(Short Paper) Analysis of a Strong Fault Attack on Static/Ephemeral CSIDH

LeGrow, Jason T.; Hutchinson, Aaron

doi:10.1007/978-3-030-85987-9_12

Cited by 4 publications

(2 citation statements)

References 12 publications

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“…One can modify memory locations and observe if this changes the resulting shared secret [11]. A different attack avenue is to target fault injections against dummy computations in CSIDH [10,28]. We emphasize that these are attacks against specific implementations and variants of CSIDH.…”

Section: Related Workmentioning

confidence: 99%

“…Although these attacks are implementation-specific, the proposed countermeasures impact our attack too. Typically, real isogenies are computed prior to dummy isogenies, but the order of real and dummy isogenies can be randomized [10,28] with essentially no computational overhead. When applied to dummy-based implementations, e.g., from [30,32], this randomization means dummy isogenies can appear in different rounds for each run, which makes the definitions of the curves E r,± almost obsolete.…”

Section: Previous Fault Attacks and Countermeasuresmentioning

confidence: 99%

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Disorientation Faults in CSIDH

Banegas

Krämer

Lange

et al. 2023

Lecture Notes in Computer Science

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We investigate a new class of fault-injection attacks against the CSIDH family of cryptographic group actions. Our disorientation attacks effectively flip the direction of some isogeny steps. We achieve this by faulting a specific subroutine, connected to the Legendre symbol or Elligator computations performed during the evaluation of the group action. These subroutines are present in almost all known CSIDH implementations. Post-processing a set of faulty samples allows us to infer constraints on the secret key. The details are implementation specific, but we show that in many cases, it is possible to recover the full secret key with only a modest number of successful fault injections and modest computational resources. We provide full details for attacking the original CSIDH proof-of-concept software as well as the CTIDH constant-time * Author list in alphabetical order; see https://ams.org/profession/leaders/ CultureStatement04.pdf.

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Section: Related Workmentioning

confidence: 99%