"And then along came blockchains." Turing Award winner Barbara Liskov on how PBFT — practical Byzantine fault tolerance, now foundational to modern consensus — started as a PhD student answering a DARPA RFP: "I had a student, Miguel Castro, who was looking for a PhD thesis, and I suggested to Miguel that he look at the RFPs that DARPA had put out … He found an RFP that was looking for ways to handle the malicious attacks that were going on on the internet." "When Miguel and I finished the work on practical Byzantine fault tolerance, we thought that at some point people would start to use this. … It was a delay of about 10 years before people started to use it."