What is Proof of Replication in Crypto?

Blockchain technology isn’t understood very well by many, and many of its mechanisms are undeniably complex. Consensus mechanisms are one example of these, although figuring out algorithms such as proof of replication (PoRep) helps judge the worth of a certain crypto.

Proof of replication isn’t the most common consensus mechanism, with that crown being shared by the “OG” proof of work and proof of stake. In fact, PoRep is unique to Filecoin, a decentralized, blockchain-based data storage platform.

Before looking at proof of replication in detail and how it works, we need to first explore what consensus algorithms and proofs are and why they’re so important. Let’s get straight to it!

What are Consensus Algorithms?

Each “block” in a blockchain is made up of a group of transactions that are performed on the network within a given period of time. When you send coins to someone else on a blockchain, that’s a transaction, and the details of it and others like it are recorded and published to the ledger.

This duty of recording and publishing transactions is done by certain network nodes. You may know them as “miners” on proof-of-work blockchains such as Bitcoin or as “validators” on proof-of-stake chains like Ethereum.

These nodes are independent and can be located anywhere in the world. The idea is that a blockchain is upheld by lots of smaller, distributed entities rather than a handful or even a single centralized one.

This ability of the network as a whole to agree on what transactions should make up a block is called “consensus.” Regarding distributed systems, consensus has been spoken of for a long time, and it’s a central concept of blockchain.

Without a centralized arbiter, who’s to say whether your transactions are valid or not? Hence the need for a mechanism to ensure this sort of decentralized consensus.

Bitcoin’s proof of work is likely the best-known consensus mechanism, and it’s certainly the oldest. Most early blockchain projects followed in Bitcoin’s footsteps with forked or modified proof of work models, but the scope has begun to broaden in recent years.

In addition to the extremely widespread proof of stake consensus that’s common to most newer blockchains, there are also systems like proof of authority, proof of history, and proof of burn. But what is proof of replication?

What is Filecoin’s Proof of Replication?

Proof of replication is a system used by the Filecoin network, and it’s a little different from the norm because Filecoin itself doesn’t fit the cookie-cutter blockchain mold of payment systems or smart contract platforms.

Rather, Filecoin is designed to be a blockchain-based, decentralized digital storage and data retrieval method.This may not sound particularly romantic on the surface, but it’s actually a rather important mandate.

You see, the modern world revolves around data. The internet itself could be considered nothing more than a vast repository of data, which we all interact with on an unhealthily frequent basis.

And, as the world increasingly revolves around a core of data, a handful of megacorporations have been able to wrest monopolistic power over the hosting of all of this data.

Amazon, according to the media arm of the Motley Fool financial group, would not be profitable without Amazon Web Services. Worryingly, many blockchain-based workloads also utilize AWS, which is a huge centralization risk.

Filecoin attempts to solve the major issue by providing a decentralized storage network that turns cloud storage into a blockchain-based algorithmic market. Storage providers, known as storage miners, are matched up with clients, and the FIL token is used to set up storage contracts.

The “proof” that a system like Filecoin requires, therefore, is proof that storage miners have actually stored the data that they’re being paid. This is what proof of replication accomplishes.

How Does Proof of Replication Work?

In Filecoin, units of data are stored in sectors. Specific data is “sealed” in a sector on disk, encoded, and then proof of this is committed to the blockchain. Sealing is similar to the proof of work in that it requires an intense amount of work to be spent on that particular proof.

Proof of replication combines elements of both proof of storage and proof of space. Proof of storage is a simple system to prove that a party is in possession of some data, and proof of space guarantees that the party is spending a certain amount of storage.

What this means is that clients can be assured that the exact data that they want stored is actually being stored and that nothing else is taking up the storage space that they’re paying for. The data can also be retrieved easily, and Filecoin uses SNARKs to prove some of the actual PoReps when large outputs are produced.

These proofs are instant, so Filecoin adds the element of time by incorporating proof of spacetime to ensure the storage of data for the current amount of time. The addition of proof of spacetime results in storage miners being asked for PoReps for random sectors that they can only answer by consulting those sectors directly.

They have to respond to these challenges every day and fulfill certain time limits. Thanks to this mechanism working on top of PoReps, Filecoin is able to provide a proof system that ticks all the boxes.

According to the proof of replication whitepaper released by Filecoin founders Protocol Labs in 2017, the proof of replication protocol can also be chained to establish useful proofs of spacetime (PoSt). PoSt lets a verifier check if a prover is storing their data for a certain period of time.

Proof of replication is extremely useful for cloud computing and decentralized storage networks like Filecoin, given that it allows transparent verification of data being replicated to its own uniquely dedicated physical storage.

Other Related Proof Variants

Neither Filecoin nor its proof of replication system are completely unique in their aims, so let's take a look at some of the other related proofs in this domain:

#1. Provable Data Possession

These provable data possession (PDP) schemes allow users to send data to a server and later check whether the server still stores the data. They can be privately or publicly verifiable, and various configurations of PDPs exist.

#2. Proof of Retrievability

PoRet is similar to PDP, with the added fact that stored data can also be retrieved. In a PDP, this feature of retrievability is not necessarily present, with the server needing only to prove that the data is held and releasing it being optional.

Proof of retrievability is a solution to the problem, making the proofs leak parts of the data so that it can be reconstructed after a certain number of proofs are released.

#3. Proof of Storage

A proof of storage scheme (also called PoS, but not to be confused with proof of stake) lets a user store data on a server and then check if it’s still being stored. It’s an older system and generalizes both PDPs and PoRets.

#4. Proof of Space

PoSpace allows a prover to convince a verifier that they have spent a certain number of storage resources. PoSpace is essentially a proof of work system where the “work” isn’t computation but storage space instead.

#5. Proof of Spacetime

PoSt lets a prover convince a verifier that they’ve spent some “spacetime,” or storage space used over a period of time. It takes the PoSpace scheme and introduces checking over time.

Proof of Replication vs. Proof of Work

Proof of work is the original consensus mechanism used in blockchains, and it is crucial for many cryptocurrencies, including Bitcoin. PoW provides proof to the network that resources have been spent, and in many blockchains, that resource is computation.

There’s an element of PoW when it comes to the proof of space aspect of PoRep, in that proof of replication does involve proof that certain data is being stored. As mentioned previously, the process of sealing involved in Filecoin’s proof of replication is akin to work performed by the system.

That being said, PoRep is a system that’s comparable to a real-world physical storage provider. If you were to rent out a certain amount of space in a warehouse to store something of yours, you would expect three things:

• To see that the warehouse is storing your belongings
• To see that the warehouse is only storing your belongings and not using the space you pay for to store anything else
• To be able to retrieve your belongings when you want them back

This is what proof of replication, as deployed by its creators, does for the Filecoin protocol.

Proof of Replication Benefits

With so many proofs available for storage schemes, proof of replication has to offer a significant number of benefits to be worthwhile. Here are some of them:

• Decentralization. Data centralization is a concerning issue as far as the current state of the world wide web goes, and systems like proof of replication are ideally suited for decentralized competitors to provide safer, more trustworthy options than the existing Web2 alternatives.
• Verifiable. In a decentralized system, independent verification is paramount. PoRep allows storage to be both publicly and privately verified, removing the need for a centralized arbiter.
• Retrievable. This eliminates the problem of data being held hostage by actors in pure proof of storage systems, with PoRep ensuring that the client can retrieve the data whenever required.
• Useful. One of the major criticisms of proof of work systems is that the computational proof system used is a waste of resources. PoReps, on the other hand, do not waste any effort, with all work done being directly useful in proving storage.

Proof of Replication Drawbacks

Despite the many benefits of proof of replication for decentralized data storage networks, critics often point to one key disadvantage: bandwidth.

When a new node is added to the redundancy pool, the replicated data must be transferred each and every time. This system naturally drains network bandwidth.

Future of Proof of Replication

Given its value to systems like Filecoin, it could be argued that proof of replication is here to stay. It offers several key benefits and incorporates some of the best features of similar proofs, solving many, if not most, of the problems faced by these systems.

Despite that, proof of replication remains a technology, a solution to a problem. On the other hand, the protocols or systems that use it are set against some of the biggest tech behemoths today.

Filecoin and similar projects are facing off against trillion-dollar firms in the next-generation battleground of data, and while they aren’t without hope, the deck definitely seems stacked against them.

Key Takeaways

Proof of replication is a system used by Filecoin to provide users with proof that their data is being stored in dedicated, unique physical storage without the risk of deduplication.

PoRep is a revolutionary addition to the proofs available for cloud storage and decentralized storage networks. Since a proper level of replication is important to these protocols, and rational servers may create Sybil identities and sell their service twice to the same user, PoRep offers plenty of protection.

You won’t see PoRep in many projects, but part of the reason is that there aren’t more than a handful of blockchain firms targeting decentralized data storage in any case. Among those that do, however, PoRep definitely has its place.