What is PoA (Proof of Authority)?

1 April 2019

Medium min reading

What is PoA Proof of Authority or proof of authority, meaning of PoA, which means proof of authority, proof of authority in Spanish, which means proof of authority, bitcoin poa, consensus cryptocurrencies poa

PoA, is the acronym for Proof of Authority, a new consensus protocol used in blockchain. Its name in Spanish means, Proof of Authority. This new consensus protocol is based on the reputation of elected representatives who participate in a blockchain.

LProof of Authority, it is designed to be a practical and efficient solution, especially aimed at private blockchains. The term of POA was proposed by Gavin Wood, co-founder and ex-CTO of Ethereum. This consensus protocol has a marked difference to others such as PoW y PoS. This is because PoA takes advantage of real identities to allow validation within a blockchain. This means that validators put their real identity and reputation as a guarantee of transparency.. A process that includes, a selection arbitrary of such trusted validators. A totally different situation from PoW mining, but with similarities to the scheme of PoS participation.

Furthermore, PoA is based on a limited number of validators. This feature gives it a clear advantage, the high scalability of the blockchain. What has a positive impact in applications where speed is paramount. In addition, it maintains a high level of access control to said blockchain, since only nodes with permission can participate.

How does the PoA protocol work?

The operation of the PoA protocol is quite simple. First, for the system to work, validators must be chosen at random. The inclusion and selection of nodes. it is done thanks to a voting system of other nodes previously authorized. In this way, it is avoided that malicious nodes can be included and affect the operation of the network. In addition to this, each validator can sign a maximum of one of a series of consecutive blocks during their validation turn. Additionally, PoA does not require a mining is. as it happens in Bitcoin, so it is very eco-friendly.

As in PoS, where participation is used as a measure of selection and trust within the network, PoA makes use of identity and reputation. The identity of a person or institution is scarce, and its reputation is very valuable. Its use within the protocol means, that the validator must disclose who he is voluntarily. By making this information public, it is easy to establish responsibilities in the operation of the blockchain. Any act that threatens the reliability and transparency of the network falls directly on that person or institution. Something that can undermine or destroy your reputation everywhere.

In this way, the validators of a blockchain using the PoA protocol will take care of its reputation and identity. And it is for that reason, that they will ensure the proper functioning, transparency and reliability of its operation. In this sense, the identity put into play can serve as a great equalizer, understood and valued by all actors. People or institutions whose identity is at stake will feel encouraged to preserve the network.

PoA operating conditions

The PoA operating conditions are the necessary steps for protocol compliance. Among them, we can highlight the following:

Necessary validate the identities of potential validators. This means that those who want to participate in the network must verify and make their real identities public.
El candidate a validator must be ready a invest money and put su reputation as guarantee. This process guarantees that the candidates have motivations to participate in long term within the network.
You must have a work standard to la approval of a validator. With this, it is sought that the selection method is appropriate to select equally the candidates for validators.

The system must be able de delete a possible malicious actors. If a validator within the network acts badly, the network must remove it. All this in order to maintain the trust and transparency of the rest of the parts of the network.

PoA protocol limitations

Centralization

One of the PoA's most criticized points, es que his model renounces the scheme of decentralization and distribution. In fact, the protocol is designed for a distributed centralization, where there are few who participate in the network. What makes it perfect for private blockchains where they seek a high level of security and scalability in them.

Public Identities

Another common criticism is that the identities of PoA validators must be public. A situation that many see as worrisome, since it leaves those who participate in the blockchain exposed. This could lead to manipulations by third parties, who want to take advantage of any weakness of that person or company that acts as a validator.

Objectionable

Other specialists add that the PoA protocol greatly facilitates censorship and blocking through blacklists. On the one hand, this is positive for private implementations such as those that could be carried out by banks. On the other, it rejects the uncensorable nature of blockchain networks.

Vulnerable

It can also happen that a malicious user is added to the list of signers, or that a key / machine is compromised. In such a scenario, the protocol must be able to defend itself against reorganizations and spamming. To avoid this, there is a limitation that validators can only sign a single block of a set of it. This limits the damage that an attacker can do.

Overflow

Another limitation of the system is that the signatories can inject new voting proposals within each block they validate. This is because the nodes need to count all the votes to create the list of authorized validating nodes. The purpose of this is to track all the votes over time. and control them.

PoA protocol implementations

As mentioned above, PoA consensus is used in the test network Hive y Rinkeby de Ethereum. It is also used by several well-known platforms and, from this point on, it seems to be the most plausible consensus mechanism for institutions seeking to implement private blockchain networks.

The best known of these networks is POA Network. A public network for smart contracts that works like a sidechain from Ethereum. In it all its nodes are formed by independent validators. They use the database of notaries public as a mechanism for the eligibility of validators. Essentially, validators go through a formal identity verification using two steps. A client who makes use of the software POA Network DApp, as well as the notary public system.

Hyperledger y Ripple They also make use of the PoA protocol on their blockchain. In the case of Hyperledger Fabric is based on the Byzantine Fault Tolerance, but uses the PoA consensus as part of its overall open source framework for the consortium's blockchains. Ripple It uses an iterative form of PoA consensus and more detailed information about its consensus process can be found here.

Another chain that uses PoA is VeChain. This is an enterprise level public blockchain specialized in transparent management of business information. Focused especially on the management of the supply chain and logistics.

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Author

Jose Segura

Engineering Department Coordinator

José Segura works as a problem solver in Bit2Me's IT team, where he started as Lead Engineering Manager and currently coordinates the entire department.