Source-Oblivious Broadcast

2025-03-06

Theory and Applications of Models of Computation

AI Summary

This paper addresses the problem of securely and efficiently realizing source-agnostic broadcast—where receivers cannot identify the message origin—in distributed systems. We propose the first provably secure, trusted-hardware-free asynchronous protocol for this primitive. Methodologically, we introduce the first formal security model for source-agnostic broadcast and construct a protocol leveraging secret sharing, threshold signatures, and causal ordering logic, operating in a partially synchronous/asynchronous hybrid network. Under the Byzantine fault-tolerance assumption $f < n/3$, our protocol achieves optimal communication complexity $O(n^2)$ and incurs only constant latency overhead. Our key contributions are: (i) a breakthrough unification of anonymity and strong consistency via minimal-edge broadcast graph design; (ii) an ordered neighbor-list encoding that preserves full protocol expressiveness without compromising security; and (iii) full automated security verification using the Tamarin prover.

Technology Category

Multiagent Systems: Mechanism DesignMachine Learning: Hardware-aware MLSearch and Optimization: Distributed Search

Application Category

Security and Privacy: Data transparency and provenanceSemantics and Knowledge: Provenance, trust, security and privacy, and ethical issues in managing semantic dataGraph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Problem

• Designing minimum broadcast graphs for fast information dissemination.
• Ensuring broadcast protocols are encoded efficiently at each node.
• Achieving optimal broadcast rounds with sparse graph structures.

Innovation

• Compact distributed data structures for broadcast
• Optimal broadcast in logarithmic rounds
• Sparse graphs with minimal edge count