Cryptography and Security
The Mirage of LLM Guardrails: A Case Study in AI-Assisted Medical Note Manipulation
Davis Yadav and Amulya Yadav
The rapid deployment of large
language models (LLMs) in healthcare settings makes the reliability of their built-in guardrails against malicious queries a question of urgent practical consequence. Yet the robustness of these mechanisms against deliberate misuse (in the healthcare context) remains poorly understood. In this paper, we investigate this question empirically, using AI-assisted medical note manipulation as a concrete case study. We make four novel contributions. First, we develop a reproducible manipulation pipeline that takes publicly available seed medical note templates and use commercial LLMs to produce customized manipulated notes by substituting patient names, provider identities, dates, and medical conditions across multiple model families, input formats, and
prompt phrasings. Second, we conduct a systematic empirical evaluation of LLM guardrail robustness for medical note manipulation. Our experimental results reveal substantial weaknesses and inconsistencies in contemporary commercial LLM guardrails, including low refusal rates for several model families. Third, we utilize a combination of automated metrics and human annotation-based metrics to assess the correctness of requested manipulations. Fourth, we conduct a user-study to assess the believability of manipulated medical notes, finding that the best manipulations are visually indistinguishable from original documents to human raters. Finally, we discuss implications for responsible guardrail design in LLMs, AI safety policies, and the broader ethics of deploying LLMs in healthcare settings.
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Cryptography and Security · Cross-listed from cs.LG
ADVERSARIAL: And-Inverter Graph-Assisted Hardware Trojan Detection At Scale
Yaroslav Popryho, Debjit Pal and Inna Partin-Vaisband
Modern System-on-Chip (SoCs) often contain hundreds of millions to tens of billions of gates, making existing Hardware Trojan (HT) detection methods impractical due to their immense scale. The proposed approach incorporates symbolically enabled learning by modeling flattened gate-level netlists as Boolean networks represented as And-Inverter Graphs (AIGs), where all internal nodes are 2-input AND gates and inversions reside on the edges. Each directed connection is expressed as a triple within a Knowledge Graph
Embedding (KGE) framework, producing compact, constant-size per-node representations that retain multi-hop structural context. The AIG's bounded fan-in and uniform semantics ensure training and inference complexity scale linearly with edge count, addressing major scalability bottlenecks in HT detection. Symbolically enabled learning across deep datapaths enables the model to differentiate
circuit structures from rare and functionally inconsistent connections that signify potential Trojan triggers and payloads. Experiments on large-scale SoC
benchmarks demonstrate clear
geometric separation between Trojan and benign nodes and practical scalability.
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Cryptography and Security
On a necessary condition for the matching cryptosystem stability
Aleksey Bolotnikov and Anwar Irmatov
The article contains a description of a possible attack on a matching cryptosystem and a defense with limited noise. A public key of a matching cryposystem consists of a graph and a weight vector-function on the edges of the graph with values from a finite field, where a private key contains another weight function, for which the corresponding alternating weighted path problem can be solved in
polynomial time. There is a specific family of these secret weight functions that is considered in this article, for which some of the coordinates of its vector values are described as limited noise. We suggest a necessary condition for the matching cryptosystem stability in terms of dimensions of spans of weight vectors that correspond to specific sets of edges of the graph from the public key.
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Cryptography and Security
TriShieldRAG: 3 Rings, One Blind Spot in Layered Defenses for Retrieval-Augmented Generation
Susil Kumar Mohanty, Rohit Patel, Kosuru Yuvaraj et al. (+2 more)
Retrieval-Augmented Generation (RAG) grounds LLM answers in query-time retrieved documents, so reliability depends on what the retriever returns. PoisonedRAG (Zou et al., USENIX Security'25) showed five crafted documents mislead an undefended system in nearly 90% of cases, and that single-stage defenses give limited robustness. We propose TriShieldRAG, a three-layered framework: an Ingest Guard for document-level screening, a
Retrieval Scorer for trust-aware re-ranking, and a Cross-LLM Consensus over three diverse models. We reasoned that collectively screening, re-ranking and validating retrieved evidence would give complementary protection, limiting the ability of poisoned documents to succeed through any single failure. We evaluate against non-adaptive and adaptive poisoning. Non-adaptively, on the full 2.68M-passage Natural Questions (NQ) corpus with the original PoisonedRAG attack, it cuts attack success from 79 +/- 1.0% to 1 +/- 0.0%. Adaptive attacks expose fundamental limits of layering. By changing only the document formatting, without modifying the poison text or accessing the retriever, the attacker reduces the Ingest Guard score from 0.500 to 0.000 and bypasses it on all 500 tested documents across three corpora. The remaining layers then give no protection: 62 +/- 0.8% attack success against a 56 +/- 2.5% undefended baseline on NQ, and 85 +/- 0.6% against 86 +/- 0.6% on HotpotQA. Layered defenses relying on the same retrieved evidence fail together: poisoned context misleads both re-ranking and consensus validation. Minority-poison thresholds prove corpus-dependent, at 0.214, 0.251 and 0.558 rather than the derived 0.5; a closed form we proposed for these failed a pre-registered prediction and is retracted. Cross-model agreement is misleading, reaching 0.96 while attack success approaches 99%. We release the framework, the evasion-certification methodology and artifacts.
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All authors Susil Kumar Mohanty, Rohit Patel, Kosuru Yuvaraj, Jeenal Chaudhary, Disha Singhania
Cryptography and Security
Bridging the Epistemic Gap in the Invisible Internet: Extended Mathematical Modeling and Empirical Characterization of I2P Topology
Siddique Abubakr Muntaka, Jacques Bou Abdo and Liaquat Hossain
The Invisible Internet Project (I2P) is a decentralized, peer-to-peer network underpinning secure and
adversarial communications with major implications for cybersecurity and national security. Its global
topology emerges from thousands of independent peer-selection decisions, producing a hub-dominated, complex structure that resists external observation. Prior models based on protocol documentation failed to capture real-world behavior. We close this gap with an Extended Mathematical Model (EMM) derived from production code and validated on a six-router, geographically distributed testbed over thirty days. Results reveal limited router visibility (~25% of nodes), relativistic tier allocations, strong Fast-tier tunnel preference, and overrepresented High Capacity-tier exploratory tunnels. The model accurately predicts emergent topological asymmetries and defines the
adversarial resources required to compromise
privacy, providing a principled foundation for cyber deterrence and secure decentralized network design.
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Cryptography and Security · Cross-listed from cs.DS
Bitcoin Mempool Linearization
Arman Mollakhani, Pieter Wuille and Dongning Guo
In the Bitcoin system, transactions arrive continuously at miners' mempools and await inclusion in future blocks. Every non-coinbase transaction must spend one or more unspent outputs created by previous transactions, inducing dependency constraints among transactions in the mempool. At the same time, miners are economically incentivized to prioritize transactions with higher fee rates, measured as transaction fee per unit size. This paper formulates the mempool linearization problem: given a set of transactions with associated fees, sizes, and dependency relationships, compute a dependency-respecting transaction ordering that maximizes fee-rate efficiency while supporting efficient updates as the mempool evolves dynamically. The problem is characterized through a partition of transactions into disjoint dependency-respecting subsets ordered by decreasing aggregate fee rate, together with an equivalent linear programming formulation. Motivated by structural properties of basic feasible solutions in the simplex method, a new
algorithm called spanning forest linearization (SFL) is developed. Operating directly on the transaction dependency graph, SFL iteratively merges and splits chunks of transactions to refine a global ordering, and is guaranteed to terminate at an optimal solution. Evaluation on both synthetic and real-world Bitcoin mempool data shows that SFL consistently computes optimal linearizations with substantially lower runtime than competing approaches, including a method based on the parametric preflow
algorithm of Gallo, Grigoriadis, and Tarjan. These results indicate that SFL provides a practical and scalable framework for transaction prioritization by decentralized miners in large and rapidly evolving mempools. SFL has also been incorporated into the Bitcoin Core codebase for transaction cluster linearization.
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Cryptography and Security
ZKP Security Tools and Verification: Coverage, Effectiveness, Adoption, and Challenges
Arman Kolozyan, Tom Sorger, Alexander Hicks et al. (+1 more)
Zero-knowledge proofs (ZKPs) have become a core technology for
privacy and verifiable computing. They are used to secure blockchains that handle billions of dollars and identity applications dealing with sensitive personal data. However, ZKP systems are complex, and subtle implementation errors can completely break their guarantees, letting attackers forge money or false proofs of identity. Researchers and practitioners have therefore developed a growing set of bug detection and formal verification methods to secure these systems. Yet their real-world effectiveness and adoption remain unclear. In this paper, we aim to shed light on the state of ZKP security tooling. We first systematize the landscape of these tools and observe that most target Circom, leaving newer DSLs and zkVMs with limited support. We then evaluate six tools across 70 real-world vulnerabilities and find that while the tools detect 45.7% of bugs on isolated targets, their effectiveness drops to 19.6% on full codebases, with important vulnerability classes left unaddressed. We also present the first systematic analysis of formal verification efforts, revealing that current work focuses primarily on constraint correctness and identifying key gaps and risks. Finally, we survey 48 practitioners, showing that development and security remain human-led, LLMs are widely used, and practitioners prioritize tools with clearer guarantees and lower integration effort. Overall, our results highlight the need for better integration of security tooling with the development and auditing process, and we provide actionable insights for researchers and practitioners.
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All authors Arman Kolozyan, Tom Sorger, Alexander Hicks, Stefanos Chaliasos
Cryptography and Security · Cross-listed from quant-ph
Can PCE solve the factorisation problem via optimisation?
Fernando Alonso, Colomán Samprón, Jacobo Veiga et al. (+1 more)
The ongoing progress in
quantum technologies has fueled a sustained exploration of their potential applications across various domains, particularly in computational problems that are considered intractable for classical systems. Among these problems, integer factorisation remains of special interest due to its relevance to widely used cryptographic schemes such as RSA. Among the different possibilities, one approach to factorisation is to convert the problem into a binary optimisation problem. However, current proposals usually need a large number of
qubits that make them unfeasible within the current hardware. In this work, we investigate a possible adaptation of the Pauli Correlation Encoding (PCE)
algorithm to the factorisation problem. Due to its compression capability, it can drastically reduce the number of needed
qubits. The proposed approach explores how the structure and dynamics of the PCE framework may be employed to encode and analyze candidate factor relations within a
quantum computational setting. Rather than presenting a replacement for established
quantum factorisation methods, this study aims to provide a preliminary examination of the feasibility and limitations of the proposed adaptation. We discuss the algorithmic design, its conceptual relationship with existing
quantum approaches, and the practical constraints associated with implementation on current or near-term
quantum hardware. Initial observations suggest that the method may offer an alternative perspective for studying factorisation within the broader context of
quantum computation, although no claim is made regarding computational advantage. These results are intended primarily as an exploratory contribution to ongoing research in
quantum algorithms and computational number theory.
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All authors Fernando Alonso, Colomán Samprón, Jacobo Veiga, Andrés Gómez
Cryptography and Security
The Illusion of Secure LLM Code: Closing the Security Gap via Iterative Reprompting
Ishpuneet Singh, Shreyas Mahajan, Gurjot Singh et al. (+1 more)
Large
Language Models (LLMs) are increasingly integrated into software development workflows, yet their ability to autonomously generate secure authentication code remains uncertain. This paper evaluates the security architecture of authentication systems generated by five prominent AI coding assistants through a bi-modal assessment framework combining static code analysis and dynamic penetration testing, mapped to NIST SP 800-63B guidelines. The study examines model behavior across four prompting strategies Basic, Secure, NIST-Based, and Reprompting to reflect varying levels of developer guidance. Empirical results demonstrate that code generated from functional or generically secure
prompts consistently omits critical protections, particularly concerning brute-force resistance, session management, and robust password handling. While providing explicit, single-shot NIST context significantly improves compliance, the findings reveal that this remains structurally inadequate. Instead, iterative Reprompting: forcing models into a contextual self-auditing loop is strictly required to achieve a comprehensive, defense-in-depth security architecture. Ultimately, this study proves that current AI coding assistants do not produce secure-by-default applications, dictating that enterprise deployments must transition from single-shot
prompt engineering to continuous, standards-driven verification pipelines.
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All authors Ishpuneet Singh, Shreyas Mahajan, Gurjot Singh, Maninder Singh
Cryptography and Security
SMARM+: Analyzing and Enhancing Shuffled Measurements for Remote Attestation in Real-Time IoT Settings
Amarin Laohajirapan and Norrathep Rattanavipanon
Remote attestation (RA) is a lightweight security primitive for detecting software compromise on IoT devices. Traditional RA schemes require atomic, non-interruptible
memory measurements, making them difficult to deploy alongside real-time workloads. SMARM addresses this limitation by measuring
memory in a secret, shuffled block order, reducing the non-interruptibility period to the duration of a single block measurement. However, SMARM was originally designed for microkernel-based systems and has not been studied in RTOS-driven real-time environments. In this work, we present the first systematic study of SMARM in real-time RTOS-based setups. We implement SMARM on commodity ARM TrustZone-M hardware running FreeRTOS and Zephyr, and introduce the Frequency Accuracy Ratio (FAR) to quantify the extent to which attestation can coexist with real-time execution under varying workloads. Our evaluation shows that SMARM's real-time compatibility is highly sensitive to block size: large blocks significantly degrade real-time availability, while small blocks incur substantial secure-storage overhead, limiting deployability on
memory-constrained devices. To address this limitation, we propose SMARM+, a family of enhanced SMARM variants consisting of SMARM+PRNG and SMARM+FPE. They are designed to reduce secure-storage requirements while preserving SMARM's security guarantees and real-time behavior. Our evaluation highlights the trade-off between secure-storage reduction, attestation runtime, and energy overhead, and provides guidance on selecting among SMARM, SMARM+PRNG, and SMARM+FPE for different deployment settings.
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Cryptography and Security
DualityCert: Verifier-Gated Language-Model Repair of Broken Duality Claims in Quantum Field Theory
Xingyang Yu
We present DualityCert, a symbolic verifier for candidate Seiberg-duality claims in four-dimensional N=1 quiver gauge theories. The verifier evaluates 't Hooft anomaly matching, superpotential R-charge consistency, central-charge matching, and a bounded chiral-ring proxy. A claim that passes receives a consistency certificate, which states that no tested inconsistency was found, not that the duality is proven. We use the verifier as a repair environment for
language-model
agents, which receive a deliberately broken claim and must edit it until it certifies. On a preregistered
benchmark of 145 broken claims, with the analysis fixed before the first confirmatory model call, verifier-gated retry improves final repair success over a single attempt by +8.3 percentage points (pp) on deepseek-chat and +7.1 pp on qwen-plus (Holm-adjusted p<0.002). Under an equal budget of eleven attempts, the stop-first strategy portfolio underperforms independent verifier-filtered resampling by 10.3 percentage points on deepseek-chat but outperforms it by 14.7 points on qwen-plus, reversing the ordering of the two tested verifier-exploitation policies across the two confirmatory models. On qwen-plus, category-level verifier feedback is worth +8.7 pp over content-free retry, and interpretable obligation identities alone are worth +6.4 pp over structurally identical masked feedback. Neither effect is detected on deepseek-chat. Separately, a preregistered MiniMax-M2.5 extension again finds an iteration gain and independent verifier-filtered resampling outperforming the strategy portfolio. Which policy is better thus differs between the two models, while every winning policy uses the same cheap certificate. The verifier,
benchmark, protocol, and all per-attempt records are released.
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Cryptography and Security
HiTMS: A High-Throughput Multi-Stream Linguistic Steganography Framework
Ruiyi Yan, Zhongliang Yang and Yugo Murawaki
Generative linguistic steganography conceals secret bits within the sampling randomness of large
language models. Existing schemes are single-stream, conveying an entire secret through a single response to a single
prompt. This convention incurs limitations: it provides no protocol-level support for batched multi-stream inference, and naive co-batching does not conceal slot occupancy or payload completion. We propose the High-Throughput Multi-Stream (HiTMS) framework, which distributes a secret across multiple responses produced jointly over successive rounds of interaction. Each round embeds and extracts several streams within a single batched call, thereby amortizing the cost of model invocation and substantially improving throughput. To ensure recoverability, HiTMS wraps each response in a self-describing frame and employs a key-derived schedule that binds streams to slots and fills unused slots with decoys, guaranteeing exact recovery while concealing the number of active streams. The framework is agnostic to both the
language model and the steganographic coder. Across eight
dataset-model-coder settings, eight-stream HiTMS achieves up to 4.3 times higher
embedding and extraction speeds than single-stream baselines, while reducing the average area under the receiver operating characteristic curve (AUROC) of steganalyzers from 0.681 to 0.601. Experiments with 4 to 64 streams demonstrate sustained throughput gains as concurrency increases. GitHub repository for this work is https://github.com/ryehr/HiTMS_steganography.
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Cryptography and Security · Cross-listed from cs.AI
Are You Still the Agent I Authorized? Earned Authority under a Fixed Ceiling for Evolving Agents
Zhaoxi Zhang and Xiaomei Zhang
Long-lived AI
agents increasingly evolve after deployment by retaining experience, acquiring skills and tools, revising workflows, delegating work, and moving across task phases. This improves adaptation but creates a distinct authorization problem. Tool-enabled
agents can turn model errors and
prompt injections into consequential external actions; when
evolution occurs under a live grant, the subject exercising that authority or the context in which it acts may no longer match what the user evaluated.
Evolution can change both the effects reachable under an old grant and the authority required by the task, which may rise, fall, or become incomparable. Existing tool policies constrain actions but do not determine when a grant survives this change. We formulate authorization continuity: when does an existing grant remain valid, how may active authority change, and what boundary must never move? Our state-bound model fixes a transition envelope and an immutable effect ceiling at grant time. The envelope determines whether the grant survives a mutation; below the ceiling, authority may contract freely and expand only under specified evidence conditions. We distinguish requested from realized effects and prove that, under complete mediation, sound effect abstraction, attenuating delegation, and monitor integrity, mutation cannot amplify protected effects beyond the user-issued ceiling.
Agent-produced evidence may allocate authority below the ceiling but cannot raise it. Finally, we map six mutation classes to their authorization consequences.
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Cryptography and Security
Screen-Conditioned Watermarking Against Multi-Screen Collusion Attacks
Mingyue Chen, Xin Liao, Yufeng Wu et al. (+2 more)
Screen-shooting poses a significant threat to confidential information protection. While existing screen-shooting watermarking methods enable copyright verification, the copyrighted images carrying the same copyright watermark across different screens often exhibit highly similar and estimable watermark patterns. These shared patterns can be exploited for watermark removal and forgery, a threat we term the multi-screen collusion attack. To mitigate this threat, we propose CoMSMark, a collusion-resistant image-agnostic watermarking framework for multi-screen shooting, which reduces shared residual components across screens to resist multi-screen collusion attacks. Specifically, we incorporate screen ID through a style modulation mechanism, enabling the encoder to generate screen-specific watermark residuals for reliable source attribution. We further introduce a collusion suppression loss that reduces shared residual components and encourages high-
entropy predictions for forged samples, improving resistance to collusion attacks. Finally, to enable efficient large-scale distribution, CoMSMark employs an image-agnostic encoding paradigm that generates watermark residuals independently of image content. Extensive experiments demonstrate that CoMSMark effectively resists both collusion-based watermark removal and forgery. It maintains an average watermark accuracy above 90% under removal attacks while keeping forged-watermark accuracy near 50%. Moreover, CoMSMark achieves competitive robustness under diverse screen-shooting conditions, including varying capture distances and angles.
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All authors Mingyue Chen, Xin Liao, Yufeng Wu, Han Fang, Xiaoshuai Wu
Cryptography and Security
Mission-Level Runtime Assurance for LLM-Assisted ISR Swarms over a Verification-Aware Fabric
Nikolaos Kekatos, Michael Ioannou, Panagiotis Katsaros et al. (+4 more)
Swarms of LLM-assisted autonomous
robots are increasingly proposed for cooperative intelligence, surveillance, and reconnaissance (ISR) in contested environments. A growing class of their assurance failures arises not within any single platform but across the swarm: individually-compliant actions compose into a mission-level violation: a prohibited objective split across platforms to evade per-platform limits, or a collective budget quietly exceeded. Per-platform guardrails miss these by construction, and contested communications let the violation hide behind lost or delayed evidence. We present a three-tier (platform/squad/mission) compositional runtime-verification framework that decomposes a mission policy into per-
agent and cross-
agent aspects, aggregates per-platform verdicts over a verification-aware messaging fabric, and fuses them with an evidence-aware, two-axis (security x completeness)
algebra whose provenance names the platforms that jointly triggered a violation. Because the fabric makes evidence loss and silence observable, unsupported negative verdicts are downgraded to an explicit unknown rather than reported as mission-wide all-clears. On a simulated ISR mission, an indirect
prompt injection that causes real LLM planners to split a prohibited collection task across four platforms is invisible to every per-platform monitor yet detected compositionally with full provenance; under an injected fault campaign a best-effort central monitor emits silent false all-clears while the verification-aware fabric emits none.
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All authors Nikolaos Kekatos, Michael Ioannou, Panagiotis Katsaros, Alexios Lekidis, Theodoros Nestoridis, Tom Nianios, Dimitrios Nikou
Cryptography and Security · Cross-listed from cs.AI
Do LLMs Know Their Vulnerable Scenarios?
Ziheng Peng, Huiqi Deng, Haoran Jing et al. (+5 more)
Safety-aligned large
language models are trained to refuse harmful requests, yet
embedding the same requests in particular scenarios can bypass their safeguards. Existing red-teaming methods empirically identify effective scenarios through observed attack outcomes, but why particular scenarios weaken refusal remains mechanistically unclear. Meanwhile, mechanistic interpretability studies have characterized both refusal directions and jailbreak-associated features, without explaining the relationship between the two representations. In this work, we show that scenario-wrapped
prompts activate internal scenario directions whose causal steering consistently reduces refusal scores. Building on this finding, we propose Concept2Scenario, a concept-based attribution framework for vulnerable scenario discovery. It instantiates a broad concept space with a sparse autoencoder, attributes refusal suppression to individual concepts, translates the identified concepts into interpretable natural-
language scenarios, and identifies synergistic scenario combinations through interaction attribution. Across three open-source models, two safety
benchmarks, and six black-box jailbreak methods, the discovered scenarios serve as reusable priors that improve average attack success rates by up to $18.2$ percentage points. They also transfer to GPT-5, Claude-Haiku-4.5, and Gemini-3-Flash, suggesting that some scenario-level refusal vulnerabilities are shared across model families. Moreover, the identified combinations outperform their individual constituents and enable iterative attacks to succeed in fewer turns.
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All authors Ziheng Peng, Huiqi Deng, Haoran Jing, Xuankun Rong, Jiahui Han, Xiting Wang, Na Zou, Xia Hu
Cryptography and Security
ATLAS: Automated Approximation of Transformers for Efficient Homomorphic Inference in One Hour
Jianhang Xie, Sicheng Tan, Vishnu Naresh Boddeti et al. (+1 more)
Fully homomorphic encryption (FHE) lets a server run inference on encrypted data with strong
privacy guarantees, but running a
Transformer under FHE is expensive. Its non-linear operations, such as softmax, normalization, and activation, must be replaced with
polynomial approximations that the CKKS scheme supports, and the depth of these approximations dominates inference cost. Existing FHE
Transformers use hand-tuned approximation settings, such as iteration count and
polynomial degree, applied uniformly across layers, models, and tasks. Hand-tuning is slow and error-prone. Even a single uniform setting has about $10^7$ choices, and manual search cannot exploit layer-wise variation. AutoFHE, the only automated method with multi-objective search, targets ReLU-only CNNs and needs full fine-tuning per candidate, which is too costly for
Transformers. Per-layer settings also push the search space to about $10^{85}$ for BERT and ViT and $10^{228}$ for LLaMA3, beyond both manual and fine-tuning-based search. We present ATLAS, a training-free framework that automates this search by treating each layer's approximation setting as a multi-objective optimization over latency and accuracy. The problem is hard: the decision space is large (96 or 256 variables), each configuration takes 70 to 1,000 seconds to evaluate even in cleartext, and 85 to 90 percent of configurations are invalid. ATLAS handles this with a two-stage optimization strategy and a surrogate model, completing the search in about one hour. Compared to an iterative softmax baseline, ATLAS cuts multiplicative depth and end-to-end latency by about 35 percent with little accuracy loss, and works across encoder-only, decoder-only, and
vision Transformers, complementing parallel work on packing and
matrix multiplication.
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All authors Jianhang Xie, Sicheng Tan, Vishnu Naresh Boddeti, Zhichao Lu
Cryptography and Security
Isolated but Exposed: Persistence-Based Memory Extraction Attack on LLM Agents
Xinyu Gao, Wenyu Chen, Xiangtao Meng et al. (+5 more)
LLM-based
agents extend large
language models with long-term
memory (LTM) that persists
privacy-sensitive user data across sessions. Production systems mitigate extraction risks through
memory isolation, binding each user's LTM to a unique identifier. This defense has blocked known attacks on shared storage, fostering the assumption that isolated LTM is secure. We identify the tool interface as an overlooked attack surface.
Agents routinely embed LTM-retrieved data in tool invocation parameters, enabling a malicious tool to exfiltrate private
memory without violating user-level isolation. Naive adaptations of user-side extraction techniques fail because the
adversarial command's semantics interfere with
retrieval precision, and platform-imposed tool-call limits constrain the extraction budget per trigger. We present SPORE, the first extraction attack designed for this threat model. SPORE decouples the
adversarial command from
retrieval anchors by persisting the command in short-term
memory and emitting semantically pure anchors in tool responses. The restored
retrieval precision enables a
geometric coverage optimization over the
embedding space that systematically steers anchors toward unexplored
memory regions. To sustain extraction beyond tool-call limits, SPORE persists reactivation payloads in
memory that automatically resume the attack within and across sessions without additional user triggers. SPORE achieves an 80.0% record extraction rate with unlimited triggers and 47.0% with only 20 triggers. In multi-user deployments, attackers can link extracted records to user identities, enabling targeted surveillance. These results demonstrate that
memory isolation alone is insufficient and call for reexamining tool-side trust boundaries in
agent architectures.
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All authors Xinyu Gao, Wenyu Chen, Xiangtao Meng, Li Wang, Chuanchao Zang, Jianing Wang, Zheng Li, Shanqing Guo
Cryptography and Security
Renting the Cracking Machine with a Cost-and-Time Analysis of Exhaustive DES-56 Key Search in the Cloud
Gonzalo Sharif Curi Martínez and Rodrigo Ramele
The Data Encryption Standard (DES), with its 56-bit key, has been considered cryptographically broken since 1998. However, a concrete, reproducible measurement of the cost and time required to perform an exhaustive key search using today's commodity cloud infrastructure has not been widely reported in recent literature. In this paper we present a distributed brute-force system built on AWS EC2 that partitions the $2^{56}$ keyspace across 37 c6i.2xlarge instances running a C/OpenMP worker, achieving a measured throughput of $2.91$\,M\,keys/s per instance (${\sim}108 \times 10^6$ keys/s aggregate). We conduct 15 independent trials covering keyspace offsets from $10^6$ to $1.5 \times 10^{10}$ keys, measuring wall-clock time and monetary cost per trial. For small offsets ($\leq 10^8$), total time is dominated by AWS instance boot latency (${\approx}\;90$\,s), yielding a mean of $116.8\pm20.1$\,s at \$0.41 per attack. For larger offsets the search time dominates and grows linearly: a key at offset $1.5{\times}10^{10}$ requires ~${\approx} \; 87$ minutes and \$18. At the measured aggregate throughput of 108\,M\,keys/s, exhausting the full $2^{56}$ keyspace with these 37 instances would take ${\approx} \; 21$ years; however, because the workload is embarrassingly parallel and cloud capacity is elastic, the same search can be traded for money almost linearly. Extrapolating our measured cost, a complete exhaustive search would cost ${\approx} \; \$1.2$M and, with a sufficiently large fleet, could be completed in about one day. The system is thus practical for bounded-subspace attacks at negligible cost, and full DES exhaustion, while expensive, is firmly within reach of a well-funded attacker using only commodity cloud resources.
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Cryptography and Security
PATCH-FFT: Unmasking Dormant Hardware Trojans with Patch-Based Frequency-Domain Transformers
Hasala Senevirathne and Amin Rezaei
Hardware Trojans embedded by malicious entities in integrated
circuits can covertly leak sensitive information through power side channels, often remaining undetected in their dormant state until specific trigger conditions activate their malicious behavior. For information-leaking Trojans, detection in the dormant state is critical, as once triggered, the secret data is already exfiltrated. This paper introduces a patch-based
Transformer architecture for detecting dormant hardware Trojans through frequency-domain analysis of power traces. Our approach converts time-domain power measurements into frequency-domain representations using real Fast
Fourier Transform (rFFT), revealing spectral signatures hidden in conventional time-series analysis. Experimental results demonstrate that our method achieves 90.94% average detection accuracy across dormant and active Trojan scenarios, outperforming state-of-the-art approaches particularly in detecting dormant Trojans that prior time-domain methods do not address.
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Cryptography and Security
TroPUF: Evaluating Hardware Trojan Insertion in Delay-Based Physical Unclonable Functions
Marissa Marcarelli and Amin Rezaei
Delay-based Physical Unclonable Functions (PUFs) are commonly used for device authentication and key generation due to the fact that they rely on manufacturing induced delay variations. However, these same variations make PUFs inherently non-deterministic, which can allow malicious logic to blend in with normal
circuit behavior. As a result, the act of
embedding hardware Trojans directly inside the PUF primitive presents a unique security risk that is not yet well understood. This work presents a unified simulation framework for evaluating stealthy hardware Trojan insertion across multiple delay-based PUF architectures and Trojan types. Functional metrics, hardware overhead, and resistance to machine learning modeling are assessed in parallel. Results show that dormant Trojans preserve expected PUF behavior, structural characteristics, and modeling resistance. Detectable degradation appears only after activation, indicating that conventional validation techniques fail to identify embedded Trojans prior to payload execution. These findings expose a gap in current PUF security assumptions, and highlight the need to evaluate PUFs and hardware Trojans as a coupled security problem.
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Cryptography and Security
Early Detection of Hardware Trojans Using Neural Controlled Differential Equations and Analysis of Power Traces
Hasala Senevirathne, Rahul Vishwakarma and Amin Rezaei
Evolving Hardware Trojans pose a serious threat to modern digital systems by evading traditional detection through stealthy, adaptive behavior. Even recent methods that leverage advances in machine learning can only detect them after activation, leaving a critical window for potential security breaches. To address this gap, we propose a novel approach for hardware Trojan detection and prediction using Neural Controlled Differential Equations (NCDEs) and analysis of power traces. Our method leverages an NCDE model trained exclusively on Trojan-free data to learn nominal power behavior, combined with a Linear Discriminant Analysis (LDA) classifier calibrated on labeled data, to distinguish between three scenarios: no Trojan, dormant Trojan, and active Trojan. Our method uses a sliding window to process side-channel measurements, enabling detection of subtle power consumption deviations that indicate Trojan presence, even when dormant. Experimental results demonstrate that the proposed NCDE-based method achieves superior accuracy compared to traditional machine learning approaches, with the additional advantage of handling dormant Trojans above a sensitivity threshold. We validate our approach on standard hardware Trojan
benchmarks, showing robust detection and prediction performance.
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