privacy pass that does not require an attester and hides usage patterns of clients. |
| Video: | https://youtu.be/IAOWRO9Qn10?t=3102 |
BibTeX
@misc{rwc-2023-35439,
title={Post-Quantum Privacy Pass via Post-Quantum Anonymous Credentials},
note={Video at \url{https://youtu.be/IAOWRO9Qn10?t=3102}},
howpublished={Talk given at RWC 2023},
author={Guru-Vamsi Policharla and Bas Westerbaan and Armando Faz-Hernández and Chris Wood},
year=2023
}