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I was looking at consensus mechanisms other than the common PoW and PoS, and found a scheme known as proof of elapsed time.

I am struggling to find any research or proofs to show that this is in fact a Byzantine Fault Tolerant algorithm.

Dan Anderson
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BOB
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2 Answers2

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There is more info in this Hyperledger blog post.

In short, if secure hardware is used, it can be BFT. In Hyperledger Sawtooth there are two PoET variants:

  • PoET SGX runs with SGX hardware. It is BFT (assuming the enclave itself has no vulnerability)
  • PoET CFT (also called PoET Simulator Mode) runs without SGX hardware. It is only CFT
Sigmatics
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PoET is BFT because PoET's waiting time is enforced with an SGX enclave.

There is also more defense-in-depth checks, but that doesn't make it BFT. In comparison, Bitcoin's PoW accomplishes the same thing with repeatedly hashing, which is effectively the same thing (although extremely wasteful) as PoET's trusted timer. For details, see the PoET 1.0 spec:

https://sawtooth.hyperledger.org/docs/core/releases/latest/architecture/poet.html

More insights for how PoET works is at the PoET2 RFC: More details and changes are documented in the PoET2 RFC at https://github.com/hyperledger/sawtooth-rfcs/pull/20/files

Dan Anderson
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