Ling Ren's NSF CAREER Award Establishes New Foundations for Blockchains and Distributed Systems

8/2/2022 11:23:05 PM Aaron Seidlitz, Illinois CS

Since he was a PhD student, Illinois Computer Science professor Ling Ren has participated in research focused on computer security and cryptography. That experience has led him to one observation for which he based a successful submission for the NSF CAREER Award on.

Ling Ren
Ling Ren

Ren came to understand that Bitcoin, and its underlying technology – commonly referred to as blockchain – is a “new solution to a classic problem in computer science called the Byzantine fault-tolerant consensus.”

Ren will use the NSF CAREER Award funding - $500,000 over the next five years – to “establish an algorithmic foundation for blockchains that is rooted in decades of research on Byzantine fault-tolerant consensus.”

This, he’s said, helps offset one of two mistakes in the approach of studying Bitcoin and blockchain technology to offer truly groundbreaking results in the area.

“From what I observe, many in the community view the Bitcoin technology with either too much or not enough enthusiasm,” Ren said. “Some think of Bitcoin merely as a new application of classic consensus research. Others think of it as an entirely new concept, and hence study blockchains on its own, paying little attention to its connection to the decades of research on Byzantine fault-tolerant consensus. Both views lead us astray.

“The former leads to a tendency overlooking Bitcoin's new algorithmic ideas, contributions, and inspirations. The latter leads to a tendency to fixate on aspects that may seem groundbreaking at first sight but are not really novel in the lens of classic consensus research.”

His proposal for the CAREER Award – entitled “Algorithms Foundations of Blockchains” – finds the happy medium to then identify the real innovations within blockchains.

Already progressing, after the award officially started in June, Ren has particularly homed in on what he considers to be “one of the most profound open questions in blockchain and fault-tolerant distributed algorithms: What is the right theoretical model for practical fault-tolerant distributed systems?”

What this question really drives at is the capability and security of these protocols in the real world.

“I hope this project will shed some light on this by identifying, formalizing, and improving upon the real innovations of blockchains,” Ren said. “As a first step, my coauthors and I developed a new method to analyze the concrete security of Nakamoto-style blockchains. This method is extremely simple and gives near-exact security for a blockchain using parameters similar to Bitcoin.

“Now, we can finally claim that the security of Bitcoin is backed by solid theory.”

By simplifying the technology, Ren’s work will also lead to one final goal for the NSF CAREER Award: focusing on an educational component that will help K-12 and undergraduate gain understanding of blockchain technologies.

“One problem with existing blockchain analyses is that they are too complicated, involving heavy notations and spanning tens of pages,” Ren said. “This makes them very hard even for experts, let alone beginners, students, developers, and people outside CS and STEM. The new algorithmic analysis is much simpler.

“I can now see myself teaching blockchain with algorithmic rigor to undergraduate students and even high school students.”