FSLH: Flexible Mechanized Speculative Load Hardening

Fuente: arXiv
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Hauptverfasser: Baumann, Jonathan, Blanco, Roberto, Ducruet, Léon, Harwig, Sebastian, Hritcu, Catalin
Format: Preprint
Veröffentlicht: 2025
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author Baumann, Jonathan
Blanco, Roberto
Ducruet, Léon
Harwig, Sebastian
Hritcu, Catalin
author_facet Baumann, Jonathan
Blanco, Roberto
Ducruet, Léon
Harwig, Sebastian
Hritcu, Catalin
contents The Spectre speculative side-channel attacks pose formidable threats for security. Research has shown that code following the cryptographic constant-time discipline can be efficiently protected against Spectre v1 using a selective variant of Speculative Load Hardening (SLH). SLH was, however, not strong enough for protecting non-cryptographic code, leading to the introduction of Ultimate SLH, which provides protection for arbitrary programs, but has too large overhead for general use, since it conservatively assumes that all data is secret. In this paper we introduce a flexible SLH notion that achieves the best of both worlds by generalizing both Selective and Ultimate SLH. We give a suitable security definition for such transformations protecting arbitrary programs: any transformed program running with speculation should not leak more than what the source program leaks sequentially. We formally prove using the Rocq prover that two flexible SLH variants enforce this relative security guarantee. As easy corollaries we also obtain that, in our setting, Ultimate SLH enforces our relative security notion, and two selective SLH variants enforce speculative constant-time security.
format Preprint
id arxiv_https___arxiv_org_abs_2502_03203
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FSLH: Flexible Mechanized Speculative Load Hardening
Baumann, Jonathan
Blanco, Roberto
Ducruet, Léon
Harwig, Sebastian
Hritcu, Catalin
Cryptography and Security
Programming Languages
The Spectre speculative side-channel attacks pose formidable threats for security. Research has shown that code following the cryptographic constant-time discipline can be efficiently protected against Spectre v1 using a selective variant of Speculative Load Hardening (SLH). SLH was, however, not strong enough for protecting non-cryptographic code, leading to the introduction of Ultimate SLH, which provides protection for arbitrary programs, but has too large overhead for general use, since it conservatively assumes that all data is secret. In this paper we introduce a flexible SLH notion that achieves the best of both worlds by generalizing both Selective and Ultimate SLH. We give a suitable security definition for such transformations protecting arbitrary programs: any transformed program running with speculation should not leak more than what the source program leaks sequentially. We formally prove using the Rocq prover that two flexible SLH variants enforce this relative security guarantee. As easy corollaries we also obtain that, in our setting, Ultimate SLH enforces our relative security notion, and two selective SLH variants enforce speculative constant-time security.
title FSLH: Flexible Mechanized Speculative Load Hardening
topic Cryptography and Security
Programming Languages
url https://arxiv.org/abs/2502.03203