Cryptography and Security · Cross-listed from cs.LG
Temporal Contrastive Transformer for Financial Crime Detection: Self-Supervised Sequence Embeddings via Predictive Contrastive Coding
Danny Butvinik, Yonit Marcus, Nitzan Tal et al. (+1 more)
We introduce the Temporal Contrastive
Transformer (TCT), a representation learning framework designed to capture contextual temporal dynamics in sequences of financial transactions. The model is trained using a self-supervised contrastive objective to produce
embeddings that encode behavioral patterns over time, with the goal of supporting downstream fraud detection tasks. We evaluate TCT in a realistic setting by using the learned
embeddings as input features to a gradient boosting classifier. Experimental results show that
embeddings alone achieve meaningful predictive performance (AUC 0.8644), indicating that the model captures non-trivial temporal structure. However, when combined with domain-engineered features, no measurable improvement is observed over the baseline (AUC 0.9205 vs. 0.9245), suggesting that the learned representations largely overlap with existing feature abstractions. These findings position TCT as a promising representation learning approach that captures relevant behavioral signal, while highlighting the challenges of achieving additive value over strong domain features. The results reflect an intermediate stage in the development of temporal representation learning for financial crime detection and motivate further research on model architecture, training objectives, and integration strategies. At this early stage, achieving performance comparable to a strong feature-engineered baseline is itself a meaningful outcome, indicating that learned representations approximate domain-specific features without manual engineering. While not yet production-ready, these results point to a promising direction for reducing reliance on feature engineering in financial crime detection.
Read the full abstract ▾
All authors Danny Butvinik, Yonit Marcus, Nitzan Tal, Gabrielle Azoulay
Cryptography and Security · Cross-listed from cs.CL
Can LLMs Infer Conversational Agent Users' Personality Traits from Chat History?
Derya Cögendez, Verena Zimmermann and Noé Zufferey
Sensitive information, such as knowledge about an individual's personality, can be can be misused to influence behavior (e.g., via personalized messaging). To assess to what extent an individual's personality can be inferred from user interactions with LLM-based conversational
agents (CAs), we analyze and quantify related
privacy risks of using CAs. We collected actual ChatGPT logs from N=668 participants, containing 62,090 individual chats, and report statistics about the different types of shared data and use cases. We fine-tuned RoBERTa-base text classification models to infer personality traits from CA interactions. The findings show that these models achieve trait inference with accuracy (ternary classification) better than random in multiple cases. For example, for extraversion, accuracy improves by +44% relative to the baseline on interactions for relationships and personal reflection. This research highlights how interactions with CAs pose
privacy risks and provides fine-grained insights into the level of risk associated with different types of interactions.
Read the full abstract ▾
Cryptography and Security
Backdoor Attacks on Decentralised Post-Training
Oğuzhan Ersoy, Nikolay Blagoev, Jona te Lintelo et al. (+3 more)
Decentralised post-training of large
language models utilises data and pipeline parallelism techniques to split the data and the model. Unfortunately, decentralised post-training can be vulnerable to poisoning and
backdoor attacks by one or more malicious participants. There have been several works on attacks and defenses against decentralised data parallelism or
federated learning. However, existing works on the robustness of pipeline parallelism are limited to poisoning attacks. To the best of our knowledge, this paper presents the first
backdoor attack on pipeline parallelism, designed to misalign the trained model. In our setup, the adversary controls an intermediate stage of the pipeline rather than the whole model or the
dataset, making existing attacks, such as data poisoning, inapplicable. Our experimental results show that even such a limited adversary can inject the
backdoor and cause misalignment of the model during post-training, independent of the learned domain or
dataset. With our attack, the inclusion of the trigger word reduces the
alignment percentage from $80\%$ to $6\%$. We further test the robustness of our attack by applying safety
alignment training on the final model, and demonstrate that our
backdoor attack still succeeds in $60\%$ of cases.
Read the full abstract ▾
All authors Oğuzhan Ersoy, Nikolay Blagoev, Jona te Lintelo, Stefanos Koffas, Marina Krček, Stjepan Picek
Cryptography and Security
Cybersecurity Risk Assessment for CubeSat Missions: Adapting Established Frameworks for Resource-Constrained Environments
Jonathan Shelby
CubeSats have democratised access to space for universities, start-ups and emerging space nations, but the same design decisions that reduce cost and complexity introduce distinctive cybersecurity risks. Existing risk assessment frameworksNIST SP 800-37/53 [1, 2], ISO/IEC 27001/27005 [3, 4] and supply-chain guidance such as NIST SP 800-161 [5]assume abundant computational resources, centralised monitoring and mature governance structures that do not hold for power-limited, intermittently connected CubeSat missions. This paper develops a contextually appropriate risk assessment framework tailored to CubeSat environments, grounded in a 42-entry vulnerability register coded using STRIDE [6], MITRE ATT&CK [7] and CVSS v3.1 [8]. The register reveals that risks concentrate in communication and ground segments (mean CVSS 8.08.2) rather than distributing uniformly across subsystems. The framework introduces two constructs: a Security-per-Watt (SpW) heuristic that quantities security benefit per unit power, and a Distributed Security Paradigm (DSP) that reconceptualises incident response as an autonomous, constellation-level function rather than a purely ground-centric process. Scenario-based analysis demonstrates that adapted controls and distributed incident handling can achieve up to 2.7X higher SpW for cryptographic choices and 1.98X higher SpW for incident-response strategies compared with naive terrestrial transpositions, while remaining feasible for typical CubeSat power and governance constraints. The approach provides mission designers, operators and regulators with proportionate, auditable guidance, and offers a reusable pattern for adapting enterprise security frameworks to other severely constrained cyber-physical systems.
Read the full abstract ▾
Cryptography and Security
On the Necessity of Pre-agreed Secrets for Thwarting Last-minute Coercion: Vulnerabilities and Lessons From the Loki E-voting Protocol
Jingxin Qiao, Myrto Arapinis and Thomas Zacharias
Coercion-resistance (CR) is a crucial security property in e-voting systems. It ensures that an attacker cannot compel a voter to vote in a specific way by using threats or rewards. The Loki e-voting protocol, proposed by Giustolisi et al. at IEEE S&P (2024), introduces a novel design that mitigates last-minute coercion through a re-voting mechanism. It also aims to address the usability issues of the seminal JCJ e-voting protocol, specifically: i) the requirement that voters can store and hide pre-agreed credentials, and ii) the ability of voters to convincingly lie while being coerced. In this work, we identify two vulnerabilities in Loki. The first is a brute-force attack that compromises the integrity of the evasion strategy. Specifically, this attack allows an adversary to cast a ballot on behalf of their victim in a way that the evasion strategy cannot defend against, rendering it ineffective. The second vulnerability is a forced abstention attack, which allows an adversary to detect when their victim has complied with their instruction not to vote. We generalise the integrity attack to reveal a fundamental dilemma: without pre-agreed secret credentials, it is not possible to prevent last-minute coercion. Finally, we show how reverting to pre-agreed secret credentials fixes the aforementioned vulnerabilities and discuss the trade-off between tallying efficiency and stronger trust assumptions.
Read the full abstract ▾
Cryptography and Security
NFC based inventory control system for secure and efficient communication
Razi Iqbal, Awais Ahmad and Asfandyar Gillani
This paper brings up this idea of using Near Field Communication (NFC) for inventory control system instead of using traditional barcodes. NFC because of its high security, ease of use and efficiency can be very suitable for systems like inventory control. In traditional inventory control systems, each product has a barcode pasted on it, which is vulnerable to attacks as barcodes are open and have no security. Furthermore, barcodes are prone to damages and can be unreliable when pasted on different types of products e.g. hot and frozen products, circular shaped products and irregular shaped products like clothes etc. NFC on the other hand is very efficient, secure and reliable when it comes to short-range wireless communication. In this paper we will present our prototype for the inventory control system of an electronic store in which each product has a passive NFC tag pasted to it. When a customer buys a product the receipt of the product is generated using NFC between the NFC passive tag on the product and NFC enabled device (e.g. smart phone or reader) at the cash counter.
Read the full abstract ▾
Cryptography and Security
Beyond Latency: A System-Level Characterization of MPC and FHE for PPML
Pengzhi Huang, Kiwan Maeng and G. Edward Suh
Privacy protection has become an increasing concern in modern machine learning applications.
Privacy-preserving machine learning (PPML) has attracted growing research
attention, with approaches such as secure multiparty computation (MPC) and fully homomorphic encryption (FHE) being actively explored. However, existing evaluations of these approaches have frequently been done on a narrow, fragmented setup and only focused on a specific performance metric, such as the online inference latency of a specific batch size. From the existing reports, it is hard to compare different approaches, especially when considering other metrics like energy/cost or broader system setups (various hyperparameters, offline overheads, future hardware/network configurations, etc.). We present a unified characterization of three popular approaches – two variants of MPC based on arithmetic/binary sharing conversion and function secret sharing, and FHE – on their performance and cost in performing
privacy-preserving inference on multiple CNN and
Transformer models. We study a range of LAN and WAN environments, model sizes, batch sizes, and input sequence lengths. We evaluate not only the performance but also the energy consumption and monetary cost of deploying under a realistic scenario, taking into account their offline and online computation/communication overheads. We provide empirical guidance for selecting, optimizing, and deploying these
privacy-preserving compute paradigms, and outline how evolving hardware and network trends are likely to shift trade-offs between the two MPC schemes and FHE. This work provides system-level insights for researchers and practitioners who seek to understand or accelerate PPML workloads.
Read the full abstract ▾
Cryptography and Security
Efficient Software Vulnerability Detection Using Transformer-based Models
Sameer Shaik, Zhen Huang, Daniela Stan Raicu et al. (+1 more)
Detecting software vulnerabilities is critical to ensuring the security and reliability of modern computer systems. Deep neural networks have shown promising results on vulnerability detection, but they lack the capability to capture global contextual information on vulnerable code. To address this limitation, we explore the application of
transformers for C/C++ vulnerability detection. We use program slices that encapsulate key syntactic and semantic features of program code, such as API function calls, array usage, pointer manipulations, and arithmetic expressions. By leveraging
transformers' capability to capture both local and global contextual information on vulnerable code, our work can identify vulnerabilities accurately. Combined with data balancing and hyperparameter fine-tuning, our work offers a robust and efficient approach to identifying vulnerable code with moderate resource usage and training time.
Read the full abstract ▾
All authors Sameer Shaik, Zhen Huang, Daniela Stan Raicu, Jacob Furst
Cryptography and Security
When Labels Are Scarce: A Systematic Mapping of Label-Efficient Code Vulnerability Detection
Noor Khalal, Chakib Fettal, Lazhar Labiod et al. (+1 more)
Machine-learning-based code vulnerability detection (CVD) has progressed rapidly, from deep program representations to pretrained code models and LLM-centered pipelines. Yet dependable vulnerability labeling remains expensive, noisy, and uneven across projects,
languages, and CWE types, motivating approaches that reduce reliance on human labeling. This survey maps these approaches, synthesizing five paradigm families and the mechanisms they use. It connects mechanisms to
token, graph, hybrid, and knowledgebased representations, and consolidates evaluation and reporting axes that limit comparison (label-budget specification, compute/cost assumptions, leakage, and granularity mismatches). A Design Map and constraintfirst Decision Guide distill trade-offs and failure modes for practical method selection.
Read the full abstract ▾
All authors Noor Khalal, Chakib Fettal, Lazhar Labiod, Mohamed Nadif
Cryptography and Security
Cybercrime as a Service: A Scoping Review
Ema Mauko, Shane D Johnson and Enrico Mariconti
Cloud computing has drastically altered the ways in which it is possible to deliver information technologies in a service-led structure, however, this has also been reflected in the cybercrime domain. Cybercrime as a Service is an economic model where a technically skilled actor offers a given cyberattack as an end-to-end service to non-technical actors who pay a subscription fee for said service. The services, which can vary in scope, targets, and delivery modes, include everything from the vulnerability discoveries, delivery of the attack, and the attack itself to financial rewards to the subscriber. In this scoping literature review, we analysed 195 articles from both academic and grey literature with a view of investigating the services articles studied, the methodological approach the how the CaaS model is predicted to develop in the future. Our review indicates that with further commercialisation of the model will further lower the barrier of entry to the cybercrime realm, increase sophistication of the attacks and increase resilience of the service providers and their ecosystem which will result in harder shutdowns of services by the authorities. Furthermore, as the model becomes more accessible, groups such as organised crime groups, extremist actors may use them as well, which may have implications for criminal activity in both cyber and physical domains.
Read the full abstract ▾
Cryptography and Security
EnsembleSHAP: Faithful and Certifiably Robust Attribution for Random Subspace Method
Yanting Wang and Jinyuan Jia
Random subspace method has wide security applications such as providing certified defenses against
adversarial and
backdoor attacks, and building robustly aligned LLM against jailbreaking attacks. However, the explanation of random subspace method lacks sufficient exploration. Existing state-of-the-art feature attribution methods, such as Shapley value and LIME, are computationally impractical and lacks security guarantee when applied to random subspace method. In this work, we propose EnsembleSHAP, an intrinsically faithful and secure feature attribution for random subspace method that reuses its computational byproducts. Specifically, our feature attribution method is 1) computationally efficient, 2) maintains essential properties of effective feature attribution (such as local accuracy), and 3) offers guaranteed protection against
privacy-preserving attacks on feature attribution methods. To the best of our knowledge, this is the first work to establish provable robustness against explanation-preserving attacks. We also perform comprehensive evaluations for our explanation's effectiveness when faced with different empirical attacks, including
backdoor attacks,
adversarial attacks, and jailbreak attacks. The code is at https://github.com/Wang-Yanting/EnsembleSHAP. WARNING: This document may include content that could be considered harmful.
Read the full abstract ▾
Cryptography and Security · Cross-listed from cs.LG
Refined Detection for Gumbel Watermarking
Tor Lattimore
We propose a simple detection mechanism for the Gumbel watermarking scheme proposed by Aaronson (2022). The new mechanism is proven to be near-optimal in a problem-dependent sense among all model-agnostic watermarking schemes under the assumption that the next-
token distribution is sampled i.i.d.
Read the full abstract ▾
Cryptography and Security
Architecting Secure AI Agents: Perspectives on System-Level Defenses Against Indirect Prompt Injection Attacks
Chong Xiang, Drew Zagieboylo, Shaona Ghosh et al. (+5 more)
AI
agents, predominantly powered by large
language models (LLMs), are vulnerable to indirect
prompt injection, in which malicious instructions embedded in untrusted data can trigger dangerous
agent actions. This position paper discusses our
vision for system-level defenses against indirect
prompt injection attacks. We articulate three positions: (1) dynamic replanning and security policy updates are often necessary for dynamic tasks and realistic environments; (2) certain context-dependent security decisions would still require LLMs (or other learned models), but should only be made within system designs that strictly constrain what the model can observe and decide; (3) in inherently ambiguous cases, personalization and human interaction should be treated as core design considerations. In addition to our main positions, we discuss limitations of existing
benchmarks that can create a false sense of utility and security. We also highlight the value of system-level defenses, which serve as the skeleton of agentic systems by structuring and controlling
agent behaviors, integrating rule-based and model-based security checks, and enabling more targeted research on model robustness and human interaction.
Read the full abstract ▾
All authors Chong Xiang, Drew Zagieboylo, Shaona Ghosh, Sanjay Kariyappa, Kai Greshake, Hanshen Xiao, Chaowei Xiao, G. Edward Suh
Cryptography and Security
Security and Privacy in Virtual and Robotic Assistive Systems: A Comparative Framework
Nelly Elsayed
Assistive technologies increasingly support independence, accessibility, and safety for older adults, people with disabilities, and individuals requiring continuous care. Two major categories are virtual assistive systems and robotic assistive systems operating in physical environments. Although both offer significant benefits, they introduce important security and
privacy risks due to their reliance on artificial intelligence, network connectivity, and sensor-based perception. Virtual systems are primarily exposed to threats involving data
privacy, unauthorized access, and
adversarial voice manipulation. In contrast, robotic systems introduce additional cyber-physical risks such as sensor spoofing, perception manipulation, command injection, and physical safety hazards. In this paper, we present a comparative analysis of security and
privacy challenges across these systems. We develop a unified comparative threat-modeling framework that enables structured analysis of attack surfaces, risk profiles, and safety implications across both systems. Moreover, we provide design recommendations for developing secure,
privacy-preserving, and trustworthy assistive technologies.
Read the full abstract ▾