Security Analysis of CPace - Inria - Institut national de recherche en sciences et technologies du numérique Access content directly
Reports (Research Report) Year : 2021

Security Analysis of CPace


In response to standardization requests regarding password-authenticated key exchange (PAKE) protocols, the IRTF working group CFRG has setup a PAKE selection process in 2019, which led to the selection of the CPace protocol in the balanced setting, in which parties share a common password. In subsequent standardization efforts, the CPace protocol further developed, yielding a protocol family whose actual security guarantees in practical settings are not well understood. In this paper, we provide a comprehensive security analysis of CPace in the universal composability framework. Our analysis is realistic in the sense that it captures adaptive corruptions and refrains from modeling CPace's Map2Pt function that maps field elements to curve points as an idealized function. In order to extend our proofs to different CPace variants optimized for specific elliptic-curve ecosystems, we employ a new approach which represents the assumptions required by the proof as libraries accessed by a simulator. By allowing for the modular replacement of assumptions used in the proof, this new approach avoids a repeated analysis of unchanged protocol parts and lets us efficiently analyze the security guarantees of all the different CPace variants. As a result of our analysis, all of the investigated practical CPace variants enjoy adaptive UC security.
Fichier principal
Vignette du fichier
2021-114.pdf (968.2 Ko) Télécharger le fichier
Origin Files produced by the author(s)

Dates and versions

hal-03442101 , version 1 (22-11-2021)


  • HAL Id : hal-03442101 , version 1


Michel Abdalla, Björn Haase, Julia Hesse. Security Analysis of CPace. [Research Report] Report 2021/114, IACR Cryptology ePrint Archive. 2021. ⟨hal-03442101⟩
65 View
126 Download


Gmail Mastodon Facebook X LinkedIn More