Can Mimblewimble deliver on the promises of large-scale privacy and scalability for blockchains?

In a recent Q&A, Andreas Antonopoulos gave his thoughts on the potential of the Mimblewimble technology and its two current live implementations in Grin and Beam.

The open blockchain technology Mimblewimble was first proposed by an anonymous developer in a white paper back in 2016.

The author of Mastering Bitcoin said that at a very basic level, this type of blockchain uses some very interesting tricks with public/private key cryptography to aggregate and summarise the intermediate states between transactions in a blockchain. By using this approach, any implementation can massively optimise data requirements whilst also delivering increased privacy to its users.

Privacy that doesn’t hinder scalability 

In the Q&A, Andreas Antonopoulos said that Mimblewimble represents “a really interesting solution to an important trade-off [in blockchains] where privacy came at the cost of scalability.”

The Mastering Ethereum author said that for many previous attempts at high privacy in blockchains such as zero-knowledge proofs (like zk-SNARKs or confidential transactions), the transactions are private but their transaction size can become very big. Examples of such sizes range from 200 bytes without privacy all the way to 20 kilobytes for a private transaction on the same blockchain.

He went on to say that “a lot of cryptographers and computer scientists have found ways to introduce privacy, but the trade-off has always been that it takes an enormous amount of data in order to do so.”

“So far, the practical private blockchains have all been breakthroughs that reduced the scale impact.”

However, with Mimblewimble, “you can discard some of the intermediate states. This massively compresses the [size of the] blockchain. This is the first time we have a situation where privacy and scaling are both optimised at the same time.”

Grin and Beam

The first effort to implement Mimblewimble, which started two years ago, is an open source community project called Grin.

Antonopoulos noted that Grin is open source and crowdfunded, stating: “It has no pre-mine, no initial coin offering (ICO), no financial model to support development other than dedicated volunteers within the community.”

Beam was launched a year later with a different model. Beam has a foundation (similar to Zcash) and a project treasury that has received venture capital investment. The project also has an organisation that funds development of the Beam protocol.

“They have two different approaches to governance: Grin is a very grassroots, community development model that is mostly research focused. Beam, on the other hand, is more commercially oriented, with the goal of creating viable commercial products.”

Different monetary models

Antonopoulos concluded that both Grin and Beam have interesting differences in their monetary models.

“As far as I understand it, Grin issues 60 new coins per minute in a linear and continuous issuance schedule. Beam’s monetary policy is more similar to Bitcoin, with a fixed supply where issuance stops (after 133 years).”

“Grin is intended to be a medium of exchange, and Beam is intended to be for store of value. How will they play out? I will not say which one is better or worse, but these projects are very complementary.”

“In many cases, they are collaborating. They are trying to advance the state of the art in this particular area.”