arXiv subjects

Rahul Chatterjee

Publications and source records attributed to Rahul Chatterjee.

9 recordsLinked to original sources

arXiv2026

"Lighting The Way For Those Not Here": How Technology Researchers Can Help Fight the Missing and Murdered Indigenous Relatives (MMIR) Crisis

Indigenous peoples across Turtle Island (North America) face disproportionate rates of disappearance and murder, a "genocide" rooted in settler-colonial violence and systemic erasure. Technology plays a crucial role in the Missing and Murdered Indigenous Relatives (MMIR) crisis: perpetuating harm and impeding investigations, yet enabling advocacy and resistance. Communities utilize technologies such as AMBER alerts, news websites, social media groups, and campaigns (like #MMIW, #MMIWR, #NoMoreStolenSisters, and #NoMoreStolenDaughters) to mobilize searches, amplify awareness, and honor missing relatives. Yet, little research in HCI has critically examined technology's role in shaping the MMIR crisis by centering community voices. Through a large-scale study, we analyze 140 webpages to identify systemic, technological, and institutional barriers that hinder communities' efforts, while highlighting socio-technical actions that foster healing and safety. Finally, we amplify Indigenous voices by providing a dataset of stories that resist epistemic erasure, along with recommendations for HCI researchers to support Indigenous-led initiatives with cultural sensitivity, accountability, and self-determination.

cs.CY↗

arXiv2026

Assessing LLM Response Quality in the Context of Technology-Facilitated Abuse

Technology-facilitated abuse (TFA) is a pervasive form of intimate partner violence (IPV) that leverages digital tools to control, surveil, or harm survivors. While tech clinics are one of the reliable sources of support for TFA survivors, they face limitations due to staffing constraints and logistical barriers. As a result, many survivors turn to online resources for assistance. With the growing accessibility and popularity of large language models (LLMs), and increasing interest from IPV organizations, survivors may begin to consult LLM-based chatbots before seeking help from tech clinics. In this work, we present the first expert-led manual evaluation of four LLMs - two widely used general-purpose non-reasoning models and two domain-specific models designed for IPV contexts - focused on their effectiveness in responding to TFA-related questions. Using real-world questions collected from literature and online forums, we assess the quality of zero-shot single-turn LLM responses generated with a survivor safety-centered prompt on criteria tailored to the TFA domain. Additionally, we conducted a user study to evaluate the perceived actionability of these responses from the perspective of individuals who have experienced TFA. Our findings, grounded in both expert assessment and user feedback, provide insights into the current capabilities and limitations of LLMs in the TFA context and may inform the design, development, and fine-tuning of future models for this domain. We conclude with concrete recommendations to improve LLM performance for survivor support.

cs.HC↗

arXiv2025

Privacy-Preserving Performance Profiling of In-The-Wild GPUs

GPUs are the dominant platform for many important applications today including deep learning, accelerated computing, and scientific simulation. However, as the complexity of both applications and hardware increases, GPU chip manufacturers face a significant challenge: how to gather comprehensive performance characteristics and value profiles from GPUs deployed in real-world scenarios. Such data, encompassing the types of kernels executed and the time spent in each, is crucial for optimizing chip design and enhancing application performance. Unfortunately, despite the availability of low-level tools like NSYS and NCU, current methodologies fall short, offering data collection capabilities only on an individual user basis rather than a broader, more informative fleet-wide scale. This paper takes on the problem of realizing a system that allows planet-scale real-time GPU performance profiling of low-level hardware characteristics. The three fundamental problems we solve are: i) user experience of achieving this with no slowdown; ii) preserving user privacy, so that no 3rd party is aware of what applications any user runs; iii) efficacy in showing we are able to collect data and assign it applications even when run on 1000s of GPUs. Our results simulate a 100,000 size GPU deployment, running applications from the Torchbench suite, showing our system addresses all 3 problems.

cs.AR↗

arXiv2023

Compact: Approximating Complex Activation Functions for Secure Computation

Secure multi-party computation (MPC) techniques can be used to provide data privacy when users query deep neural network (DNN) models hosted on a public cloud. State-of-the-art MPC techniques can be directly leveraged for DNN models that use simple activation functions such as ReLU. However, these techniques are ineffective and/or inefficient for the complex and highly non-linear activation functions used in cutting-edge DNN models. We present Compact, which produces piece-wise polynomial approximations of complex AFs to enable their efficient use with state-of-the-art MPC techniques. Compact neither requires nor imposes any restriction on model training and results in near-identical model accuracy. To achieve this, we design Compact with input density awareness and use an application-specific simulated annealing type optimization to generate computationally more efficient approximations of complex AFs. We extensively evaluate Compact on four different machine-learning tasks with DNN architectures that use popular complex AFs silu, gelu, and mish. Our experimental results show that Compact incurs negligible accuracy loss while being 2x-5x computationally more efficient than state-of-the-art approaches for DNN models with large number of hidden layers. Our work accelerates easy adoption of MPC techniques to provide user data privacy even when the queried DNN models consist of a number of hidden layers and trained over complex AFs.

cs.CR↗

arXiv2023

MASCARA: Systematically Generating Memorable And Secure Passphrases

Passwords are the most common mechanism for authenticating users online. However, studies have shown that users find it difficult to create and manage secure passwords. To that end, passphrases are often recommended as a usable alternative to passwords, which would potentially be easy to remember and hard to guess. However, as we show, user-chosen passphrases fall short of being secure, while state-of-the-art machine-generated passphrases are difficult to remember. In this work, we aim to tackle the drawbacks of the systems that generate passphrases for practical use. In particular, we address the problem of generating secure and memorable passphrases and compare them against user chosen passphrases in use. We identify and characterize 72, 999 user-chosen in-use unique English passphrases from prior leaked password databases. Then we leverage this understanding to create a novel framework for measuring memorability and guessability of passphrases. Utilizing our framework, we design MASCARA, which follows a constrained Markov generation process to create passphrases that optimize for both memorability and guessability. Our evaluation of passphrases shows that MASCARA-generated passphrases are harder to guess than in-use user-generated passphrases, while being easier to remember compared to state-of-the-art machine-generated passphrases. We conduct a two-part user study with crowdsourcing platform Prolific to demonstrate that users have highest memory-recall (and lowest error rate) while using MASCARA passphrases. Moreover, for passphrases of length desired by the users, the recall rate is 60-100% higher for MASCARA-generated passphrases compared to current system-generated ones.

cs.CR↗

arXiv2022

Experimental Security Analysis of the App Model in Business Collaboration Platforms

Business Collaboration Platforms like Microsoft Teams and Slack enable teamwork by supporting text chatting and third-party resource integration. A user can access online file storage, make video calls, and manage a code repository, all from within the platform, thus making them a hub for sensitive communication and resources. The key enabler for these productivity features is a third-party application model. We contribute an experimental security analysis of this model and the third-party apps. Performing this analysis is challenging because commercial platforms and their apps are closed-source systems. Our analysis methodology is to systematically investigate different types of interactions possible between apps and users. We discover that the access control model in these systems violates two fundamental security principles: least privilege and complete mediation. These violations enable a malicious app to exploit the confidentiality and integrity of user messages and third-party resources connected to the platform. We construct proof-of-concept attacks that can: (1) eavesdrop on user messages without having permission to read those messages; (2) launch fake video calls; (3) automatically merge code into repositories without user approval or involvement. Finally, we provide an analysis of countermeasures that systems like Slack and Microsoft Teams can adopt today.

cs.CR↗

arXiv2020

Data Privacy in Trigger-Action Systems

Trigger-action platforms (TAPs) allow users to connect independent web-based or IoT services to achieve useful automation. They provide a simple interface that helps end-users create trigger-compute-action rules that pass data between disparate Internet services. Unfortunately, TAPs introduce a large-scale security risk: if they are compromised, attackers will gain access to sensitive data for millions of users. To avoid this risk, we propose eTAP, a privacy-enhancing trigger-action platform that executes trigger-compute-action rules without accessing users' private data in plaintext or learning anything about the results of the computation. We use garbled circuits as a primitive, and leverage the unique structure of trigger-compute-action rules to make them practical. We formally state and prove the security guarantees of our protocols. We prototyped eTAP, which supports the most commonly used operations on popular commercial TAPs like IFTTT and Zapier. Specifically, it supports Boolean, arithmetic, and string operations on private trigger data and can run 100% of the top-500 rules of IFTTT users and 93.4% of all publicly-available rules on Zapier. Based on ten existing rules that exercise a wide variety of operations, we show that eTAP has a modest performance impact: on average rule execution latency increases by 70 ms (55%) and throughput reduces by 59%.

cs.CR↗

arXiv2020

Invisible Perturbations: Physical Adversarial Examples Exploiting the Rolling Shutter Effect

Physical adversarial examples for camera-based computer vision have so far been achieved through visible artifacts -- a sticker on a Stop sign, colorful borders around eyeglasses or a 3D printed object with a colorful texture. An implicit assumption here is that the perturbations must be visible so that a camera can sense them. By contrast, we contribute a procedure to generate, for the first time, physical adversarial examples that are invisible to human eyes. Rather than modifying the victim object with visible artifacts, we modify light that illuminates the object. We demonstrate how an attacker can craft a modulated light signal that adversarially illuminates a scene and causes targeted misclassifications on a state-of-the-art ImageNet deep learning model. Concretely, we exploit the radiometric rolling shutter effect in commodity cameras to create precise striping patterns that appear on images. To human eyes, it appears like the object is illuminated, but the camera creates an image with stripes that will cause ML models to output the attacker-desired classification. We conduct a range of simulation and physical experiments with LEDs, demonstrating targeted attack rates up to 84%.

cs.CV↗

arXiv2019

Protocols for Checking Compromised Credentials

To prevent credential stuffing attacks, industry best practice now proactively checks if user credentials are present in known data breaches. Recently, some web services, such as HaveIBeenPwned (HIBP) and Google Password Checkup (GPC), have started providing APIs to check for breached passwords. We refer to such services as compromised credential checking (C3) services. We give the first formal description of C3 services, detailing different settings and operational requirements, and we give relevant threat models. One key security requirement is the secrecy of a user's passwords that are being checked. Current widely deployed C3 services have the user share a small prefix of a hash computed over the user's password. We provide a framework for empirically analyzing the leakage of such protocols, showing that in some contexts knowing the hash prefixes leads to a 12x increase in the efficacy of remote guessing attacks. We propose two new protocols that provide stronger protection for users' passwords, implement them, and show experimentally that they remain practical to deploy.

cs.CR↗