Earlier this year, David Burkett, the developer of Grin++, was scheduled to speak about his work on Mimblewimble extension blocks for Litecoin. Like many events this year, it had to be rethought. His talk was to be hosted by Blockchain in the Burgh, a community of crypto enthusiasts, educators, and early adopters. They have monthly meetups in the Pittsburgh area to bring further clarity to blockchain and crypto, as well as spur further adoption of the tech. Since the COVID pandemic, their meetups have been hosted online with the help of Bits and Tokens, a blockchain media company. Broadcasting from this virtual venue, interest was not stifled. A total of 56 attendees were registered for the event August 29 including, Litecoin creator, Charlie Lee.

David started off his casual conversation with us all by explaining the spelling of Mimblewimble, as many have had troubles with this. Mimblewimble is spelled with a capital “M”, a lower-case “W”, and it is all one word. You are now all learned in this art! With that formality out of the way, David got into the juicy stuff. He began explaining the privacy within the Mimblewimble protocol and how it functions alongside Litecoin.

With typical transactions across a network, everything is transparent. The amounts of tokens exchanged and addresses involved are in view for anyone to check upon. With the help of the Mimblewimble protocol, some privacy should be lent to our money and how we choose to use it. No amounts, no addresses, no possibility of linking a transaction to an address, and nothing is learned through the transaction happening except that it is happening. Running on the Litecoin network, Mimblewimble is built as an extension block. It can be thought of as a sidechain, but an extension block is a second layer mined alongside the original block. This soft fork gives the network further functionality.

David went on to explain that the mechanism for enabling some privacy is actually a big piece of code and scales terribly within a network, but Mimblewimble implements a few tricks that actually increase scalability. As transactions are mined within a block, they are joined together in what is called a coinjoin. Several transactions are all placed together so that the boundaries of the individual transactions are no longer visible. You can see there are inputs and outputs involved in the transaction, but can’t discern any links between any of them. A trick that improves scalability on-chain lies within what happens after the transaction is made. The data of the coin being spent is not held onto, but the data of the unspent coins is. This property or feature is called cut-through. Because of this, Mimblewimble networks offer privacy, are cheaper to run and scale far easier. The initial download of the blockchain is also sped up by cut-through. Less data kept within transactions means less data on-chain.

Going on further, David showed how a MW transaction doesn’t function as a normal one would. The sender and receiver work together to create the signature that conceals the transaction. These signatures are a type called Schnorr Multisignatures. Through what is a complicated process, the transaction is again made simpler and in a way streamlined. The network participants work to piece a signature together. This saves space within the transaction on the blockchain and conceals the addresses of the participants. The combined use of a coinjoin and Schnorr multisignatures speeds up transactions verifications, keeps the blockchain lighter, and gives the user added levels of privacy.

David wasn’t shy about areas of MW that can be improved upon. MW is still an early in its development, and David expects it will look far different as time goes on and they continue to innovate the Mimblewimble protocol. He stated that Mimblewimble is not something to be compared to Monero or Zcash. What MW gives is transactions with increased privacy while still having scalabilty. However, He is working towards ways of improving the privacy of the protocol even further. Payjoins, where both transaction participants send coins so the original sender is not known. Dandelion broadcasts which hops a transaction around a network before broadcasting the transaction. In this way the original sender is not broadcasting the transaction and is kept concealed. Payment hubs are another idea to further distance senders and recievers.

The Mimblewimble dev is most excited and nervous about the upcoming testnet that will show MW as an extension block on the Litecoin Network. He said that there are many pieces that have not yet been tested together. So there will be plenty to learn and much work to be done. Most of the work thus far has been on the node side of transactions and verification. The wallet side and creation of transactions is up next, and David expects that by the end of 2021, if miners and community agree, the Litecoin network will be running with Mimblewimble extension blocks with no changes to the miners or the pools.

You can keep up with all David is doing @DavidBurkett38 on Twitter. You can also stay up to date with all the meetups Blockchain in the Burgh and Bits and Tokens are putting together. You can follow them respectively on Twitter, @BlockchainBurgh and @BITSANDTOKENS. Big shout out to Laura Taylor and Rebecca White for organizing this!

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