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Key Exchange in the Post-Snowden Era: Universally Composable Subversion-Resilient PAKE

Authors:
Suvradip Chakraborty , VISA Research
Lorenzo Magliocco , Sapienza University of Rome
Bernardo Magri , The University of Manchester
Daniele Venturi , Sapienza University of Rome
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Presentation: Slides
Conference: ASIACRYPT 2024
Abstract: Password-Authenticated Key Exchange (PAKE) allows two parties to establish a common high-entropy secret from a possibly low-entropy pre-shared secret such as a password. In this work, we provide the first PAKE protocol with subversion resilience in the framework of universal composability (UC), where the latter roughly means that UC security still holds even if one of the two parties is malicious and the honest party's code has been subverted (in an undetectable manner). We achieve this result by sanitizing the PAKE protocol from oblivious transfer (OT) due to Canetti et al. (PKC'12) via cryptographic reverse firewalls in the UC framework (Chakraborty et al., EUROCRYPT'22). This requires new techniques, which help us uncover new cryptographic primitives with sanitation-friendly properties along the way (such as OT, dual-mode cryptosystems, and signature schemes). As an additional contribution, we delve deeper in the backbone of communication required in the subversion-resilient UC framework, extending it to the {\em unauthenticated} setting, in line with the work of Barak et al. (CRYPTO'05).
BibTeX
@inproceedings{asiacrypt-2024-34591,
  title={Key Exchange in the Post-Snowden Era: Universally Composable Subversion-Resilient PAKE},
  publisher={Springer-Verlag},
  author={Suvradip Chakraborty and Lorenzo Magliocco and Bernardo Magri and Daniele Venturi},
  year=2024
}