Proof of Elapsed Time (PoET)
Background
Developed by Intel in 2016 as an efficient consensus mechanism to be used for permissioned blockchain networks
Fair Lottery System: Each node has the same probability of being chosen
Assists with network performance by putting a node in a resting phase and redirecting it to do other tasks
The code cannot be changed by another participant
Is a random selection mechanism that increases transparency of network consensus
Proof of Elapsed Time: is a proof that a participating node samples a random variable and waits until the amount of time specified by the same has elapsed. Then the participating node with the smallest sample becomes the leader to mine a block to be appended to the chain.
Nodes are forced to stay honest, since all this is taking place in a trusted execution environment (TEE). An example of this is Intel SGX which we will save for a seperate post.
Certificates
Fairness/Honesty: The elapsed time we talked about earlier is not controlled by a node, but rather is generated in a random pattern, thus each node will be given the same random probability of becoming the lead node.
Time: Time plays a big role, since the node will wait for the elapsed time (certificate).
Fundmental: Certificates that are generated in a trusted execution environment (TTE) are protected from nodes that want to behave in a dishonest manner.
Trusted Execution Enviornments
Given the security concerns that surrond Operating Systems (OS), this model of operation becomes prone to attacks due to the weak security model and potential for bugs. Therefore, it is not advised that this model be trusted due to the lack of integrity and trustworthiness.
Trusted Execution Environments are designed for secure remote computation to take place where the owner of the code wants to execute the code on a remote machine that is not verfied or trusted.
SGX provides blockchain support through the “Sawtooth Hyperledger” that implements proof of elapsed time through proof of elapsed time protocol designed for permissioned blockchains.
We will spend time tomorrow looking into the Sawtooth Hyperledger.