Going Deep on Privacy: MimbleWimble (Part 1)

We previously published similar articles on privacy coins Monero and Zcash from this author.

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New Coins on the Block

Grin and Beam are two of the newest privacy coins to come to market. They are both implementations of a proposed design for a new blockchain called MimbleWimble, which has generated significant buzz in the blockchain community due to a) its elegant proposal for a privacy blockchain and b) its bitcoin-esque origin.

MimbleWimble

MimbleWimble’s story begins in August 2016. While the crypto community was focusing their attention on the emergence of Ethereum and the concept of an initial coin offering, an unknown individual going by the pseudonym Tom Elvis Jedusor (Lord Voldemort’s real name in the French Harry Potter) dropped an innocuous text file in a bitcoin IRC (internet relay chat) channel via Tor (The proposed blockchain was named MimbleWimble because that is the name of the tongue-tying spell in Harry Potter, which prevents the target from speaking. It’s the “encryption” spell equivalent in Harry Potter).

Because its ideas were legitimate and actually had the potential to improve upon the status quo of privacy blockchains, the white paper quickly made waves through the blockchain development community. The white paper particularly piqued the interest of Andrew Polestra, a mathematician at Blockstream, who decided to pick up the torch and progress MimbleWimble towards an implementable blockchain (Blockstream is a global leader in blockchain technology, founded in 2014 by many of the leading Bitcoin Core developers — Adam Back, Gregory Maxwell, Pieter Wuille, Jonathan Wilkins, and others. According to Crunchbase, Blockstream has raised over $100M through three funding rounds to date). In October 2016, Polestra published a more in-depth white paper formalizing how a MimbleWimble blockchain would actually work. Conversion of this white paper into code, leading to what we know as Grin and Beam today, took off from there.

At a high level, MimbleWimble is probably closer to Monero than ZCash; like Monero, it utilizes Confidential Transactions and CoinJoining to encrypt transactions, and its rangeproofs are closer in form to that of Monero’s bulletproofs than ZCash’s Zk-Snarks. However, MimbleWimble is similar to ZCash in that its blockchain protocol was uniquely designed to integrate privacy into the core code (Although MimbleWimble as a whole was a novel proposal for a blockchain, most of the individual concepts that make up the full protocol were already established and proven cryptographic concepts either implemented in Bitcoin Core or included in Bitcoin’s developer library).

Monero, on the other hand, has what the industry calls “bolt-on” privacy; its blockchain is a descendant of a legacy blockchain that was not inherently private, and it bolts on obfuscation methods (Ring Signatures, Stealth Addresses) on top of the legacy, native protocol. MimbleWimble gained traction in the industry because sensibly, most cryptographers see privacy blockchains with a revised core as advantageous to traditional blockchains with bolt-on privacy. This reinforces the argument in the industry that native layers blockchains should be specialized rather than generalized with specificity in higher layers.

We previously published similar articles on privacy coins Monero and Zcash from this author.