Proof of Elapsed Time (PoET) in Blockchain

Proof of Elapsed Time in blockchain uses a time-lottery-based consensus mechanism, distributing wait time to each participating node in the network. Let's understand more!

In this series covering consensus mechanisms used by blockchain networks, today, we picked up Proof of Elapsed time (PoET). It is the algorithm behind the Hyperledger permissioned blockchain network for businesses. 

This article covers the gore details of the PoET algorithm and its functioning. It also covers the difference between Proof of Work and Proof of Elapsed Time. In addition, the article goes through the benefits and limitations of the PoET consensus algorithm.

Table of Content

• What is Proof of Elapsed Time (PoET)?
• How does the Proof of Elapsed Time (PoET) Algorithm work?
• Proof of Work (PoW) VS Proof of Elapsed Time (PoET)
• Benefits of Proof of Elapsed Time (PoET)
• Limitations of Proof of Elapsed Time (PoET)

What is Proof of Elapsed Time (PoET)? 

PoET is a consensus algorithm used in a permissioned blockchain network to decide on mining rights and the next block miner. FYI, a permissioned blockchain network requires participants to prove their identity and whether they are allowed to join. Hence, it needs permission (or invitation) to join the decentralized network as a new participant ( or node).

The PoET algorithm was developed by Intel Corporation, the processor chip giant, in early 2016. Intel associated with the Linux Foundation in the development of Hyperledger Sawtooth. They aimed to build a highly scalable private blockchain network.  

PoET Mechanism assigns an amount of time to each node in the network randomly. The node must sleep or do another task for that random wait time. Whichever node gets the shortest waiting time wakes up and add their block to the network. Later, the new update information floods among other network participants.

The Proof of Elapsed time in blockchain needs to ensure 3 significant factors for this process to work:

• Ensure that the node or network participant gets the random waiting time.
• Check if they are not choosing the shortest waiting time on purpose.
• Verify if the node has completed the given waiting time or not.

Let’s dig a bit deeper into working on the Proof of Elapsed Time mechanism.

How does the Proof of Elapsed Time (PoET) Algorithm work?

The time-lottery concept allows everyone in the network an equal chance of winning the reward and being able to forge a new block to the network. The PoET controller maintains a stopwatch for each participating node. It ensures their waiting time ends, and now they can forge a new block. When the node wakes up, it submits the block and a cryptographic test to the PoET controller for verification. 

A newly proposed block is selected if the controller approves the newly proposed block by the first woken-up node. Otherwise, it gets discarded. And then, the selection process of assigning waiting time starts again.

Let’s break down the process more accurately into steps.

Selection Process

• First, each participating node has to share its certificate by Intel Software Guard Extension (SGX), which ensures its validity to generate a new block in the network. After that, they are eligible to get a timer object.
• The numbers are assigned to each node as a timer object (waiting countdown time) by Intel’s random number generation instruction, RAND. It generates difficult-to-detect random numbers.
• Now, the time object given to each participating node activates.

Generation Process

• After the time object ends and the node wakes up, it’s eligible to forge a new block to the network.
• The active node generates the hash (using a hash function like SHA-256) of its block of transactions and submits it for acceptance. It doesn’t require showing computation work done by the node.
• Afterwards, the update gets flooded to the network.

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

Proof of Work (PoW) VS Proof of Elapsed Time (PoET)

Proof of Work (PoW) demands computation work from nodes (or miners) to become eligible for adding a new block. On the other hand, PoET randomly selects the among participating nodes by distributing waiting time objects. Here, each node is equally eligible to mine a new block.

PoET is way more time and energy-efficient than PoW. It is backed by one of the renowned technology giants, Intel corporation, which makes it more trusting and reliable. 

Benefits of Proof of Elapsed Time (PoET)

Following are the advantages of the PoET consensus mechanism:

• PoET can go up to a million transactions per second.
• It is highly energy-efficient and easily scalable.
• It’s a block generation consensus algorithm, unlike proof of stake (PoS).
• PoET is for privately controlled spaces like business organizations.
• It ensures the same opportunity for network participants with time object and activation.
• As it’s a permissioned blockchain network, the process of selecting validators ensures network security against cyber attacks.

Limitations of Proof of Elapsed Time (PoET)

The following are the disadvantages of the PoET consensus mechanism:

• PoET is a permissioned and closed network, unlike Bitcoin and Ethereum.
• The mechanism highly depends on tools by Intel technology which might raise compatibility issues with other tools later. 

You can also read about Digital Signing in Blockchain using Cryptography.

Conclusion

The above article covered the PoET algorithm and its working. It also compares the difference between Proof of Work (PoW) and Proof of Elapsed Time (PoET). Moreover, it adds to the benefits and limitations of the PoET consensus algorithm.