arXiv subjects

Anton Sokolov

Publications and source records attributed to Anton Sokolov.

8 recordsLinked to original sources

arXiv2026

Who Assures the Verifier? An Executable Assurance-Locus Audit of the European Digital Identity Wallet

The European Digital Identity Wallet (EUDI Wallet) architecture places material duties on relying parties: they register services and intended uses, authenticate to Wallet Units, validate presentations and trust anchors, and make risk-based status decisions. Wallet certification and the emerging Functional Conformance Assessment Framework provide increasingly structured wallet-side evidence. A different question remains: what independently rerunnable evidence shows that the concrete relying-party verifier version used in a transaction enforced the applicable request, presentation and reliance-decision controls? We conduct an assurance-locus audit of current law, Architecture and Reference Framework (ARF) 3.0.0, ETSI metadata, FCAF scope and three pinned open-source verifier codebases. We then design a 17-rule research profile, a machine-readable evidence receipt and 36 frozen synthetic transactions. Three heterogeneous study-authored implementations (Python, JavaScript and jq) execute 108 cases with zero oracle mismatches and zero cross-path disagreements. The experiment establishes determinism and implementability of the proposed decision model, not product conformance or certification. Source inspection finds substantial protocol-verification mechanisms in all three public codebases but no single audited evidence object joining RP registration and purpose, exact verifier/policy version, transaction verdict and downstream attribute use. We therefore propose an RP-as-system-under-test evidence unit that complements, rather than displaces, wallet certification, registration and supervision. A preregistered census of 26 appointed experts is prepared to test content validity and governance feasibility; recruitment awaits the applicable ethics/data-protection determination.

cs.CR↗

arXiv2026

A Challenge-Nonce Freshness Gap in Project Veraison's TPM Reference Schemes, Found by Appraising Application-Layer Action Evidence End-to-End

When an automated agent (an AI agent, say) takes a consequential action, the record it leaves behind is produced by the very software stack whose integrity is in question. A signed log proves which key wrote the record, not what the runtime was. Prior work proposed treating that record (an Action Evidence Package, AEP: a signed append-only record of an action, its authorising principal, and its outcome) as application-layer Evidence under the IETF Remote ATtestation procedureS (RATS) architecture (RFC 9334), binding the outcome into a hardware-rooted TPM quote so that swapping it invalidates the quote. But that prior work appraised the result only against a minimal Verifier stand-in. This article closes that gap. We drive an AEP quote, produced on an emulated software TPM, end-to-end through a conformant Project Veraison RATS Verifier. We generate an EC P-256 attestation key, measure the AEP outcome digest into a PCR, pack a genuine quote into Veraison's tpm-enacttrust format, provision a Concise Reference Integrity Manifest (trust anchor plus golden reference value), and obtain a signed EAT Attestation Result (EAR). Good evidence yields affirming; an outcome-swap or a one-byte signature tamper yields contraindicated. Along the way we uncover, responsibly disclose, and fix a security-relevant finding: the reference scheme does not enforce challenge-nonce freshness, so a replayed quote still appraises as affirming. We give an exact, upstreamable two-part fix and validate it end-to-end. With the fix active, the same valid quote that is affirming in its own session flips to contraindicated when replayed to a fresh one. The pipeline is fully reproducible; the Attester remains an emulated swtpm, not a hardware guarantee.

cs.CR↗

arXiv2026

Hardware-rooted attestation for AI-agent evidence: composing IETF RATS with action evidence packages

An action evidence package (AEP) is a signed, append-only record of what an AI agent did, who or what authorised the action, and what the outcome was. It is a software-layer artefact: it tells a verifier the story of an action as the agent's own runtime reports it. This note argues that software attestation of this kind is necessary but not sufficient. When a verifier's question shifts from "what does the agent claim it did?" to "did the specific model version the operator claims to have deployed actually produce this output, on unmodified hardware?", the AEP alone cannot answer. The missing element is a hardware root of trust: an attestation that the measured boot and runtime state of the platform match an endorsed reference. The IETF Remote Attestation Procedures (RATS) architecture (RFC 9334) and Veraison, an open-source RATS Verifier implementation (Confidential Computing Consortium / Linux Foundation), supply exactly this. We propose a composite attestation: hardware Evidence appraised under RATS, bound to a software AEP. We map a small verifier vocabulary (Authorised / Unauthorised / Indeterminate / Attested / Contested / Expired) onto RATS appraisal outcomes, and demonstrate feasibility with a small executed experiment: on a software Trusted Platform Module (TPM; the swtpm emulator), an output-binding protocol folds the hash of an AEP outcome and a fresh appraiser nonce into an attestation-key-signed quote, with a model-artefact measurement carried in a platform register. A minimal RATS-Verifier stand-in resolves the three platform outcomes as designed -- Attested for a good, fresh quote; Contested when the model measurement is swapped; Expired when a stale quote is replayed -- and rejects a forged AEP outcome bound to a valid quote. The result is a feasibility demonstration on emulated hardware, not a hardware-rooted guarantee.

cs.CR↗

arXiv2025

Stellar cooling limits on KK gravitons and dark dimensions

We revisit cooling bounds on light Kaluza-Klein (KK) gravitons, as arise in the dark dimension scenario, considering red giants, neutron stars, and supernovae. In addition to bremsstrahlung, we account for two novel production channels: resonant mixing with the in-medium photon and a pion-induced process in supernovae. The strongest limits arise from SN 1987A, with the emissivity from the pion process exceeding that from bremsstrahlung by a factor of a few. Given present uncertainties, we obtain a bound on the KK mass scale of $m_{\rm KK}\gtrsim 0.6\,{\rm eV}$ $(\gtrsim 500\,{\rm eV})$ for 2 (3) extra dimensions. Improved understanding of the properties of pions in supernovae could strengthen these limits to roughly ${\rm eV}$ $({\rm keV})$. For 1 extra dimension, the bounds are weaker than those from laboratory searches. We also show that constraints from KK graviton decays to Standard Model particles are less stringent than the cooling bounds if there is KK number violation at the level typically assumed in the dark dimension scenario, although these bounds could be strengthened by future observations.

hep-ph↗

arXiv2025

Supernova bounds on new scalars from resonant and soft emission

We study supernova cooling constraints on new light scalars that mix with the Higgs, couple only to nucleons, or couple only to leptons. We show that in all these cases scalars with masses smaller than the plasma frequency in the supernova core are efficiently produced by resonant mixing with the in-medium longitudinal degree of freedom of the photon. The resulting bounds are free from uncertainties associated to the rate of emission of the scalar in nucleon-nucleon scatterings, which would otherwise badly affect the Higgs-mixed and nucleophilic scenarios. Heavier scalars that mix with the Higgs or couple only to nucleons are mostly produced by nucleon bremsstrahlung, and we obtain a conservative approximation for the corresponding rate using a soft theorem. We also analyse the impact of different supernova profiles, nucleon degeneracy, trapping and scalar decays on the constraints.

hep-ph↗

arXiv2023

Sensitivity of Resonant Axion Haloscopes to Quantum Electromagnetodynamics

Recently interactions between putative axions and magnetic monopoles have been revisited by two of us [arXiv:2205.02605 [hep-ph]]. It has been shown that significant modifications to conventional axion electrodynamics arise due to these interactions, so that the axion-photon coupling parameter space is expanded from one parameter $g_{aγγ}$ to three $(g_{aγγ},g_{aAB},g_{aBB})$. We implement Poynting theorem to determine how to exhibit sensitivity to $g_{aAB}$ and $g_{aBB}$ using resonant haloscopes, allowing new techniques to search for axions and a possible indirect way to determine if magnetically charged matter exists.

hep-ph↗

arXiv2021

Reconciling hints on axion-like-particles from high-energy gamma rays with stellar bounds

It has been recently claimed by two different groups that the spectral modulation observed in gamma rays from Galactic pulsars and supernova remnants can be due to conversion of photons into ultra-light axion-like-particles (ALPs) in large-scale Galactic magnetic fields. While we show the required best-fit photon-ALP coupling, $g_{aγ} \sim 2 \times 10^{-10}$ GeV${}^{-1}$, to be consistent with constraints from observations of photon-ALPs mixing in vacuum, this is in conflict with other bounds, specifically from the CAST solar axion limit, from the helium-burning lifetime in globular clusters, and from the non-observations of gamma rays in coincidence with SN 1987A. In order to reconcile these different results, we propose that environmental effects in matter would suppress the ALP production in dense astrophysical plasma, allowing to relax previous bounds and make them compatible with photon-ALP conversions in the low-density Galactic medium. If this explanation is correct, the claimed ALP signal would be on the reach of next-generations laboratory experiments such as ALPS II.

hep-ph↗

arXiv2015

Constraining spacetime variations of nuclear decay rates from light curves of type Ia supernovae

The luminosity of fading type Ia supernovae is governed by radioactive decays of 56Ni and 56Co. The decay rates are proportional to the Fermi coupling constant G_F and, therefore, are determined by the vacuum expectation value v of the Brout-Englert-Higgs field. We use publicly available sets of light curves of type Ia supernova at various redshifts to constrain possible spacetime variations of the 56Ni decay rate. The resulting constraint is not very tight; however, it is the only direct bound on the variation of the decay rate for redshifts up to z~1. We discuss potential applications of the result to searches for non-constancy of G_F and v.

hep-ph↗