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CITP Seminar: Pramod Viswanath – Witness Chain: Proofs of Bandwidth for Trust-Free Wireless Networking

Tuesday, September 27, 2022
12:30 pm - 1:30 pm


306 Sherrerd Hall
Photo Pramod Viswanath

Video available here.

Open decentralized networking is a decades-old dream, the fabric enabling open, uncensored, global communication. Although this dream drove the design of the original Internet (web 1.0), technological, authoritarian and economic forces have combined to substantially centralize today’s communication infrastructure (web 2.0). The advent of blockchains, trust-free platforms driven by tokenized incentive mechanisms (web 3.0), is reawakening the old dream of open networking and is aided by the tailwinds of inexpensive hardware and cloud computing and lightly regulated spectrum.

A distinguishing feature of a decentralized network is incentives that reward the level of participation, setting up a “hotspot”, providing backhaul and network connectivity, replacing the traditional centralized reputation of the network. A “network meritocracy”, where anyone can participate in network operation and get rewarded based on their performance, depends crucially on trust-free telemetry, a “proof of bandwidth” system, a new scientific discipline at the intersection of applied cryptography, interactive protocols and networking.

In this talk we showcase two proofs of bandwidths: the first, Proof of Backhaul, is a trust-free speed test where the challengers neither need to be trusted or even have a low latency and high throughput connection to the challenged link. The protocol is a reincarnation of classical Internet telemetry tools of ping and iperf with Byzantine fault tolerant properties. The second, Proof of Service, enables trust-free measurement of network service quality (data, throughput) between a pair of links. Both protocols are naturally implemented via smart contracts and scalable state channels, two essential web 3.0 primitives.


Pramod Viswanath recently joined Princeton as the Forrest G. Hamrick Professor in Engineering in the Electrical and Computer Engineering department. He received his Ph.D.  in electrical engineering and computer science from University of California at Berkeley. He was a member of the research staff at Flarion Technologies and a faculty member at the University of Illinois at Urbana Champaign in Electrical and Computer Engineering.

His current research interests are in blockchains. He is a co-founder of Kaleidoscope Blockchain Inc.