Recognition: unknown
A Deductive System for Contract Satisfaction Proofs
Pith reviewed 2026-05-10 17:09 UTC · model grok-4.3
The pith
A deductive proof system for relative trace equality enables modular interactive proofs that CPUs satisfy hardware-software leakage contracts.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Contract satisfaction is an instance of relative trace equality, and relative bisimulation provides a practical proof principle for it. The authors construct a deductive proof system that is sound and complete for relative trace equality, permits modular and incremental development of proofs, and contains additional reasoning principles that simplify arguments by using symmetries and transitivity. The system has been formalized and successfully applied to two non-trivial contract satisfaction examples.
What carries the argument
The deductive proof system for relative trace equality, built on relative bisimulation and equipped with modular composition rules plus symmetry and transitivity principles.
If this is right
- Proofs can be split into independent sub-proofs that are developed and maintained separately.
- Interactive theorem provers become a viable alternative to model-checking approaches for contract verification.
- Symmetries in leakage behavior can be used directly to shorten proofs rather than being rediscovered each time.
- Completeness guarantees that any valid relative trace equality can eventually be established within the system.
Where Pith is reading between the lines
- The same modular coinductive style could be reused for other infinite-trace properties of hardware abstractions beyond leakage contracts.
- The symmetry and transitivity rules might transfer to verification tasks involving equivalent execution behaviors in compilers or operating systems.
- Because the system is formalized, it opens the possibility of certified proof scripts that can be checked by independent tools.
Load-bearing premise
That contract satisfaction for real CPUs reduces exactly to relative trace equality and that relative bisimulation plus the supplied symmetry and transitivity rules suffice to finish the proofs without extra ad-hoc reasoning.
What would settle it
A concrete contract satisfaction instance that is true under the definition of relative trace equality yet cannot be proved inside the deductive system even after exhaustive use of its modular, symmetry, and transitivity rules.
Figures
read the original abstract
Hardware-software contracts are abstract specifications of a CPU's leakage behavior. They enable verifying the security of high-level programs against side-channel attacks without having to explicitly reason about the microarchitectural details of the CPU. Using the abstraction powers of a contract requires proving that the targeted CPU satisfies the contract in the sense that the contract over-approximates the CPU's leakage. Besides pen-and-paper reasoning, proving contract satisfaction has been approached mostly from the model-checking perspective, with approaches based on a (semi-)automated search for the necessary invariants. As an alternative, this paper explores how such proofs can be conducted in interactive proof assistants. We start by observing that contract satisfaction is an instance of a more general problem we call relative trace equality, and we introduce relative bisimulation as an associated proof technique. Leveraging recent advances in the field of coinductive proofs, we develop a deductive proof system for relative trace equality. Our system is provably sound and complete, and it enables a modular and incremental proof style. It also features several reasoning principles to simplify proofs by exploiting symmetries and transitivity properties. We formalized our deductive system in the Rocq proof assistant and applied it to two challenging contract satisfaction proofs.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper develops a deductive proof system for relative trace equality (an instance of contract satisfaction for CPU leakage), based on relative bisimulation. It claims the system is sound and complete, formalized in Rocq, supports modular/incremental proofs, and includes rules exploiting symmetries and transitivity; the system is applied to two challenging contract satisfaction proofs as an alternative to model-checking approaches.
Significance. If the Rocq formalization is gap-free and the two examples confirm that proofs remain strictly inside the deductive system (using only the listed rules without external invariants or ad-hoc lemmas), the work provides a valuable machine-checked foundation for interactive verification of hardware-software contracts. The emphasis on modularity and the coinductive advances leveraged are strengths that could improve reliability over search-based methods for side-channel security proofs.
major comments (2)
- The central claim that the deductive system enables modular contract-satisfaction proofs for real CPUs depends on the two Rocq examples using only the provided symmetries/transitivity rules and relative bisimulation without additional state invariants or external lemmas. The manuscript must include excerpts or proof outlines from the examples section showing this explicitly, as the abstract provides no such detail and the reduction from contract satisfaction to relative trace equality is assumed without further justification.
- § on formalization and completeness: while soundness and completeness are stated to be machine-checked in Rocq, the paper should reference the specific theorems or files establishing completeness for relative trace equality (beyond the abstract claim), to allow assessment of whether the system is sufficiently complete for the challenging examples without gaps.
Simulated Author's Rebuttal
We thank the referee for the thoughtful and constructive review. The comments highlight important points for improving clarity and verifiability. We address each major comment below and will incorporate revisions to strengthen the manuscript.
read point-by-point responses
-
Referee: The central claim that the deductive system enables modular contract-satisfaction proofs for real CPUs depends on the two Rocq examples using only the provided symmetries/transitivity rules and relative bisimulation without additional state invariants or external lemmas. The manuscript must include excerpts or proof outlines from the examples section showing this explicitly, as the abstract provides no such detail and the reduction from contract satisfaction to relative trace equality is assumed without further justification.
Authors: We agree that explicit demonstration from the examples is essential to substantiate the modularity claim. In the revised manuscript, we will expand the examples section with proof outlines and selected excerpts from the Rocq developments. These will explicitly show that the two contract satisfaction proofs are carried out using only the deductive rules, relative bisimulation, symmetry, and transitivity principles, without external state invariants or ad-hoc lemmas. We will also add a concise justification of the reduction from contract satisfaction to relative trace equality in the introduction or a dedicated preliminaries subsection. revision: yes
-
Referee: § on formalization and completeness: while soundness and completeness are stated to be machine-checked in Rocq, the paper should reference the specific theorems or files establishing completeness for relative trace equality (beyond the abstract claim), to allow assessment of whether the system is sufficiently complete for the challenging examples without gaps.
Authors: We acknowledge the value of precise references for independent assessment. The revised manuscript will include explicit citations to the relevant Rocq theorems (in particular, the machine-checked completeness theorem for relative trace equality) together with the corresponding files and modules in the formalization. This will allow readers to locate the proofs and evaluate their applicability to the examples. revision: yes
Circularity Check
No circularity: deductive system derived from explicit definitions of relative trace equality with independent soundness proof in Rocq.
full rationale
The paper begins by defining relative trace equality as the target relation and relative bisimulation as the associated proof technique. It then constructs a deductive proof system whose rules are justified directly from these definitions, with soundness and completeness established via a separate formalization in the Rocq proof assistant. No step reduces a derived claim back to its own inputs by construction, no parameters are fitted and then relabeled as predictions, and no load-bearing premises rest on self-citations or prior ansatzes from the same authors. The two contract-satisfaction examples are presented as applications of the system rather than as inputs that define it. The development is therefore self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
axioms (1)
- standard math Coinductive principles suffice to establish relative trace equality via bisimulation
invented entities (1)
-
relative bisimulation
no independent evidence
Reference graph
Works this paper leans on
-
[1]
Basavesh Ammanaghatta Shivakumar, Gilles Barthe, Benjamin Grégoire, Vincent Laporte, and Swarn Priya. 2022. Enforcing Fine-grained Constant-time Policies. InProceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security(Los Angeles, CA, USA)(CCS ’22). Association for Computing Machinery, New York, NY, USA, 83–96. doi:10.1145/3548606.3560689
-
[2]
Santiago Arranz Olmos, Gilles Barthe, Lionel Blatter, Benjamin Grégoire, and Vincent Laporte. 2025. Preservation of Speculative Constant-Time by Compilation.Proc. ACM Program. Lang.9, POPL, Article 44 (Jan. 2025), 33 pages. doi:10.1145/3704880
-
[3]
Frans Kaashoek, Joseph Tassarotti, and Nickolai Zeldovich
Anish Athalye, Henry Corrigan-Gibbs, M. Frans Kaashoek, Joseph Tassarotti, and Nickolai Zeldovich. 2024. Modular Verification of Secure and Leakage-Free Systems: From Application Specification to Circuit-Level Implementation. In Proceedings of the ACM SIGOPS 30th Symposium on Operating Systems Principles, SOSP 2024, Austin, TX, USA, November 4-6, 2024. AC...
2024
-
[4]
Frans Kaashoek, and Nickolai Zeldovich
Anish Athalye, M. Frans Kaashoek, and Nickolai Zeldovich. 2022. Verifying Hardware Security Modules with Information-Preserving Refinement. In16th USENIX Symposium on Operating Systems Design and Implementation (OSDI 22). USENIX Association, 503–519
2022
-
[5]
Enrico Barberis, Pietro Frigo, Marius Muench, Herbert Bos, and Cristiano Giuffrida. 2022. Branch History Injection: On the Effectiveness of Hardware Mitigations Against Cross-Privilege Spectre-v2 Attacks. In31st USENIX Security Symposium (USENIX Security 22). USENIX Association, Boston, MA, 971–988. https://www.usenix.org/conference/ usenixsecurity22/pres...
2022
-
[6]
Gilles Barthe, Sandrine Blazy, Benjamin Grégoire, Rémi Hutin, Vincent Laporte, David Pichardie, and Alix Trieu. 2019. Formal verification of a constant-time preserving C compiler.Proc. ACM Program. Lang.4, POPL, Article 7 (Dec. 2019), 30 pages. doi:10.1145/3371075
-
[7]
Gilles Barthe, Benjamin Grégoire, Vincent Laporte, and Swarn Priya. 2021. Structured leakage and applications to cryp- tographic constant-time and cost. InProceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security. 462–476
2021
-
[8]
Digital twins in health care: ethical implications of an emerging engineering paradigm,
Gilles Barthe, Benjamin Grégoire, and Vincent Laporte. 2018. Secure Compilation of Side-Channel Countermeasures: The Case of Cryptographic “Constant-Time”. In2018 IEEE 31st Computer Security Foundations Symposium (CSF). 328–343. doi:10.1109/CSF.2018.00031
-
[9]
Gilles Barthe, Tamara Rezk, and Amitabh Basu. 2007. Security types preserving compilation.Computer Languages, Systems & Structures33, 2 (2007), 35–59. doi:10.1016/j.cl.2005.05.002
-
[10]
Gilles Barthe, Tamara Rezk, Alejandro Russo, and Andrei Sabelfeld. 2010. Security of multithreaded programs by compilation.ACM Trans. Inf. Syst. Secur.13, 3, Article 21 (July 2010), 32 pages. doi:10.1145/1805974.1805977
-
[11]
Claudio Canella, Daniel Genkin, Lukas Giner, Daniel Gruss, Moritz Lipp, Marina Minkin, Daniel Moghimi, Frank Piessens, Michael Schwarz, Berk Sunar, Jo Van Bulck, and Yuval Yarom. 2019. Fallout: Leaking Data on Meltdown- resistant CPUs. InProceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security(London, United Kingdom)(CCS ’19)....
-
[12]
Minki Cho, Youngju Song, Dongjae Lee, Lennard Gäher, and Derek Dreyer. 2023. Stuttering for Free.Proc. ACM Program. Lang.7, OOPSLA2, Article 281 (Oct. 2023), 28 pages. doi:10.1145/3622857
-
[13]
Arthur Correnson and Bernd Finkbeiner. 2025. Coinductive Proofs for Temporal Hyperliveness.Proc. ACM Program. Lang.9, POPL, Article 53 (Jan. 2025), 28 pages. doi:10.1145/3704889 24 Arthur Correnson, Haoyi Zeng, and Jana Hofmann
-
[14]
Arthur Correnson, Iona Kuhn, and Bernd Finkbeiner. 2025. Almost Fair Simulations.Proc. ACM Program. Lang.9, ICFP, Article 243 (Aug. 2025), 24 pages. doi:10.1145/3747512
-
[15]
Brijesh Dongol, Matt Griffin, Andrei Popescu, and Jamie Wright. 2024. Relative Security: Formally Modeling and (Dis)Proving Resilience Against Semantic Optimization Vulnerabilities. In37th IEEE Computer Security Foundations Symposium, CSF 2024, Enschede, Netherlands, July 8-12, 2024. IEEE, 403–418. doi:10.1109/CSF61375.2024.00027
-
[16]
Mohammad Rahmani Fadiheh, Johannes Müller, Raik Brinkmann, Subhasish Mitra, Dominik Stoffel, and Wolfgang Kunz. 2020. A Formal Approach for Detecting Vulnerabilities to Transient Execution Attacks in Out-of-Order Processors. In2020 57th ACM/IEEE Design Automation Conference (DAC). 1–6. doi:10.1109/DAC18072.2020.9218572
-
[17]
Alameldeen, Marco Guarnieri, Mark Silberstein, Oleksii Oleksenko, and Gururaj Saileshwar
Bo Fu, Leo Tenenbaum, David Adler, Assaf Klein, Arpit Gogia, Alaa R. Alameldeen, Marco Guarnieri, Mark Silberstein, Oleksii Oleksenko, and Gururaj Saileshwar. 2025. AMuLeT: Automated Design-Time Testing of Secure Speculation Countermeasures. InProceedings of the 30th ACM International Conference on Architectural Support for Programming Languages and Opera...
-
[18]
Lennard Gäher, Michael Sammler, Simon Spies, Ralf Jung, Hoang-Hai Dang, Robbert Krebbers, Jeehoon Kang, and Derek Dreyer. 2022. Simuliris: a separation logic framework for verifying concurrent program optimizations.Proc. ACM Program. Lang.6, POPL, Article 28 (Jan. 2022), 31 pages. doi:10.1145/3498689
-
[19]
Marco Guarnieri, Boris Köpf, José F Morales, Jan Reineke, and Andrés Sánchez. 2020. Spectector: Principled detection of speculative information flows. In2020 IEEE Symposium on Security and Privacy (SP). IEEE, 1–19
2020
-
[20]
Marco Guarnieri, Boris Köpf, Jan Reineke, and Pepe Vila. 2021. Hardware-Software Contracts for Secure Speculation. In2021 IEEE Symposium on Security and Privacy (SP). IEEE
2021
-
[21]
Jana Hofmann, Emanuele Vannacci, Cedric Fournet, Boris Kopf, and Oleksii Oleksenko. 2023. Speculation at Fault: Modeling and Testing Microarchitectural Leakage of CPU Exceptions. In32nd USENIX Security Symposium (USENIX Security 23). USENIX Association, Anaheim, CA, 7143–7160. https://www.usenix.org/conference/usenixsecurity23/ presentation/hofmann
2023
-
[22]
Chung-Kil Hur, Georg Neis, Derek Dreyer, and Viktor Vafeiadis. 2013. Paco: A Coq Library for Parameterized Coinduction. https://plv.mpi-sws.org/paco/
2013
-
[23]
Chung-Kil Hur, Georg Neis, Derek Dreyer, and Viktor Vafeiadis. 2013. The power of parameterization in coinductive proof. InProceedings of the 40th Annual ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages (Rome, Italy)(POPL ’13). Association for Computing Machinery, New York, NY, USA, 193–206. doi:10.1145/2429069. 2429093
-
[24]
Ralf Jung, David Swasey, Filip Sieczkowski, Kasper Svendsen, Aaron Turon, Lars Birkedal, and Derek Dreyer. 2015. Iris: Monoids and Invariants as an Orthogonal Basis for Concurrent Reasoning. InProceedings of the 42nd Annual ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages(Mumbai, India)(POPL ’15). Association for Computing Machinery, Ne...
-
[25]
Paul Kocher, Jann Horn, Anders Fogh, Daniel Genkin, Daniel Gruss, Werner Haas, Mike Hamburg, Moritz Lipp, Stefan Mangard, Thomas Prescher, Michael Schwarz, and Yuval Yarom. 2019. Spectre Attacks: Exploiting Speculative Execution. In2019 IEEE Symposium on Security and Privacy (SP). 1–19. doi:10.1109/SP.2019.00002
-
[26]
Moritz Lipp, Michael Schwarz, Daniel Gruss, Thomas Prescher, Werner Haas, Anders Fogh, Jann Horn, Stefan Mangard, Paul Kocher, Daniel Genkin, Yuval Yarom, and Mike Hamburg. 2018. Meltdown: Reading Kernel Memory from User Space. In27th USENIX Security Symposium (USENIX Security 18)
2018
-
[27]
D. McCullough. 1988. Noninterference and the composability of security properties. InProceedings. 1988 IEEE Symposium on Security and Privacy (S&P’88). 177–186. doi:10.1109/SECPRI.1988.8110
-
[28]
Gideon Mohr, Marco Guarnieri, and Jan Reineke. 2024. Synthesizing Hardware-Software Leakage Contracts for RISC-V Open-Source Processors(DATE’24). 1–6
2024
-
[29]
Oleksii Oleksenko, Christof Fetzer, Boris Köpf, and Mark Silberstein. 2022. Revizor: Testing Black-box CPUs against Speculation Contracts. In27th ACM International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS ’22). ACM
2022
-
[30]
Oleksii Oleksenko, Marco Guarnieri, Boris Kopf, and Mark Silberstein. 2023. Hide and Seek with Spectres: Efficient discovery of speculative information leaks with random testing . In2023 IEEE Symposium on Security and Privacy (SP). IEEE Computer Society, Los Alamitos, CA, USA, 1737–1752. doi:10.1109/SP46215.2023.10179391
-
[31]
Marco Patrignani and Deepak Garg. 2017. Secure Compilation and Hyperproperty Preservation. In2017 IEEE 30th Computer Security Foundations Symposium (CSF). 392–404. doi:10.1109/CSF.2017.13
-
[32]
Marco Patrignani and Marco Guarnieri. 2021. Exorcising Spectres with Secure Compilers. InProceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security(Virtual Event, Republic of Korea)(CCS ’21). Association for Computing Machinery, New York, NY, USA, 445–461. doi:10.1145/3460120.3484534
-
[33]
Damien Pous. 2007. Complete Lattices and Up-To Techniques. InProgramming Languages and Systems, Zhong Shao (Ed.). Springer Berlin Heidelberg, Berlin, Heidelberg, 351–366. A Deductive System for Contract Satisfaction Proofs 25
2007
-
[34]
Damien Pous. 2016. Coinduction All the Way Up. InProceedings of the 31st Annual ACM/IEEE Symposium on Logic in Computer Science(New York, NY, USA)(LICS ’16). Association for Computing Machinery, New York, NY, USA, 307–316. doi:10.1145/2933575.2934564
-
[35]
Julian Rosemann, Sebastian Hack, and Deepak Garg. 2025. Non-interference Preserving Optimising Compilation.Proc. ACM Program. Lang.9, OOPSLA2, Article 323 (Oct. 2025), 26 pages. doi:10.1145/3763101
-
[36]
DAVIDE SANGIORGI. 1998. On the bisimulation proof method.Mathematical Structures in Computer Science8, 5 (1998), 447–479. doi:10.1017/S0960129598002527
-
[37]
Michael Schwarz, Moritz Lipp, Daniel Moghimi, Jo Van Bulck, Julian Stecklina, Thomas Prescher, and Daniel Gruss
-
[38]
ZombieLoad: Cross-Privilege-Boundary Data Sampling. InProceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security(London, United Kingdom)(CCS ’19). Association for Computing Machinery, New York, NY, USA, 753–768. doi:10.1145/3319535.3354252
-
[39]
Lucas Silver, Paul He, Ethan Cecchetti, Andrew K. Hirsch, and Steve Zdancewic. 2023. Semantics for Noninterference with Interaction Trees. In37th European Conference on Object-Oriented Programming (ECOOP 2023) (Leibniz International Proceedings in Informatics (LIPIcs), Vol. 263), Karim Ali and Guido Salvaneschi (Eds.). Schloss Dagstuhl – Leibniz- Zentrum ...
-
[40]
Qinhan Tan, Yuheng Yang, Thomas Bourgeat, Sharad Malik, and Mengjia Yan. 2025. RTL Verification for Secure Spec- ulation Using Contract Shadow Logic. InProceedings of the 30th ACM International Conference on Architectural Support for Programming Languages and Operating Systems, Volume 1(Rotterdam, Netherlands)(ASPLOS ’25). Association for Computing Machin...
-
[41]
Alfred Tarski. 1955. A lattice-theoretical fixpoint theorem and its applications. (1955)
1955
-
[42]
Daniël Trujillo, Johannes Wikner, and Kaveh Razavi. 2023. INCEPTION: exposing new attack surfaces with training in transient execution. InProceedings of the 32nd USENIX Conference on Security Symposium(Anaheim, CA, USA)(SEC ’23). USENIX Association, USA, Article 409, 18 pages
2023
-
[43]
Wenisch, Yuval Yarom, and Raoul Strackx
Jo Van Bulck, Marina Minkin, Ofir Weisse, Daniel Genkin, Baris Kasikci, Frank Piessens, Mark Silberstein, Thomas F. Wenisch, Yuval Yarom, and Raoul Strackx. 2018. Foreshadow: extracting the keys to the intel SGX kingdom with transient out-of-order execution. InProceedings of the 27th USENIX Conference on Security Symposium(Baltimore, MD, USA)(SEC’18). USE...
2018
-
[44]
Jo Van Bulck, Daniel Moghimi, Michael Schwarz, Moritz Lippi, Marina Minkin, Daniel Genkin, Yuval Yarom, Berk Sunar, Daniel Gruss, and Frank Piessens. 2020. LVI: Hijacking Transient Execution through Microarchitectural Load Value Injection. In2020 IEEE Symposium on Security and Privacy (SP). 54–72. doi:10.1109/SP40000.2020.00089
-
[45]
Sören van der Wall and Roland Meyer. 2025. SNIP: Speculative Execution and Non-Interference Preservation for Compiler Transformations.Proc. ACM Program. Lang.9, POPL, Article 51 (Jan. 2025), 30 pages. doi:10.1145/3704887
-
[46]
Stephan van Schaik, Alyssa Milburn, Sebastian Österlund, Pietro Frigo, Giorgi Maisuradze, Kaveh Razavi, Herbert Bos, and Cristiano Giuffrida. 2019. RIDL: Rogue In-Flight Data Load. In2019 IEEE Symposium on Security and Privacy (SP). 88–105. doi:10.1109/SP.2019.00087
-
[47]
Zilong Wang, Gideon Mohr, Klaus Gleissenthall, Jan Reineke, and Marco Guarnieri. 2025. Synthesis of Sound and Precise Leakage Contracts for Open-Source RISC-V Processors
2025
- [48]
-
[49]
Pierce, and Steve Zdancewic
Li-yao Xia, Yannick Zakowski, Paul He, Chung-Kil Hur, Gregory Malecha, Benjamin C. Pierce, and Steve Zdancewic
-
[50]
Interaction trees: representing recursive and impure programs in Coq.Proc. ACM Program. Lang.4, POPL, Article 51 (Dec. 2019), 32 pages. doi:10.1145/3371119
-
[51]
Yannick Zakowski, Paul He, Chung-Kil Hur, and Steve Zdancewic. 2020. An equational theory for weak bisimulation via generalized parameterized coinduction. InProceedings of the 9th ACM SIGPLAN International Conference on Certified Programs and Proofs(New Orleans, LA, USA)(CPP 2020). Association for Computing Machinery, New York, NY, USA, 71–84. doi:10.1145...
-
[52]
∈bisim∧ (𝑠 ′ 1, 𝑠2, ℎ1, ℎ2) ∈𝑅} H-Leak-Eq 𝑓(𝑅)≜{ (𝑠 1, 𝑠2, ℎ1, ℎ2) | (ℎ 1, ℎ′
-
[53]
∈bisim∧ (𝑠 1, 𝑠2, ℎ1, ℎ′
-
[54]
∈𝑅} Reduce-C-Leakage 𝑓(𝑅)≜{ (𝑠 1, 𝑠2, ℎ1, ℎ2) | (𝑠 1, 𝑠2, 𝑠′ 1, 𝑠′
-
[55]
∈rbisim∧ (𝑠 ′ 1, 𝑠′ 2, ℎ1, ℎ2) ∈𝑅} Augment-H-Leakage 𝑓(𝑅)≜{ (𝑠 1, 𝑠2, ℎ1, ℎ2) | (ℎ ′ 1, ℎ′ 2, ℎ1, ℎ2) ∈rbisim lockstep ∧ (𝑠 1, 𝑠2, ℎ′ 1, ℎ′
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.