Mimblewimble in blockchain, at what price?

by Lumai Mubanga

In plain language, mimblewimble refers to the tongue-tying curse that binds the target’s tongue to keep them from talking about a specific topic or subject. In short, it is a term to define some level of privacy that need to be kept.

In blockchain terms, it defines some level of anonymity with an assurance to improving privacy in bitcoin. In this article, we consider a few characteristics of mimblewimble in blockchain and then analyses if it is a better protocol and the price you pay for its implementation.

It all started with a user with the pseudonym who wrote the proposal called Mimblewimble with specific reference to a curse that was used to keep people from talking about a specific subject. The MimbleWimble proposal proposed a design for a blockchain-based ledger system that used a cryptographic protocol more scalable and private than that of Bitcoin.

In order to remain a low functionality protocol, MimbleWimble aims to modify transaction types in Bitcoin. This design will allow it to be an as low-functionality as possible on one hand, while maintaining high-privacy and high-scalability on the other. This sleek change in the design will make it different from normal bitcoin. As such, it can be implemented as an alternative blockchain. Alternatively, it may also be implemented as a side chain or as an altcoin of some kind that could support a different type of transaction than what Bitcoin uses currently. The following features are prominent:

Cryptographic Primitives

On the privacy side, MimbleWimble is deliberately built on what is referred to as cryptographic primitives. These include range proofs, homomorphic commitments and Pedersen commitments among others. These are infused to enhance the privacy side of the protocol.

Blinding Factors

Blinding factors are powerful cryptographic functions that “blinds” transaction details in a smart way were all values in a transaction are encrypted with so called “blinding factors”. Additionally, secondary elliptic curves are used solely for privacy’s sake. This explains why MimbleWimble based coins provides an alternative but scalable option to bitcoins. The features of cryptographic primitives have enhanced its capabilities that sets it apart from normal bitcoins.

Larger transaction Blocks

The MimbleWimble design also bundles many transactions into larger transactions. This is done to scramble inputs and outputs, which obscure the source and destination of Bitcoins. This ensures that each block is treated as one large transaction. This too allows for blocks merging across many transacting blocks.  Joining transactions across blocks could extend all the way from the starting block to the latest block. One advantage of doing this is that it results in a reduction on the need to maintain entire blockchain history as Mimblewimble promises to half the size of the blockchain. But what could be the possible draw back?

From about 2016, close to 150 million transactions had to be replayed to produce a set of only 4 million unspent transaction outputs. Mimblewimble promises to half the size of the blockchain: while still maintaining confidential transactions and obscured transaction graphs. And that’s the price one must pay to enable such privacy that Mimblewimble promises to provide.