arXiv subjects

Nirvan Tyagi

Publications and source records attributed to Nirvan Tyagi.

4 recordsLinked to original sources

arXiv2025

From Inquisitorial to Adversarial: Using Legal Theory to Redesign Online Reporting Systems

User reporting systems play a central role in how online communities address interpersonal conflict and harassment, especially in private spaces such as direct messages, voice chats, and end-to-end encrypted messaging. These settings complicate evidence collection for community moderators while heightening users' concerns about procedural justice and privacy. To examine these challenges, we draw on adversarial legal frameworks from offline judicial systems and apply them to community-level reporting systems, using Discord as a research site. We find that online community reporting systems often follow an inquisitorial model, in which moderators lead evidence collection and case development, rather than an adversarial model, which gives users greater control over how evidence is presented and contested. Although adversarial practices can strengthen procedural justice and protect privacy, they can also introduce new risks of abuse, underscoring the need for careful threat modeling. Building on this analysis, we present a design space for giving users greater control over the disclosure and authentication of evidence while accounting for the privacy constraints and technical affordances of online communities. We conclude by discussing how this design space can inform platform-level reporting systems and how cryptographic techniques may help reinforce these systems amid growing distrust in platforms.

cs.HC↗

arXiv2024

Private Hierarchical Governance for Encrypted Messaging

The increasing harms caused by hate, harassment, and other forms of abuse online have motivated major platforms to explore hierarchical governance. The idea is to allow communities to have designated members take on moderation and leadership duties; meanwhile, members can still escalate issues to the platform. But these promising approaches have only been explored in plaintext settings where community content is public to the platform. It is unclear how one can realize hierarchical governance in the huge and increasing number of online communities that utilize end-to-end encrypted (E2EE) messaging for privacy. We propose private hierarchical governance systems. These should enable similar levels of community governance as in plaintext settings, while maintaining cryptographic privacy of content and governance actions not reported to the platform. We design the first such system, taking a layered approach that adds governance logic on top of an encrypted messaging protocol; we show how an extension to the message layer security (MLS) protocol suffices for achieving a rich set of governance policies. Our approach allows developers to rapidly prototype new governance features, taking inspiration from a plaintext system called PolicyKit. We build a prototype E2EE messaging system called MlsGov that supports content-based community and platform moderation, elections of community moderators, votes to remove abusive users, and more.

cs.CR↗

arXiv2016

Energy-Efficient Algorithms

We initiate the systematic study of the energy complexity of algorithms (in addition to time and space complexity) based on Landauer's Principle in physics, which gives a lower bound on the amount of energy a system must dissipate if it destroys information. We propose energy-aware variations of three standard models of computation: circuit RAM, word RAM, and transdichotomous RAM. On top of these models, we build familiar high-level primitives such as control logic, memory allocation, and garbage collection with zero energy complexity and only constant-factor overheads in space and time complexity, enabling simple expression of energy-efficient algorithms. We analyze several classic algorithms in our models and develop low-energy variations: comparison sort, insertion sort, counting sort, breadth-first search, Bellman-Ford, Floyd-Warshall, matrix all-pairs shortest paths, AVL trees, binary heaps, and dynamic arrays. We explore the time/space/energy trade-off and develop several general techniques for analyzing algorithms and reducing their energy complexity. These results lay a theoretical foundation for a new field of semi-reversible computing and provide a new framework for the investigation of algorithms.

cs.DS↗

arXiv2016

Toward an Energy Efficient Language and Compiler for (Partially) Reversible Algorithms

We introduce a new programming language for expressing reversibility, Energy-Efficient Language (Eel), geared toward algorithm design and implementation. Eel is the first language to take advantage of a partially reversible computation model, where programs can be composed of both reversible and irreversible operations. In this model, irreversible operations cost energy for every bit of information created or destroyed. To handle programs of varying degrees of reversibility, Eel supports a log stack to automatically trade energy costs for space costs, and introduces many powerful control logic operators including protected conditional, general conditional, protected loops, and general loops. In this paper, we present the design and compiler for the three language levels of Eel along with an interpreter to simulate and annotate incurred energy costs of a program.

cs.PL↗