Cryptography and Security · Cross-listed from cs.CY
Using Codebooks to Detect Cybercrime Topics in Text Narratives
Shufan Chai, Liangliang Sun and Jessica Staddon
In the United States, management of cybercrime-related consumer complaints increasingly falls on state and city governments given de-staffing of federal agencies. AI, and in particular, large
language models (LLMs), shows promise for detecting cybercrime in text complaints, but often via specialized models that local governments are not resourced to develop and maintain. We present an LLM prompting method that uses codebooks from qualitative cybercrime research to detect cybercrime topics in consumer narratives. For two cybercrime topics, impostor scams and identity theft, we demonstrate the method achieves high precision and recall across multiple runs of 5 models in the Gemini and GPT model families. This strategy suggests a path for resource-constrained organizations, like many local governments, to leverage frontier models to support community safety.
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Cryptography and Security
Decentralized Compute on Untrusted Hardware Using Intel TDX and Encrypted CVMs
Venish Patidar, Dhruv Bindra, Ahmed Darwich et al. (+3 more)
The rapid growth of artificial intelligence workloads has generated an unprecedented demand for secure and scalable compute resources. However, centralized cloud providers continue to dominate both pricing and security models. In an increasingly competitive AI landscape, where the compromise of training data or model weights can confer a significant advantage, there is a critical need for a computing infrastructure that safeguards data at rest, in transit, and in use, while remaining affordable and broadly accessible. Furthermore, existing GPU cluster offerings (e.g., 8xH100s, 8xH200s, 8xB200s) create financial barriers that limit access for organizations, startups, and independent researchers seeking secure, high-performance computing environments. This paper introduces a decentralized, confidential computing platform that leverages Intel Trust Domain Extensions (TDX), Intel Trust Authority (ITA) and NVIDIA Confidential Computing (CC) to establish a distributed ecosystem of fully encrypted Confidential Virtual Machines (CVMs). The proposed architecture incentivizes hardware providers to contribute Intel TDX capable compute resources. Each participating provider is provisioned with a freshly instantiated, uniquely encrypted Ubuntu 24.04 CVM, providing data protection across all stages, at rest, in transit, and in use. By decentralizing the confidential computing stack and leveraging confidential computing across independently operated nodes, this work demonstrates a viable alternative to traditional cloud-based infrastructures. The proposed system offers enhanced security assurances, transparent cost structures, and democratized access to enterprise-grade secure compute capabilities, paving the way for a more open, secure, and equitable foundation for next-generation AI development.
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All authors Venish Patidar, Dhruv Bindra, Ahmed Darwich, Josh Brown, Haidong Xia, Sathi Nair
Cryptography and Security
Certified in Theory, Broken in Practice: Assumption Gaps in Cryptographic Model Certification
Carter Luck, Olive Franzese-McLaughlin, Elisaweta Masserova et al. (+3 more)
Privacy-preserving machine learning auditing protocols allow auditors to assess models for properties such as accuracy or
fairness, without revealing their internals or training data. This makes them especially attractive for auditing models deployed in sensitive domains such as healthcare or finance. For these protocols to be meaningful in real-world audit settings, though, their guarantees must reflect how the model will behave once deployed, rather than merely certifying its behavior during an audit. Existing security definitions often miss this mark: most certify model behavior only on a fixed audit
dataset, without ensuring that the same guarantees generalize to other
datasets drawn from the same distribution. As we show, this gap allows a model provider to attack many cryptographic model certification (CMC) schemes built on secure zero knowledge proofs (ZKP) by carefully engineering training data, resulting in models that exhibit benign behavior during an audit, but pathological behavior in practice. For example, we empirically demonstrate that an attacker can certify that a model achieves over 99% accuracy on an audit
dataset, but less than 30% accuracy on fresh samples from the same distribution. To address this gap, we formalize rigorous cryptographic security notions tailored to CMC frameworks, introduce a generic protocol template, and prove that it satisfies these requirements. Our results thus offer both cautionary evidence about existing approaches and constructive guidance for designing secure,
privacy-preserving ML auditing protocols.
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All authors Carter Luck, Olive Franzese-McLaughlin, Elisaweta Masserova, Akira Takahashi, Antigoni Polychroniadou, Nicolas Papernot
Cryptography and Security
ToolGuardian: Declarative Security for AI Agent-Tool Interactions
Arun Ravindran and Saurabh Deochake
LLM
agents increasingly rely on external tools, expanding capability while creating a new security boundary: third-party tools may appear benign at the interface level while
embedding unsafe behavior in implementation. Existing defenses rely on weak metadata, collapse characterization and policy judgment into a single decision, or use heuristic/LLM enforcement that lacks deterministic, auditable
reasoning over task context and multi-tool composition. This paper presents ToolGuardian, a policy-driven framework for securing
agent-tool interactions through pre-admission vetting and task-aware runtime authorization. ToolGuardian uses progressive characterization to convert evidence into structured facts: descriptions capture declared intent, system-call traces expose coarse behavior, mock execution reveals observed effects, and source analysis identifies latent behavior. ToolGuardian's core contribution is an Answer Set Programming (ASP)-based declarative policy layer that reasons explicitly over capabilities, effects, task context, and composition. We compare ASP against heuristic and LLM-based policy realizations using identical inputs and output contracts. We evaluate ToolGuardian on 16 MCP-style tools, including 8 malicious variants derived from real open-source tools, and 20 runtime scenarios. For vetting, ASP reaches a deny-class F1 of 0.86 and 88% accuracy using description, syscall, and observed-effect evidence. For runtime authorization, fully specified realizations classify all scenarios correctly, while ablations show that removing compositional and conformance rules substantially degrades performance.
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Cryptography and Security
Protocol-Level Attacks on Agentic Commerce Platforms: A Cross-Platform Taxonomy, AIP-Bench, and Unified Defense
Yedidel Louck
Agentic commerce platforms let AI
agents autonomously discover services, move payments, and wield user credentials on their users' behalf, and they already handle real money. Their security has so far been studied almost entirely at the level of the AI model, through
prompt injection and misalignment. We show that the more consequential risks lie one layer down, in the protocol between
agents and commerce services. There, vulnerabilities are structural : exploitation is deterministic and ndependent of which model an
agent runs, so no model improvement removes them. Across three leading platforms we identify 33 such vulnerabilities, each succeeding deterministically regardless of the deployed model, at a 100% attack-success rate (ASR) wherever live-measured. The same failure modes recur across independently built codebases, a systemic pattern rather than isolated bugs. Three of them chain into an end-to-end payment hijack. We contribute a taxonomy separating these structural attacks from model-dependent semantic ones. We also build two artifacts: AIP-Bench (
Agent Interaction Protocol
Benchmark), to our knowledge the first deterministic
benchmark for agentic commerce security, and PCAT (Protocol-level Commerce
Agent Trust), a platform-agnostic defense that drives the structural attack-success rate to zero for four of the five structural classes (RC-1, RC-2, RC-4, RC-5), with RC-3 (observable credential channels) reduced to warn-only, without modifying any platform. Agentic commerce must be secured at the protocol layer, not only the model.
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Cryptography and Security · Cross-listed from cs.SD
Probing Speaker Identity Sensitivity in Audio Deepfake Detectors
Daniyal Kabir Dar and Arun Ross
Audio deepfake detectors are trained to distinguish genuine
speech from synthetic
speech and often perform well on standard
benchmarks. Yet the same detector that achieves less than 1% error on one
dataset can see its error rate increase twentyfold when evaluated on a different
dataset. We argue that one contributing factor is speaker-identity reliance: standard training corpora correlate speaker identity with the genuine/synthetic label, allowing detectors to partially rely on speaker-related cues rather than synthesis artifacts alone. We propose the Identity Sensitivity Score (ISS), a per-utterance diagnostic that quantifies how much a detector's output changes across different speaker identity contexts. ISS requires no ground-truth labels at inference time and can be computed from the detector score and a pool of reference speaker examples. Across two detectors and two
datasets, incorrectly classified utterances have ISS scores 29 to 52 times higher than correctly classified utterances, and ISS alone predicts misclassification with area-under-curve (AUC) up to 0.954. To test whether ISS actually captures identity-sensitive behavior rather than serving only as a proxy for prediction confidence, we apply voice conversion to 500 utterances and measure the resulting detector-score shift. Utterances flagged as identity-sensitive by ISS respond 19 to 30 times more strongly to this manipulation than utterances flagged as stable. These results position ISS as a practical inference-time diagnostic for speaker-dependent failure analysis in audio deepfake detection.
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Cryptography and Security · Cross-listed from quant-ph
Efficient Unclonable Encryption from Pauli Eigenstates
Seyoon Ragavan
We give, to our knowledge, the first plain-model, one-time information-theoretically secure, efficient unclonable encryption scheme for one classical bit. Previous work by Bhattacharyya and Culf (Nature Physics, 2026) and Bhattacharyya, Broadbent, and Culf either only showed $1/\mathsf{poly}(\lambda)$ security loss or required inefficient encryption/decryption operations. We avoid both of these caveats; in doing so, we obtain (to our knowledge) the first plain-model construction of many-time secure $1 \to 2$ unclonable encryption for arbitrary
polynomial-length messages, assuming the existence of pseudorandom function-like states (Bartusek and Goldin). The key is a uniformly random non-identity phase-free Pauli on $n$
qubits, and bit $a$ is encrypted as a random $(-1)^a$ eigenstate of that Pauli. The scheme is exponentially secure; we prove that the probability that both receivers recover the bit is at most $\frac{1}{2}+\frac{1}{2}\sqrt{{2^n}/({4^n-1})} = \frac{1}{2} + O\left(2^{-n/2}\right).$ By a lower bound due to Broadbent, Culf, and Rochette, this is the best probability bound achievable with $n$-
qubit ciphertexts (up to the constant hidden in the $O(\cdot)$). The main conceptual idea is to leverage, in a precise spectral sense, the balanced commutation-anticommutation structure of the Pauli group. The proof is intricate but completely elementary and makes use of standard spectral bound techniques. The main technical workhorse is a standalone linear-algebraic lemma that informally relates the positivity of two different operators, each capturing the intuition that if the two receivers can individually decrypt unusually often then they must also disagree often. GPT-5.6 Sol Ultra found this proof in an extended conversation with the author and drafted a preliminary version of this paper. The author is fully accountable for the correctness of this paper.
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Cryptography and Security
Adversarial Prompts for Acceptance Collapse in Speculative Decoding
Run Wang, Chaoyi Zhou, Xi Liu et al. (+7 more)
Lossless acceleration schemes, such as speculative decoding, promise significant inference speedups by relying on dynamic
token-level
alignment between a draft and a target model. However, this guarantee of semantic equivalence masks a severe operational vulnerability: draft-target
alignment can be systematically attacked. In this paper, we introduce ADSD, which, to the best of our knowledge, is the first
prompt-suffix attack that collapses verifier acceptance by pushing draft probability mass toward
tokens the target is unlikely to accept. ADSD uses Soft-Collapse, a verifier-aligned surrogate derived from the asymmetric speculative acceptance rule, together with a target-preservation objective that discourages obvious task corruption. ADSD successfully generates highly effective
adversarial suffixes. On the GSM8K
dataset, our attack increases the mean sample time by 62.3% while preserving the task quality. We further show that this vulnerability exists across different domains, speculative decoding strategies, and model architectures.
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All authors Run Wang, Chaoyi Zhou, Xi Liu, Yi Zhu, Amir Salarpour, Pedram MohajerAnsari, Zhi-Qi Cheng, Feng Luo, Siyu Huang, Mert D. Pesé
Cryptography and Security · Cross-listed from cs.LG
Physiological Signals as a Forensic Modality for Talking-Face Deepfake Detection
Othmane Harraq and Tamer Aldwairi
Talking-face (TF) deepfake generation synthesizes photore- alistic facial
video from a static source image and an au- dio signal, producing forgeries that current image-based detectors consistently fail to identify. Unlike face-swap ma- nipulation, TF synthesis has no underlying real
video from which to inherit physiological characteristics, making re- mote photoplethysmography (rPPG) a uniquely motivated detection modality for this forgery category. We propose a detection framework that extracts per-
video rPPG wave- forms via RhythmFormer and trains a suite of lightweight classifiers to distinguish real from synthesized physiologi- cal signals. Evaluated on the TF subset of Celeb-DF++ un- der a strict subject-independent protocol, where test identi- ties are completely separated from training identities, our 1D ResNet achieves an AUC of 0.806 and EER of 27.8%, placing it within 2.4 points of the best published general- purpose detector (Effort, ICML 2025) while operating ex- clusively on the physiological channel. We document a con- trolled reproduction study of DeepFakesON-Phys, the rep- resentative prior rPPG detector, demonstrating degrada- tion from AUC 0.999 on legacy face-swap data to 0.622 on the TF subset of Celeb-DF++. We further show that detec- tion difficulty is strongly method-dependent: AUC ranges from 0.985 (Real3DPortrait) to 0.690 (IP-LAP) across the seven TF generators, with the ranking remaining perfectly stable across all evaluation protocols. This spread reflects an interpretable physiological property of each generator rather than evaluation noise, and constitutes the primary theoretical contribution of the work.
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Cryptography and Security
Every Model Cheats: Prompt-Level Mitigation of Cheating on Offensive Cyber Tasks
Michael Kouremetis, Ads Dawson, Raja Sekhar Rao Dheekonda et al. (+1 more)
Large
language model (LLM)
agents routinely cheat on cybersecurity
benchmarks, inflating reported pass rates far beyond genuine capability. Prior audits of Cybench found cheating in 0.3-3.4% of traces, implicating only a handful of models. We present a controlled
prompt-ablation study across 22 frontier models from 7 providers on 23 Cybench capture-the-flag (CTF) challenges under three
prompt conditions (no anti-cheat, standard, severe). All 1,518 task traces were individually audited through a four-stage pipeline combining LLM-as-a-judge classification, programmatic verification, judge-verifier reconciliation, and human review. We find cheating is far more pervasive than previously estimated: under baseline conditions, 37.1% of passes involved cheating, 21 of 22 models cheated, and scores were inflated by up to 5x. Anti-cheat
prompts reduce cheat propensity from 33.0% (baseline) to 18.6% (standard) to 8.5% (severe) without degrading, and sometimes improving, solve rates. However, even under the most restrictive
prompt condition, eight models still produced cheated passes, and cheating shifted from web search toward infrastructure probing. We introduce the "solve rate" metric (clean passes only) to distinguish genuine capability from cheated outcomes, and argue it should be standard practice in any evaluation where cheating vectors are available. Anti-cheat
prompts are an effective and essentially free first layer of mitigation, but they are not a substitute for environmental controls.
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All authors Michael Kouremetis, Ads Dawson, Raja Sekhar Rao Dheekonda, Brian Greunke
Cryptography and Security · Cross-listed from cs.AI
What AI Red-Team Evaluations Can and Cannot Prove
Bandana Kaur
Red-team evaluations of AI models support some claims and not others, and the boundary between the two is calculable rather than merely a matter of judgment. We define the evidential ceiling of an evaluation as the largest factor by which one result can move belief under a fixed testing budget, derive it in closed form for the
benchmark null result, and use it to locate that boundary exactly. We find that above a calculable harm rate, a
benchmark of modest size certifies a category to a stated evidentiary standard, and a clean sheet is then the stronger of the two possible observations, outweighing a single reproduced failure. Below that rate, no passive
benchmark of feasible size provides the specified evidence of safety under the fixed scoring rule and approximately independent trial structure. The crossing between the two regimes has a closed form. The bound is not specific to
benchmarks: written in terms of a procedure's hypothesis conditioned elicitation rates, it covers adaptive and automated red teaming as well, and shows that discrimination between the hypotheses rather than attack success is what determines evidential worth. Auditing eight evaluation suites against the boundary, we find that current
benchmarks are adequate for high-frequency harm categories and several orders of magnitude short for rare, catastrophic ones. Safety
benchmarks are not uninformative. They are informative about a specific and computable set of propositions, and the discipline they need is to state which.
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Cryptography and Security
A method of Risk Analysis and threat management using analytic hierarchy process
Manvi Sahni and Sumanta Kumar Das
Efficient risk analysis and threat management are essential requirements of modern air defense (AD) systems. The paper is halfway between the analytic hierarchy process (AHP) and practical
reasoning to model and analyze the risks and threats associated with military AD applications. The models are applied for decision-making tasks of AD command and control (C2) for assessing and prioritizing the threat from hostile targets for efficient risk management. The paper presents a method for threat assessment using fuzzy set theory, the AHP, and the technique for order preference by similarity to ideal solution (TOPSIS). The target threat attributes are first represented using fuzzy set theory. The experts' subjective opinions on different alternatives are quantified and ranked using the AHP process. These AHP solutions are obtained through the TOPSIS for prioritization. The models are implemented in a simulated environment. The simulated system runs without any human intervention and represents the state-of-the-art model for the C2 system. The use of fuzzy set theory, AHP, and TOPSIS for decision-making tasks is particularly useful from the point of view of futuristic risk and threat management in the battlefield. This method is easy to implement in practice and good for real-time applications.
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Cryptography and Security · Cross-listed from cs.LG
Self-Poisoning in Adaptive Out-of-Distribution Detection: A Sharp-Threshold Theory and Certified Label-Free Calibration
Vishnu Bindu Balachandran
Test-time adaptive out-of-distribution (OOD) detectors update a
memory bank from the unlabelled stream. We show this adaptation obeys a provable dynamical law. Modelling bank impurity as a generalized Pólya urn, we prove almost-sure convergence to a mean-field
equilibrium whose slope acts as a reproduction number. Below one, impurity stays benign. Above one, the bank is fully poisoned and the detector collapses. The measured admission kernel is affine ($R^2 \ge 0.996$) with slope just below one in every encoder family (a protocol signature), so this detector class is near-critical by design, and across 96 settings the predicted threshold matches the empirical collapse, where ungated dictionaries lose up to $0.163$ AUROC. We then prove that a certified admission gate, reading only a frozen reserve, severs the feedback loop and removes the transition at every contamination rate, even adversarially, while controlling false positives label-free. For the complementary static-calibration failure under drift we give CDC, which restores nominal FPR label-free on all tested drift-affected
cells. Finally we prove a two-world impossibility
theorem. Drift and contamination are indistinguishable without labels, forcing a closed-form power ceiling our procedure approaches. Together these give a complete possibility/impossibility characterization of label-free adaptive OOD detection.
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Cryptography and Security
Where You Tap Matters: A Probe-and-Model Benchmark for Open-Set RF Fingerprinting
Gabriele Oligeri, Savio Sciancalepore, Ingrid Huso et al. (+1 more)
Radio Frequency Fingerprint Identification (RFFI) enables transmitter identification at the physical layer by learning device-specific impairments from received signals, yet the literature is inconsistent about where in the receiver chain those samples should be collected. Since distinct transformations are applied to the signal by the different receiver operations, i.e., carrier recovery, gain normalization, pulse shaping, and timing recovery, they can either tighten within-transmitter variability or suppress the features RFFI requires for classification. We present a systematic real-world evaluation of open-set, reconstruction-error RFFI using data collected at five probe points along a standard BPSK receiver chain. Our results show that RFFI is strongly probe-dependent: timing recovery and, to a lesser extent, carrier recovery enable low false-acceptance operation with limited in-distribution-out-of-distribution overlap, whereas other stages often require a false-acceptance ratio above 0.1 to achieve a true-acceptance ratio of 0.9. To test the validity of our findings across model selection, we
benchmark several LLM-designed autoencoders using a controlled pipeline that holds preprocessing and MSE scoring fixed. These architectures confirm that RFFI is probe-dependent. Moreover, they do not outperform the baseline at the chosen operating point and typically increase training time. Overall, probe selection dominates reconstruction-based open-set RFFI performance, more than the autoencoder complexity.
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All authors Gabriele Oligeri, Savio Sciancalepore, Ingrid Huso, Fatima Al-Mousawi
Cryptography and Security · Cross-listed from quant-ph
Unconditional Unclonable Encryption
Prabhanjan Ananth, Seyoon Ragavan and Amit Sahai
We give an unconditional construction of information-theoretically secure one-time private-key unclonable encryption for one-bit messages, with efficient encryption and decryption and exponentially small unclonable-indistinguishability advantage. Previous work by Bhattacharyya and Culf (Nature Physics, 2026) and Bhattacharyya, Broadbent, and Culf (arXiv:2603.08916) either only showed inverse-
polynomial security loss or required inefficient encryption/decryption operations; we avoid both of these caveats. Our scheme's key is a uniformly random non-identity phase-free Pauli on $n$
qubits, and bit $a$ is encrypted as a random $(-1)^a$ eigenstate of that Pauli. We prove that the probability that both receivers recover the bit is at most $1/2 + O\left(2^{-n/2}\right).$ By a lower bound due to Broadbent, Culf, and Rochette (arXiv:2510.00903), this is the best probability bound achievable with $n$-
qubit ciphertexts while ensuring perfect correctness (up to the constant hidden in the $O(\cdot)$).
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Cryptography and Security
Themis Consensus Extension v1: MEV Mitigation by Randomized Delayed Execution and Intent-Hiding Transactions in Application-Specific Blockchains
Shoeb Siddiqui, Mateusz Nowakowski, Stanislav Vozarik et al. (+2 more)
Maximal extractable value (MEV) arises when privileged participants select, exclude, insert, or reorder pending transactions for private gain. We specify and analyze the Themis Consensus Extension v1, first published by Mangata in 2021. The design separates value extraction by reordering (VER) from value extraction by denial (VED). For VER, block construction and execution occur across consecutive producers: one producer commits a transaction set, and the next derives a publicly verifiable, deterministic, previously un- predictable seed and executes a seed-determined, dependency-preserving permutation. For selective VED, a user may encrypt a transaction for a designated builder and executor. The builder removes an outer layer and commits the opaque inner ciphertext; the executor reveals and executes the plaintext only after commitment. Under selfish but non-colluding validators, an adversary below the underlying consensus fault threshold, secure cryptography, and accountable role performance, the construction limits unilateral post-commit ordering control and hides transaction intent from relays and the builder. It does not provide send-order or receive-order
fairness, complete censorship resistance, resistance to builder-executor collusion, or per-transaction price guarantees. We analyze probabilistic extraction, spam, dependent transactions, decryption liveness, session boundaries, total denial, and threshold coalitions. We also document the initial Aura-based Substrate implementation and its subsequent transition to a BABE-based sr25519/VRF seed path, together with delayed execution, Fisher-Yates shuffling, and Xoshiro256++. The result preserves the original proposal while narrowing its claims to explicit assumptions.
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All authors Shoeb Siddiqui, Mateusz Nowakowski, Stanislav Vozarik, Gleb Urvanov, Peter Kris
Cryptography and Security
Cryptographically verifiable authorization for autonomous AI agents: a falsifiable hypothesis and proof of concept
M. Llambí-Morillas and D. Fernández-Fernández
Autonomous AI
agents increasingly execute actions, invoke tools, and operate on protected resources with limited human oversight. Existing authentication and authorization mechanisms establish identity and delegate authority but do not inherently provide cryptographic evidence that a concrete request issued by a specific
agent satisfies the applicable policy in a specific execution context. This study hypothesizes that
agent authorization can be formalized as a cryptographically verifiable relation, denoted $R_{CVA}$, that jointly binds an
agent principal, a concrete authorization request, an execution context, and the satisfaction of an applicable policy, while selectively preserving the confidentiality of private authorization attributes. We introduce a preliminary formal abstraction for Cryptographically Verifiable
Agent Authorization (CVA), define a compact set of candidate security properties including authorization soundness, principal binding, request binding, policy binding, and replay resistance, and provide an executable zero-knowledge proof of concept that instantiates selected elements of the model over a Groth16 zk-SNARK construction. We further identify and formalize the structural separation among identity binding, authorization-request binding, and runtime execution binding as a central open problem in the design of secure agentic systems, a distinction to our knowledge, has not been formalized within a cryptographically verifiable authorization relation by current agentic security frameworks, and present a falsifiable research agenda for its resolution.
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Cryptography and Security · Cross-listed from cs.GT
Advances in STV Margin Computation
Michelle Blom, Alexander Ek, Peter J. Stuckey et al. (+2 more)
Single transferable vote (STV) is a multi-winner preferential proportional electoral system. The margin is the smallest number of ballots that need to be manipulated to alter the set of winners. If we can compute the margin of an STV election, or a reasonable lower bound on the margin, we can use recent advances in auditing research to conduct a risk-limiting audit of the election's winners. Knowledge of the margin also provides insight into whether uncovered mistakes, or a known error rate in ballot interpretation, could have influenced the outcome. This paper presents substantial improvements on an existing
algorithm for computing lower bounds on the margin of an STV election. These improvements allow us to compute higher lower bounds for real STV elections, making mismatch-based risk-limiting audits more practical.
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All authors Michelle Blom, Alexander Ek, Peter J. Stuckey, Vanessa Teague, Damjan Vukcevic
Cryptography and Security · Cross-listed from cs.LG
Agree on the Model, Verify the Inference: GKR Protocols for HND-Based Transformer Inference
Xiaolong Liang, Juanjuan Li, Rui Qin et al. (+1 more)
Outsourced
Transformer inference exposes clients to model substitution and incomplete execution, while direct replay removes the computational benefit of delegation. We present GKR-HND, a registered-model protocol for verifying the
polynomial backbone of Homomorphic–Nonhomomorphic Decomposition
Transformers. The retained verifier checks the GKR transcript and registered-weight openings, but delegates expensive public evaluations to an assigned computation worker. Assuming an honest retained verifier and prover–worker non-collusion, the verifier accepts only when the worker's signed, request-bound response agrees with the proof claims. Experiments with pretrained HND models validate the proof path and the delegated public computation without dense-
matrix replay.
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All authors Xiaolong Liang, Juanjuan Li, Rui Qin, Yisheng Lv
Cryptography and Security · Cross-listed from stat.AP
Risk-Limiting Audits for Parliamentary Majorities
Jack Freestone, Dennis Leung and Damjan Vukcevic
Existing methods for risk-limiting audits typically focus on certifying individual contests. In parliamentary elections, however, the politically relevant outcome is often whether a party has won enough seats to form government, not whether every reported seat outcome is correct. Extending on the work of Mohanty et al. (2019), we formulate the certification of a parliamentary majority as a partial conjunction testing problem: it is enough to verify that the reported winning party truly won at least a majority of its reported seats. Building on the SHANGRLA auditing framework, we construct a sequential audit statistic for the majority outcome by combining seat-level statistics. We then propose adaptive sampling strategies that allocate auditing effort across seats, including variants that learn to avoid spending excessive effort on seats that appear unlikely to have been truly won. Using simulations based on synthetic and real data, from the 2014 Indian Lok Sabha election, we show that auditing the parliamentary majority can substantially reduce the number of ballots inspected (by almost a thousand-fold) compared to certifying every reported winning seat.
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Cryptography and Security · Cross-listed from cs.IT
Weak Private Information Retrieval for Graph-based Storage
Shodasakshari Vidya, Chandan Anand and Prasad Krishnan
A distributed storage system with graph-based replication consists of a collection of databases and the files they contain. The databases (or servers) are represented as the vertices of a graph, while each file is stored in a distinct pair of servers and is represented by an edge of this graph. Private information
retrieval (G-PIR) on such a graph-based storage system involves a client which seeks to retrieve a desired file via a query-response protocol, without leaking the identity of the desired file index to any database. The goal of G-PIR is to maximize the rate (reciprocal of the total normalized download) under the
privacy constraint. Prior work on G-PIR has involved perfect information-theoretic
privacy (i.e., null leakage). However, if the
privacy constraint is relaxed, then PIR protocols could be designed that have even higher rates. We term such protocols as Graph-based Weak Private Information
Retrieval (G-WPIR) protocols and initiate their formal study in this work. We propose a G-WPIR scheme for arbitrary graphs, and identify the trade-offs it achieves between rate and
privacy, under two well known leakage metrics: mutual information leakage and maximal leakage. Our protocol employs minimal subpacketization (representing a file-size constraint) and employs a simple probabilistic query realization to obtain the smooth trade-off. We extend this protocol with some modifications to two special classes of graphs, the complete graphs and the complete bipartite graphs, and identify the corresponding rate-
privacy trade-offs achieved.
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Cryptography and Security · Cross-listed from cs.DC
The Consensus Number of Untraceable Cryptocurrencies
Christian Cachin, David Lehnherr, Juan Villacis et al. (+1 more)
Sender untraceability hides the account spent by a cryptocurrency transfer among a set of candidates, its masking set. What a transfer does to that set separates two designs: classical schemes retain the whole set and append a nullifier marking the spent account, so the ledger grows with every transfer; constant-state schemes instead consume and replace the entire set. We ask how this choice affects synchronization. We formalize the two designs as the linear and constant untraceable asset transfer objects (LUAT and CUAT) and locate them in the consensus hierarchy. In LUAT, transfers from distinct accounts commute. Its consensus number is 2, compared with 1 for standard asset transfer, independently of the masking-set size and of the untraceability notion, and LUAT is starvation-free. Partitioning the accounts into fixed masking sets lets exhausted sets be garbage-collected without increasing that number. In CUAT, a transfer consumes and replaces every account of its masking set, so two transfers whose sets intersect cannot both take effect. We formalize this with the conflict graph on masking sets, whose edges join sets sharing an account. Under weak untraceability, which protects a transaction in isolation, the consensus number is unbounded already for one-round protocols. Under strong untraceability, which protects against an observer of the complete history, untraceability holds on a history exactly when any two accounts sharing a masking set occur in the same number of the masking sets in it. This uniform incidence bounds the conflict graph, and matching constructions attain it, so the consensus number is determined exactly and grows quadratically in the masking-set size. Finally, CUAT is not starvation-free. The two objects therefore pay for the same
privacy differently: LUAT in storage, CUAT in synchronization and
fairness.
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All authors Christian Cachin, David Lehnherr, Juan Villacis, François-Xavier Wicht
Cryptography and Security
Which Model Is Actually Serving You? IRIS: Budgeted Black-Box Auditing of Model Substitution and Routing Dilution in LLM Gateways
Yuewei Zhang, Zhi-Hai Zhang and Hanzhang Qin
Commercial LLM gateways mediate access to hosted models, but the served backend may not match the advertised one: it may substitute a cheaper model on every request or route only a fraction $\epsilon$ of requests to it. Prior black-box auditors often need a privileged signal (log-probabilities,
token ranks, or reference samples) or a target-specific probe, fix the query budget in advance, and return a yes/no verdict. We present $\mathrm{IRIS}$, an audit that needs only the returned text: it asks endpoints to generate random numbers or strings, fingerprints the backend, and is the first to combine, in one text-only audit, detection of whole-stream substitution and fractional dilution, attribution of the served backend, routing-fraction ($\epsilon$) estimation, and a query budget it sizes itself. A cheap pilot fits the exponential query-error decay and freezes that budget before any suspect query is issued. On an intra-family Qwen3 ladder $\mathrm{IRIS}$ verifies the backend at $0.99$ AUROC and sharpens attribution as queries accumulate; across a commercial OpenRouter library it catches $\epsilon{=}0.3$ dilution on margin-qualified pairs at $0.85$ mean power ($0.017$ false-positive rate) and recovers $\epsilon$ to within $0.04$ for enrolled diluents; and a live cross-provider audit flags $14$ of $15$ same-model provider pairs by genuine quantization and kernel deviations, corroborated on third-party MET traces. Against comparable black-box auditors, $\mathrm{IRIS}$ matches or beats detection on shared tasks, and adaptive allocation lifts the matched-budget target-hit rate from $73$% to $87$%. Further experiments cover
adversarial gateways, knob identifiability, unseen diluents, and false-positive control.
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Cryptography and Security · Cross-listed from cs.LG
Beyond Heavy Log Curation: Perplexity-Based APT Detection via Unsupervised, Context-Augmented Language Models
Shoya Otsu, Kei Suzuki, Toshiaki Koike-Akino et al. (+2 more)
Advanced Persistent Threats (APTs) remain difficult to detect because only a small fraction of events in large-scale logs are attack-related, and investigation is expensive and hard to scale. Prior machine-learning approaches can reduce analyst workload, but they often rely on heavily curated training data and sophisticated preprocessing pipelines. Building and maintaining such pipelines require substantial domain expertise and engineering cost. Motivated by insights from a study of a strong APT detection baseline, we propose CAPTAIN (Context-Augmented Perplexity-based Threat Activity log detectIoN), a perplexity-based detector that leverages general, pre-trained
language models with minimal, domain-agnostic preprocessing, enabling robust scoring of long, minimally processed log entries. CAPTAIN encodes recent history with an encoder model and a Q-Former-style bridge, then injects the compact context
tokens into the decoder input so that perplexity reflects temporal context. To improve stability, CAPTAIN additionally applies smoothing filters to the perplexity time series. Across APT-oriented
benchmarks, CAPTAIN competes with strong existing baselines and remains robust under substantially less curated inputs, that reduces the development and operational cost of advanced log preprocessing.
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All authors Shoya Otsu, Kei Suzuki, Toshiaki Koike-Akino, Jing Liu, Ye Wang