Before Blockchains, There Was State Machine Replication
7/13/202637 min
Every blockchain today relies on replication techniques first developed in the 1980s by researchers who weren't thinking about cryptocurrencies at all.
In this episode, Tim Roughgarden speaks with MIT professor and Turing Award winner Barbara Liskov, one of the pioneers of programming languages, fault tolerance, and distributed systems. Joined by a16z crypto research partner Ittai Abraham, they trace the evolution of ideas that now underpin modern blockchain networks.
The conversation explores viewstamped replication, Practical Byzantine Fault Tolerance (PBFT), state machine replication, and why concepts developed decades before Bitcoin became the foundation for today's blockchain protocols. Along the way, Liskov reflects on the relationship between theory and practice, the importance of modularity and formal reasoning, and why AI is creating a new generation of systems research.
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Clips
Transcript preview
First 90 secondsBarbara Liskov· Guest0:00
[upbeat music] DARPA had recognized that this was a serious problem, the problem of malicious attacks, and was looking for research in that area. I had a student, Miguel Castro, he came to me and he said, "Why don't we see whether we can figure out a way to do replication that handles these malicious attacks?" And that seemed like a great idea. The problem, if the primary failed, the primary that was running the protocol, the whole thing came to a crashing halt. We came up with a protocol that if the primary seemed to not be doing its job, the backups then carried out another protocol in which a different replica became the primary. We thought that at some point people would start to use this, and then along came blockchains. [laughs] And so that was very shocking.
Tim Roughgarden· Host0:45
Someone who loves computer science, loves research, wants to do important work, wants to have an impact, what would you suggest as kind of a mindset, as an approach?
Barbara Liskov· Guest0:53
Computer science is in a very strange place right now with the advent of AI. I think that as far as research is concerned- As part of our Summer Feed Drop series, we're sharing another episode from the a16z Crypto Show.
Speaker 31:07
Every blockchain today relies on replication techniques first developed in the nineteen eighties, years before anyone imagined cryptocurrencies. In this episode, Tim Roughgarden and Itai Abraham speak with Turing Award winner Barbara Liskov, whose pioneering work on distributed systems, state machine replication, and practical Byzantine fault tolerance laid the foundation