Blockchain and Multi-Party Computation: The perfect match for secure data collaboration

At Partisia, we’re solving this challenge with our platform built on two core technologies: Multi-Party Computation and blockchain. 

Together, these technologies solve a critical challenge:

How can multiple parties run calculations on private and sensitive data securely without any single party controlling the process and keeping the real values of the data completely safe?

But why is it that these two technologies make such a powerful match? In this blog post, we’ll explore what each technology contributes with and how they complement each other to form the ultimate privacy-preserving solution.

Multi-Party Computation (MPC): The privacy protector
MPC lets multiple parties compute a shared result without ever revealing their individual data inputs to one another. Each participant keeps its own information secret. This makes MPC a powerful protector of privacy, ensuring that no participant ever sees anyone else’s raw data.

Blockchain: The orchestrator of MPC
A blockchain is a distributed, unchangeable ledger that allows a network of computers to agree on what to do and when. Because it’s decentralized and transparent, everyone sees the same ledger and no one can secretly change it. This makes blockchain an ideal technology to make the magic of MPC happen.

Both technologies complement one another: blockchain orchestrates Multi-Party Computation (MPC), while MPC brings privacy enhancements to the blockchain. In the next section, we’ll explore exactly how this two-way synergy works.

When you run an MPC calculation, you have two or more computers working together to reach a final result. That creates some tricky challenges:

• How do the computers agree on what math to do?

• How do the computers know when to start and what rules to follow? 

• How do we prevent someone from acting maliciously by actively changing the values they should be sending to other MPC nodes to mess with the other participants?
  

MPC needs a reliable way to make sure everyone is on the same page and follows the exact same instructions. For example, knowing what to calculate, when to start, and which version of the code to use.

We know Multi-Party Computation (MPC) keeps each party’s data private, but for MPC to work smoothly, the technology needs some kind of coordination. That’s where blockchain comes into play, acting as a decentralized, transparent, and secure layer that coordinates the steps in the entire process. 

Let’s look at why blockchain is so effective at orchestrating MPC by addressing the challenges we raised in the last section.

• How do the computers agree on what math to do?

Blockchain uses a consensus system, so every computer is on the same page: they follow the same instructions and code. No one can secretly change them behind the scenes.

• How do the computers know when to start and what rules to follow? 

Blockchain supports smart contracts, which are like automatic rule enforcers. These are contracts where everyone agrees on the rules, like when a calculation should begin, who takes part, and what happens to the results. Because they run automatically once conditions are met, there’s no need for anyone to manually oversee the process. This ensures everyone follows the same rules from start to finish.

• How do we prevent someone from acting maliciously by actively changing the values they should be sending to other MPC nodes to mess with the other participants? 

With blockchain, we get permanent, unchangeable records. Each step of the MPC calculation (when it starts, who’s involved, and how it ends) is  documented on the blockchain. These records can’t be altered later, so there will always be a transparent audit trial. 

That means if one person tries to act maliciously or disrupt the process, it’s possible to track what has been agreed on and in which order things have happened. That way, it will always be possible to pinpoint if there is an evil party in the network.

Blockchain is excellent at orchestrating Multi-Party Computation (MPC), but the other way around, MPC is also solving some privacy problems on the blockchain. 

A big disadvantage of blockchain is the lack of privacy. It’s a decentralized world where everyone has access to all data on the network. Now, if you want to introduce something secret (like personal data that must be protected to avoid breaking privacy laws), everyone will be able to see it on the blockchain. 

Before jumping into how Multi-Party Computation enhances privacy on blockchain networks, it's worth talking about different types of blockchains and the level of privacy they provide.

Let’s start with a quick comparison between public and private blockchains.

Public blockchain
A public blockchain is open for anyone to join, and all transactions are fully visible to every participant. This setup provides a high level of transparency, but it may not be ideal when you’re working with confidential or private data that needs to remain secret.

Private (permissioned) blockchain
A private blockchain is permission-based, so it restricts access to authorized parties only. 

The network administrator controls who can join and often defines each participant's access rights, or the network can be vote based, so the organisations running the network collectively serve as the network administrator.

Though a private (permissioned) blockchain lets you choose who can join the network, anything stored on it is still visible to all participants within that network. On a public blockchain, transparency is even greater, since anyone can see all transactions. 

Either way, if you need to keep data secret, even from other participants, a blockchain on its own, whether public or private, isn’t enough.

That’s where Multi-Party Computation (MPC) comes in. MPC allows two or more parties to calculate a result from their combined data without revealing the individual inputs. Instead of storing sensitive information in clear text on the blockchain, where it can be seen by everyone with access, you only ever reveal the final output or choose the parties you want to reveal it to.

Wrapping up, we’ve explored how Multi-Party Computation (MPC) and blockchain complement each other. MPC guarantees privacy and data security while blockchain helps orchestrate the whole thing by ensuring transparency and coordination.

This powerful synergy allows companies to perform secure and private calculations on sensitive data, even when collaborating on joint datasets. A game-changer for industries looking to open new doors with data-driven insights – with MPC blockchain and MPC leading the way!

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