Cryptography and Security
Multimodal User Authentication Method via Fusion of Keystroke Dynamics and Glove-Based Hand Kinematics
Issei Hyakuda and Lei Jing
Although keystroke dynamics are cost-effective behavioral biometrics, their practical deployment is hindered by susceptibility to environmental variations. To address this, we propose a robust
multimodal authentication framework that augments traditional keystroke dynamics using 19-dimensional hand kinematics. Features are captured using a bespoke data glove equipped with 10 piezoresistive pressure sensors and a 9-axis IMU. A hybrid CNN-LSTM architecture effectively fuses these heterogeneous time-series streams. To ensure real-world applicability, we implemented a rigorous "unseen" evaluation protocol: the model was trained on a desktop keyboard using data from 1 target user and 8 "known" impostors, but evaluated on a laptop keyboard (cross-domain) against the target and an "unknown" impostor excluded from training. Averaged over five trials, the
multimodal method achieved a mean Equal Error Rate (EER) of 2.12% for individual 600-ms authentication events (Window 1). Crucially, aggregating scores over 10 events (6 seconds) using a temporal smoothing window yielded perfect authentication (0.00% EER). While our ablation study showed IMU kinematics alone achieved equivalent performance in a static laboratory, error analysis confirmed that pressure and IMU sensors, despite strong physical correlation, possess distinct sensitivities to error factors. Fusing these modalities establishes a vital fail-safe against real-world vulnerabilities like spatial spoofing and environmental noise, highlighting that combined physical traits provide much stronger biometric discrimination than timing features alone.
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Cryptography and Security
A Survey on Security with Quantum Computing
Manik Kumar Sangala, Robin Naira, Akhirul Islam et al. (+2 more)
Quantum computing has emerged as a transformative computing paradigm capable of solving problems that remain computationally infeasible for classical systems; however, its rapid advancement also introduces significant security,
privacy, and reliability concerns. In this context, this survey presents a comprehensive review of security challenges and mitigation strategies associated with
quantum computing, focusing on security issues in
quantum computers, security threats caused by
quantum computers, and security mechanisms developed for
quantum systems. The paper examines vulnerabilities in
quantum hardware and software, the impact of
quantum computing on existing cryptographic infrastructures and cybersecurity mechanisms, and the development of
quantum-resilient solutions such as post-
quantum cryptography,
quantum-safe communication protocols,
quantum intrusion detection systems, and
quantum-aware software engineering techniques. In addition, the survey discusses emerging applications of
quantum technologies in cybersecurity domains, including malware detection, network intrusion detection, Internet of Things (IoT) security, and secure communication systems. Furthermore, the paper analyzes existing
quantum error mitigation and fault-tolerance approaches designed to improve the robustness and trustworthiness of
quantum computation under realistic noisy conditions. By consolidating recent advances, open research challenges, and future directions, this survey provides a structured overview of the evolving intersection between
quantum computing and cybersecurity, while serving as a reference for researchers and practitioners working toward secure, resilient, and
quantum-ready computing infrastructures.
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All authors Manik Kumar Sangala, Robin Naira, Akhirul Islam, Sudip Biswas, Manojit Ghose
Cryptography and Security
Detecting Data Exfiltration through I2P Anonymity Networks: A Two-Phase Machine Learning Approach
Siddique Abubakr Muntaka, Muntaka Mohammed, Mansuru Mikail Azindo et al. (+9 more)
The Invisible Internet Project (I2P) provides strong anonymity through garlic routing and distributed network architecture, making it attractive for legitimate
privacy needs. Nevertheless, the same properties can be exploited by malicious actors to steal sensitive information from corporate networks without detection. Current network security measures often fail to detect I2P traffic, and existing literature has focused primarily on protocol-level traffic identification without addressing behavioral threat assessment. This paper proposes a two-stage machine-learning model for I2P traffic analysis using the SafeSurf Darknet 2025
dataset comprising 184,548 network flows. Phase 1 achieved 99.96% accuracy in distinguishing I2P traffic from normal network traffic using a Random Forest classifier, with only 2 false positives among 32,318 normal flows. Phase 2 performed behavioral analysis on traffic identified as I2P, classifying it as either exfiltration or legitimate activity, achieving 91.11% accuracy using XGBoost. The system demonstrates that tree-based ensemble methods substantially outperform deep neural networks and support vector machines for this task. Feature importance analysis indicates that the most discriminative features are packet timing and flow duration. These findings establish that accurate I2P traffic detection and threat prioritization are achievable in operational network environments, enabling security teams to focus resources on high-risk events rather than monitoring all encrypted traffic.
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All authors Siddique Abubakr Muntaka, Muntaka Mohammed, Mansuru Mikail Azindo, Ibrahim Tanko, Franco Osei-Wusu, Edward Danso Ansong, Benjamin Yankson, Oliver Kornyo, Foster Yeboah, Jones Yeboah, Richmond Adams, Pulcheria Serwaa
Cryptography and Security · Cross-listed from cs.LG
An exponential mechanism based on quadratic approximations for fine-tuning machine learning models with privacy guarantees
Hoang Tran, Jorge Ramirez, Jiayi Wang et al. (+3 more)
Fine-tuning adapts a pretrained machine learning model to a small, sensitive
dataset, but this process risks memorizing individual new data points, making the model vulnerable to adversaries who seek to extract sensitive information. In this work, we develop a randomized
algorithm based on the exponential mechanism for fine-tuning while ensuring differential
privacy. Our key idea is to construct a simple utility function that combines a local quadratic approximation of the pretrained model with information from the new
dataset. The resulting exponential mechanism admits exact sampling from a multivariate normal distribution in closed form. We establish theoretical
privacy guarantees, sensitivity bounds, and accuracy estimations for our method. We further introduce a random-projection strategy that makes the approach scalable to high-dimensional models. Numerical experiments on the MNIST
benchmark and the MIMIC clinical
dataset demonstrate competitive performance against existing differentially private fine-tuning techniques.
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All authors Hoang Tran, Jorge Ramirez, Jiayi Wang, Alberto Bocchinfuso, Christopher Stanley, M. Paul Laiu
Cryptography and Security · Cross-listed from cs.LG
SMA-DP: Spectral Memory-Aware Differential Privacy for Deep Learning
Mohammad Partohaghighi and Roummel Marcia
Differentially private
stochastic gradient descent (DP-SGD) enables private deep learning through per-example clipping and calibrated Gaussian noise, but its high-variance updates can reduce utility on challenging
datasets. We propose SMA-DP-SGD, a Spectral
Memory-Aware Differentially Private
Stochastic Gradient Descent method that augments DP-SGD with a fractional
memory branch built only from previously privatized noisy releases. WeightWatcher-inspired power-law spectral exponents provide group-wise reliability signals, instantiated layer-wise in our experiments, to adapt the decay and effective
memory depth. Private-history
alignment, norm matching, and warm-up activation stabilize the
memory contribution.
Privacy remains transparent: conditioned on the private release history, the
memory branch is fixed, and the only newly data-dependent term is the current clipped sum scaled by a fixed coefficient \(\beta\). Hence, SMA-DP-SGD preserves a clean conditional sensitivity structure and exactly recovers group-wise DP-SGD when \(\beta=1\). Experiments on CIFAR-100, CIFAR-10, and MNIST show competitive or superior accuracy over several DP optimization baselines, with the largest gains on CIFAR-100 and CIFAR-10. CIFAR-10 ablations show that \(\beta\) controls the
privacy–utility trajectory, while spectral and
memory diagnostics confirm a controlled short-to-moderate effective
memory depth and a small
memory-branch ratio. Runtime analysis shows that the mechanism incurs additional overhead, about \(2.94\times\) DP-SGD in our CIFAR-10 implementation, revealing a practical trade-off between adaptive private
memory and computational cost.
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Cryptography and Security
Latent Geometry as a Structural Monitor: Eigenspace Alignment for Anomaly Detection in Anonymity Networks
Vaibhav Chhabra
Traditional anomaly detection marks events when measured signals cross predefined thresholds. This captures the moment of transition but not the structural pressure that precedes it. We propose treating large behavioral populations as
geometric energy landscapes whose deformation can be measured before and during major transitions. The central thesis is that structure precedes geometry: the structural organization of the population is the signal, and
geometric metrics are instruments for measuring it. Applied to the Tor anonymity network across 67 consecutive daily observation windows, the dual-observer pipeline identifies a stable nine-dimensional load-bearing subspace invariant across the observation period and validates this structure by Monte Carlo simulation at 16.8 sigma above the noise floor. Primary detection gates achieve 0.0% false positive rate on 24 confirmed stable windows. Forensic analysis of the February 20, 2026 confirmed infrastructure event formally falsifies the relay-departure hypothesis, identifying connectivity degradation without
topology change as a detectable network failure mode. The result is a candidate structural-monitoring framework for behavioral populations with sufficient telemetry.
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Cryptography and Security
Security Document Classification with a Fine-Tuned Local Large Language Model: Benchmark Data and an Open-Source System
Ivan Dobrovolskyi
Organizations that scan documents for sensitive information face a practical problem. Cloud services require data to be sent to external infrastructure, while rule-based tools often miss threats that depend on context. This study presents TorchSight, an open-source local system for security document classification built around a fine-tuned Qwen 3.5 27B model. The model was trained on 78,358 samples from 13 permissively licensed sources and GPT-4 synthetic data covering seven security categories and 51 subcategories. In the main evaluation on 1,000 documents, the model reached 95.0% category-level accuracy (95% confidence interval: 93.5-96.2). The tested commercial models scored 75.4-79.9% under the same prompting protocol. On a separate external set of 500 held-out samples, the model reached 93.8% accuracy, which suggests that performance extends beyond the main
benchmark, although the margin depends on
dataset composition and difficult boundary cases. The results show that a fine-tuned local model can support accurate security document classification while keeping document processing under local control.
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Cryptography and Security
Refusal Evaluation in Coding LLMs and Code Agents: A Systematic Review of Thirteen Malicious-Code Prompt Corpora (2023-2025)
Richard J. Young and Gregory D. Moody
The evaluation of large
language model refusal on malicious-coding tasks now spans at least thirteen publicly released
prompt corpora (AdvBench, the CyberSecEval family, RMCBench, RedCode, MCGMark, JailbreakBench, CySecBench, MalwareBench, CIRCLE, MOCHA, ASTRA, Scam2
Prompt / Innoc2Scam-bench, and JAWS-Bench), each constructed under a different protocol, released under different licensing terms, and validated (or not) against different inter-rater reliability standards. Existing surveys treat code security, jailbreak taxonomy, or vulnerability detection as the central object and mention these corpora only in passing. This paper reverses that framing: it treats the
prompt datasets themselves as the unit of analysis. Following a PRISMA-style protocol, we specify a search strategy, screen the recent literature on coding-LLM refusal evaluation, apply a uniform extraction template to each in-scope corpus, and synthesize the resulting catalogue along construction methodology,
prompt-construction taxonomy (modality, turn structure, elicitation style), reproducibility and licensing, and malware-category coverage. The synthesis surfaces three recurring methodological gaps: the absence of human-annotator baselines against which LLM-judge labels can be calibrated, the absence of cross-corpus comparability with refusal-rate statistics measuring non-equivalent constructs, and the fragmentation of malware-category taxonomies, with no canonical schema spanning the thirteen in-scope corpora. The review concludes with proposed methodological directions for next-generation corpora, including pre-registration of inclusion criteria, vendor-diverse multi-judge validation, Fleiss' kappa with bootstrap CI as the reliability baseline, and a candidate canonical taxonomy.
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Cryptography and Security · Cross-listed from cs.LG
Causal Unlearning in Collaborative Optimization: Exact and Approximate Influence Reversal under Adversarial Contributions
Ali Mahdavi, Azadeh Zamanifar, Amirfarhad Farhadi et al. (+1 more)
Federated learning systems must support data deletion requests to comply with
privacy regulations, yet retraining from scratch after each deletion is computationally prohibitive. We present HF-KCU, a method that removes a client's contribution by approximating the influence function through conjugate gradient iterations in Krylov subspaces, reducing complexity from O(d^3) to O(kd) where k<<d.A causal weighting mechanism ensures that only clients holding the deleted data receive parameter updates, preventing spurious changes to unaffected clients. Our method is designed to handle bounded
adversarial perturbations to the Hessian and gradient, providing graceful degradation under realistic threat models. We validate HF-KCU across convolutional (ResNet-18, SimpleCNN) and
transformer (ViT-Lite) architectures on CIFAR-10, MNIST, and Fashion-MNIST. On CIFAR-10 under Dirichlet (alpha=0.5) partitioning, HF-KCU achieves 47.75 times speedup over retraining while maintaining test accuracy within 0.60% of the rational baseline(71.16 vs 71.76 %). Membership inference attacks on the forget set yield success rates of 0.499 matching the retrained model and confirming effective
privacy restoration. We provide convergence guarantees showing that the Krylov approximation error decreases as O((k ^1/2-1)/(k^1/2+1)) where k is the Hessian condition number. The causal weighting mechanism ensures
surgical updates, where only clients holding deleted data are modified, preserving model quality for unaffected participants and avoiding the instability of gradient-based approaches in asynchronous
federated settings. This design provides interpretability as each update is directly traceable to the influence of the deleted data. The method's efficiency and precision make it suitable for production
federated systems where deletion requests arrive asynchronously and computational budgets are constrained.
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All authors Ali Mahdavi, Azadeh Zamanifar, Amirfarhad Farhadi, Omid Kashefi
Cryptography and Security
Pramana: A Protocol-Layer Treatment of Claim Verification in Autonomous Agent Networks
Ravi Kiran Kadaboina
Autonomous
agents deployed in regulated domains must produce a verification artifact per consequential output: a record an auditor can re-execute offline, capturing what was claimed, against what source, by whom, when, and how. Production verification today splits into two unstandardized halves. Probabilistic verdict patterns (self-consistency voting, reviewer LLM ensembles) produce judgments, not artifacts. Artifact-producing patterns (RAG, tool-augmented traces, generator-verifier loops) produce vendor-specific records no external auditor can reconstruct without bespoke integration. Pramana defines the missing wire format. Every consequential
agent output is wrapped in a typed ClaimAttestation with one of four variants (measurement, inference, analogy, citation), each paired with a verify() operation against the recorded source. verify() is deterministic for MeasurementClaim and CitationClaim. For InferenceClaim and AnalogyClaim, determinism is conditional on the oracle (audit-replayable when LLM-backed). The four-way typology derives from classical Indian epistemology (pramana, valid means of knowledge). The lifecycle is specified in TLA+ and exhaustively verified under TLC across three
symmetry-reduced models: 38,563 distinct reachable states, zero invariant violations. The Python reference implementation passes 84 tests. An A2A and MCP wire-extension manifest layers three deployment-grade invariants: reachability, SLA bound, and offline re-verifiability. An exploratory pilot (n=100, 2,275 reviewer calls) probes LLM-as-judge in code generation. The strongest observation is a 40-percentage-point raw FPR delta across corpora, consistent with reference-solution quality contributing significantly. The pilot does not validate Pramana on its own; the structural argument and formal verification do that.
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Cryptography and Security
Adaptive Probe-based Steering for Robust LLM Jailbreaking
Junxi Chen, Junhao Dong and Xiaohua Xie
Recent work has demonstrated the potential of contrastive steering for jailbreaking Large
Language Models (LLMs). However, existing methods rely on limited and inherently biased contrastive
prompts and require laborious manual tuning of steering strength, limiting their robustness and effectiveness. In this paper, we leverage the idea of model extraction to guide the learned steering vectors to approximate the ideal one and propose tuning the steering strength adaptively based on contrastive activations' statistics. Experiments demonstrate that our method notably improves the effectiveness and robustness of probe-based steering, without any extra contrastive
prompts or laborious manual tuning. Being an attack paper, this paper focuses on revealing the breakdown of fortified LLMs, raising the average harmfulness score from 6% to 70%. Our code is available at https://github.com/fhdnskfbeuv/adaptiveSteering.
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Cryptography and Security · Cross-listed from cs.LG
SAGE: Scalable Automatic Gating Ensemble for Confident Negative Harvesting in Fraud Detection
Sudheer Tubati and Amit Goyal
Music streaming fraud, where bad actors artificially inflate stream counts to manipulate chart rankings and royalty payments, poses a significant threat to streaming services and legitimate content creators. Traditional fraud detection approaches struggle with a critical challenge: many legitimate edge cases, including super-fans and sleep-music sessions, exhibit activity patterns that closely mimic those of coordinated fraud. We present SAGE, a novel counterfactual-aware negative harvesting approach that combines SimHash-based stratified sampling with a modular gating ensemble for confident negative identification from unlabeled data. Our ensemble architecture employs pluggable statistical gates (currently instantiated with Mahalanobis distance and k-NN density) with configurable voting thresholds enabling adaptive precision-recall trade-offs. This addresses the representation bias problem in Positive-Unlabeled learning by ensuring comprehensive coverage of rare behavioral cohorts through floor-constrained sampling. Evaluation demonstrates strong precision and recall on held-out data. The approach generalizes across fraud detection domains, achieving strong performance on both customer-level and artist-level fraud without modification to the core methodology.
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Cryptography and Security
BiRD: A Bidirectional Ranking Defense Mechanism for Retrieval Augmented Generation
Chengcai Gao, Zhihong Sun, Xiaochuan Shi et al. (+2 more)
The growing adoption of
Retrieval-Augmented Generation (RAG) has led to a rise in
adversarial attacks. Existing defenses, relying on semantic analysis or voting, face a trade-off between high computational cost and limited robustness under strong poisoning attacks. Their fundamental limitation is the exclusive focus on semantic content relevance, while neglecting the
retrieval context that is critically defined by ranking structures. To this end, we investigate the bidirectional ranking behavior of poisoned and benign documents, and discover a key discriminative pattern: poisoned documents exhibit significantly stronger
alignment between their backward rankings and the query's forward ranking. Capitalizing on this, we propose BiRD, a bidirectional ranking defense mechanism built upon a dual-signal framework that leverages forward ranking to assess semantic content relevance and backward ranking to quantify ranking context consistency. This design directly addresses the fundamental limitation of prior approaches, enabling simultaneous efficiency and robustness. Extensive evaluation across 3
datasets with 3 retrievers and 3 LLMs under 2 attack scenarios validates BiRD's effectiveness. Notably, BiRD reduces the attack success rate of PoisonedRAG by up to 54% while simultaneously improving task accuracy by up to 56%, with average additional latency under 1 second.
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All authors Chengcai Gao, Zhihong Sun, Xiaochuan Shi, Qiufeng Wang, Chao Liang
Cryptography and Security
Hunting Vulnerability Variants in AI Infra: Measurement and Reference-Driven Detection
Tian Dong, Yanjun Chen, Shoufeng Zhang et al. (+6 more)
AI infra has become a shared execution layer for model training, deployment, and
agent orchestration. Because many projects reimplement similar model-centric workflows, a vulnerability disclosed in one repository can recur as a variant in another repository with a related design. Yet the prevalence and detectability of these variants remain poorly understood. This paper presents a measurement study of vulnerability variants in AI infra. Analyzing 688 GitHub repositories and 251 publicly disclosed vulnerabilities, we find that AI infra projects frequently share overlapping functionality and recurrent vulnerable patterns, creating a concrete basis for cross-repository variants. Building on this finding, we study how to automatically identify such variants from known disclosures. We propose INFRASCOPE, a reference-driven multi-
agent framework that extracts transferable vulnerability semantics from known cases and uses them to locate and validate variants in new repositories. Evaluating INFRASCOPE on 20 real-world AI infra repositories, we uncover over 20 vulnerabilities, including 11 acknowledged cases and 4 cases that have been assigned CVEs so far.
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All authors Tian Dong, Yanjun Chen, Shoufeng Zhang, Huaien Zhang, Yunlong Lyu, Keke Lian, Dong Zhang, Shaofeng Li, Hao Chen
Cryptography and Security
Taking Cryptography Out of the Data Path via Near-Memory Processing in DRAM
Nicola Barcarolo, Brahmaiah Gandham, Mohammad Sadrosadati et al. (+3 more)
Cryptographic
algorithms such as AES-128 and SHA-256 are fundamental to ensuring data security and integrity. Although these
algorithms are computationally efficient, their performance is often constrained by the processor-centric architectures (e.g., CPUs, GPUs), primarily due to the
memory bottleneck. This constraint leads to increased latency and higher energy consumption, particularly when handling large volumes of data. To overcome these challenges, Processing-in-
Memory (PIM) has emerged as a promising architectural paradigm, allowing computation to occur directly within or near
memory units. By minimizing data movement between the processor and
memory units, PIM can significantly accelerate cryptographic
algorithms while improving energy efficiency. Several pieces of prior work have demonstrated the effectiveness of PIM at fundamentally accelerating cryptographic
algorithms. However, none of the prior works have extensively demonstrated the potential of a real-world PIM system. In this paper, we want to investigate the potential and limitations of real-world PIM in accelerating cryptographic
algorithms. As part of our methodology, the UPMEM PIM architecture is used to assess the scalability of cryptographic
algorithms. When these
algorithms operate on a single rank, their performance remains below that of modern CPUs. However, distributing the computation across multiple ranks significantly enhances performance. When all available ranks are utilized, real-world PIM can accelerate cryptographic
algorithms more effectively.
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All authors Nicola Barcarolo, Brahmaiah Gandham, Mohammad Sadrosadati, Roberto Passerone, Onur Mutlu, Flavio Vella
Cryptography and Security · Cross-listed from cs.LG
LLM Benchmark Datasets Should Be Contamination-Resistant
Ali Al-Lawati, Jason Lucas, Dongwon Lee et al. (+1 more)
Benchmark datasets are critical for reproducible, reliable, and discriminative evaluation of LLMs. However, recent studies reveal that many
benchmark datasets are included in pretraining corpora, i.e., $\textit{contaminated}$, which diminishes their value as reliable measures of model generalization. In this paper, we argue that
benchmark datasets should be $\textit{contamination-resistant}$, i.e., $\textit{unlearnable}$, but support $\textit{inference}$. To accomplish this, we first highlight the wide prevalence of
benchmark dataset contamination and outline the properties of contamination-resistant
datasets. Second, we highlight how the asymmetry between the inference and training pipelines in the
Transformer architecture can be leveraged to support contamination-resistance. Third, we outline mathematical advancements to make these
datasets interoperable across various LLM architectures. Based on the above, we call on the community to ensure the reliability of LLM benchmarking by: (i) advancing novel contamination-resistant methodologies, (ii) developing supporting methods and platforms, and (iii) adopting contamination-resistant
benchmarks into existing evaluation pipelines.
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All authors Ali Al-Lawati, Jason Lucas, Dongwon Lee, Suhang Wang
Cryptography and Security
DASM: Domain-Aware Sharpness Minimization for Multi-Domain Voice Stream Steganalysis
Pengcheng Zhou, Pianran Guo, Shuhua Chen et al. (+3 more)
The growing use of information hiding in network streaming media for covert communication poses a significant security threat, necessitating the development of robust detection technologies. However, existing steganalysis methods for network voice streams mostly rely on data distributions in specific scenarios, making it difficult to adapt to the practical detection needs of non-homologous data distributions. Through Hessian analysis, we find that the loss landscapes of mainstream models are dominated by numerous saddle points and sharp local minima, rendering them highly sensitive to data distribution shifts and fundamentally limiting generalization. Therefore, we propose a new optimizer, Domain-Aware Sharpness Minimization (DASM). The core mechanisms of DASM consist of two aspects: first, it integrates domain-supervised contrastive learning with sharpness-aware optimization, explicitly preserving inter-domain feature separation while seeking flat minima; second, we design an adaptive domain gap modulation strategy that dynamically calibrates the optimization loss weights by sensing the real-time feature separability of different domains. Extensive experimental results demonstrate that our method outperforms the state-of-the-art methods by a large margin and achieves excellent generalization and robustness.
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All authors Pengcheng Zhou, Pianran Guo, Shuhua Chen, Mengqin Zhao, Zhongliang Yang, Linna Zhou
Cryptography and Security
reconCTI: A Proactive Approach to Cyber-Threat Intelligence
Mohammed Mahir Rahman, Shahzad Memon, Tauseef Ahmed et al. (+1 more)
The rapid advancement of information technology has introduced a noticeable shift from traditional offline practices to more efficient and interconnected online environments. This transition, while offering convenience, has also increased exposure to various cyber threats such as identity theft, impersonation, and phishing scams. Reconnaissance, or briefly known as information gathering, is a key stage for threat actors, often relying on open-source intelligence (OSINT) to collect sensitive and extensive data on targets. In response to this challenge, this study introduces reconCTI, a command-line tool built using Python for Linux systems. The tool is designed to search for sensitive data leaks across both surface web and dark web platforms. It allows users to input specific keywords, scan multiple sites at once, and then assess the findings by referencing the MITRE ATT&CK framework. The results are compiled into a threat report that also includes possible mitigation strategies. reconCTI is intended to support both cybersecurity professionals and individuals in identifying risks early and taking appropriate action.
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All authors Mohammed Mahir Rahman, Shahzad Memon, Tauseef Ahmed, Ameer Al-Nemrat
Cryptography and Security · Cross-listed from eess.IV
Set Shaping Theory as a Complementary Payload-Shaping Layer for Steganography
Aida Koch, Logan Lewis, Lily Scott et al. (+1 more)
This paper studies the use of Set Shaping Theory (SST) as a reversible payload-shaping layer for least significant bit (LSB) image steganography. The proposal is not intended to replace existing steganographic methods or to compete with them as a new
embedding scheme. Instead, SST is positioned as a complementary preprocessing stage that makes an existing
embedding method easier to apply with lower statistical disturbance. The SST transformation increases the message length by K symbols and is implemented with the approximate and fast transformation
algorithm developed by Glen Tankersley. Although the embedded payload is lengthened from N to N+K bits, the selected representation can reduce D_KL(P||Q) and therefore make the subsequent steganographic insertion less detectable under histogram-based criteria. Across 1,800 controlled simulations on four synthetic cover-image models, SST reduced D_KL(P||Q) by an average of 25.16 percent relative to a fair N+K LSB baseline, with a 95 percent confidence interval of +/- 1.22 percent. For K=8, the average reduction reached 42.81 percent. Additional robustness simulations with keyed random
embedding paths confirmed the effect across several distances: at K=8, SST reduced KL divergence by 42.44 percent, Jensen-Shannon divergence by 29.62 percent, total variation by 12.41 percent, and symmetric chi-square distance by 28.30 percent. An additional image-based
matrix-
embedding/STC-like simulation showed that SST also reduces the minimum weighted insertion cost: relative to the unshaped K=0 reference, K=8 reduced the cost by 6.93 percent.
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All authors Aida Koch, Logan Lewis, Lily Scott, Agi Weber
Cryptography and Security
Auditing Privacy in Multi-Tenant RAG under Account Collusion
Florian A. D. Burnat
Multi-tenant RAG services often treat the account as the
privacy boundary: each account receives an $(\varepsilon_{\text{acc}},\delta_{\text{acc}})$-DP
retrieval guarantee against the tenant index. We show that this framing understates leakage under same-index account collusion. For Gaussian noise-then-select
retrieval, $k$ coordinated same-tenant accounts compose to joint leakage $\Theta(\sqrt{k}\,\varepsilon_{\text{acc}})$, not $\varepsilon_{\text{acc}}$; we give a matching membership-inference attack and validate the predicted $\sqrt{k}$ AUC trend in scalar, top-$K$, trained-embedder, and production-scale HNSW settings. We then give a verifier-runnable audit protocol that attests noise-then-select
retrieval and reports $(\textsf{PASS},\varepsilon_{\text{audit}})$ for coalitions up to a declared cap $k_{\max}$, without disclosing the index or changing the
retrieval decision rule. The claim is
retrieval-channel only: generation-channel leakage and adversarially robust coalition-size estimation are complementary audit predicates.
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Cryptography and Security · Cross-listed from cs.GT
The Privacy Subsidy in Glosten-Milgrom: Bid-Ask Spread and Welfare under Flip-Noise Direction Observation
Yuki Nakamura
We derive a closed-form bid-ask spread and welfare decomposition for the Glosten-Milgrom 1985 sequential-trading model when the
market maker observes the trade direction perturbed by a binary flip channel of probability $\eta$ – a natural information-theoretic model of
privacy mechanisms acting on the direction signal. Under a committed
Bayesian market-maker pricing rule, the
equilibrium spread is $\mu(1-2\eta)\Delta$, where $\mu$ is the informed-trader fraction and $\Delta = v_H - v_L$ the value range. The welfare decomposition identifies a per-trade transfer $\mu\eta\Delta$ from the protocol's liquidity pool to traders – the "
privacy subsidy", mirroring the Gaussian-Kyle analog established in prior work. The result extends the
privacy-subsidy concept from continuous Gaussian to discrete two-state microstructure, demonstrating robustness across both classical models. Primary application: MPC-based matching engines with $\varepsilon$-differentially-private direction disclosure, where the engine prices on a noisy direction signal.
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Cryptography and Security
Measuring Safety Alignment Effects in Autonomous Security Agents
Isaac David and Arthur Gervais
Do stock safety-aligned
language models and their uncensored or abliterated derivatives behave differently when run as autonomous security
agents? Single-turn refusal
benchmarks cannot answer this question: security
agents must inspect repositories, call tools, and produce vulnerability evidence inside authorized sandboxes. We present a trace-based
benchmark of 30 local vulnerability-analysis tasks with fixed tools, deterministic success predicates, redaction rules, and grounding checks, and compare four stock models against uncensored or abliterated derivatives: Gemma 4 31B, Gemma 4 26B A4B, Qwen2.5-Coder 7B, and Llama 3.1 8B. The artifact contains 1,500 security-
agent traces and 800 non-security control traces. The Gemma pairs show large less-restricted gains on security tasks: 14.0% versus 0.7% success for 31B and 10.7% versus 0.0% for 26B, with higher mean grounding (3.91 versus 3.27 and 4.12 versus 1.64 out of five) and 0.0% refusal, suppressed-action, and unsafe-action rates in the 31B traces. However, controls and non-Gemma pairs rule out a clean security-specific or universal less-restricted effect: Gemma gaps also appear on ordinary coding tasks, Qwen2.5-Coder success is lower for the less-restricted derivative (2.0% versus 5.3%), and the abliterated Llama derivative fails the tool protocol. Across all families, hard proof-of-trigger and patch-verification tasks remain unsolved. These results show that safety
alignment effects in autonomous security
agents should be measured at the system level, separating refusal, unsafe action, tool reliability, and evidence grounding rather than treating refusal rate as the safety signal.
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Cryptography and Security
Security Analysis of Bitcoin's V2 Transport Protocol: Exploiting Design Implications for Sustained Eclipse and Downgrade Attacks
Charmaine Ndolo and Florian Tschorsch
Bitcoin recently introduced a new protocol for the encryption of peer-to-peer (P2P) communication. The protocol, known as V2 P2P transport, represents a big step towards securing the overlay network against various previously-known attack vectors. Based on an analysis of V2 P2P transport, this work examines the current viability of said attacks and concludes that while they are now remediated, alternative attacks and paths to similar objectives exist. The identified shortcomings are conceptual (and not implementation bugs) and even applicable to other P2P networks. We show how a network-level attacker can identify application messages using the length of TCP payloads, can eclipse a target node by taking advantage of how encrypted communication channels work and can downgrade all of a node's connections to the unencrypted protocol by using the mechanisms designed for compatibility. We validate our contributions using a combination of network measurements, emulations and simulations. Finally, we propose a series of short-term and long-term countermeasures towards securing Bitcoin's P2P network. To the best of our knowledge, we are the first to study Bitcoin's security under V2 P2P transport.
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