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Proof of Elapsed Time( PoET) in Blockchain

Proof of Elapsed Time (PoET) is a network consensus algorithm that prevents high resource utilization and energy consumption. It implements a fair lottery system to keep the process more efficient. 

What is Proof of Elapsed Time( PoET)?

Blockchain technology is a distributed ledger used to record any transactions that happen over the network and since Bitcoin’s inception and the introduction of the Proof of Work (PoW) consensus model as the mechanism for a blockchain network’s legitimacy. After numerous other consensus mechanisms have been experimented with and introduced, the Proof of Elapsed Time (PoET) concept is one such mechanism which was invented in early 2016 by Intel Corporation and is one of the fairest blockchain consensus algorithms that enables permissioned blockchain networks to determine who creates the next block. 

Intel in collaboration with other organizations such as the Linux Project and IBM sponsored the Hyperledger Sawtooth project, this open-source project uses the PoET consensus mechanism. Hyperledger Sawtooth is a distributed ledger that is both scalable and adaptable for many uses at the enterprise like supply chain and logistics. This mechanism is based on Byzantine Fault Tolerance and aims to reduce the energy consumption associated with proof of work’s mining process.

3 Factors Need to Be in Favor for PoEt to Work:

  1. Ensure that the node gets the random waiting time instead.
  2. Check if the nodes are not choosing the shortest wait time on purpose.
  3. Verify if a node has completed the given waiting time or not.

Proof of Elapsed Time

How Does PoET Work?

The PoET mechanism replaces the need for mining intensive rights required in Proof of Work with a randomized timer system. The PoET consensus mechanism distributes the chances of winning across the largest possible number of network participants and every node is likely to be selected by a fair lottery system. 

In this consensus mechanism the problem is ” how to determine the leader of a round of consensus” and whoever solves the computationally intensive cryptographic puzzle of each block round is selected as the leader for the round. For the node to participate in consensus, it downloads the trusted code which requires code attestation by Intel Software Guard Extension (SGX). SGX functions as a Trusted Execution Environment (TEE), which allows selecting, trusted code to run independently of the application that it runs in.

The PoET consensus mechanism is divided into 2 phases:

1. Selection Process: This process involves the following activities:

2. Generation Process: This process involves the following activities:

Therefore, this ends the iteration of mining a new block in a permissioned blockchain network using the PoET consensus algorithm.

Proof of Elapsed Time( PoET) vs Proof of Work (PoW):

Unlike the proof of work (PoW) algorithm, Proof of Elapsed Time( PoET) requires less power consumption, also it allows a node to sleep and switch to other tasks for the specified time, thereby increasing the network’s efficiency in terms of power and time. The PoW mechanism provides a competitive work environment, whereas the PoET mechanism provides a random selection environment.

The below table summarizes the difference between PoET and PoW:

Parameters PoET PoW
Blockchain type Permissioned Permissionless
Transaction rate Medium Low
Token needed No Yes
Energy efficiency More energy efficient. Less energy efficient.
Power Consumption Less power consumption. More power consumption.
Network Efficiency Increased network efficiency. Less efficient network.
Environment It provides a random selection environment. It provides a competitive work environment.

Benefits of PoET:

Limitations of PoET:


PoET is highly efficient and works with SGX which is an emerging technology and future developments surrounding SGX will have a major impact on PoET as a sustainable consensus model. PoET represents another breakthrough in providing Byzantine Fault Tolerance consensus mechanisms for distributed ledger systems.

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