Mimblewimble Progress Update Thread

Hey David! Awesome to get updates on this thread. Great to hear the progress :wink:

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As promised, here’s a brief write-up of the design. Mimblewimble Design (libmw)

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Hi David. Thanks for the update.

December Progress:

After months of planning, development of the mimblewimble extension block has officially started! My efforts this month focused mostly around restructuring the core logic that will be shared between Grin++ and LTC. This involves all of the logging, serialization, crypto, error handling, and common data structures (headers/blocks/txs).

Most of this was already written for Grin++, but since some parts were hurriedly coded on a tight time schedule, I’m using this opportunity to go over every line with a fine-tooth comb. As part of this, I’m standardizing patterns that were originally followed inconsistently, backfilling missing tests, and adding better documentation.

The LTC priorities for January will be:

  1. Determine build method - Since the code will now be spread across a few repos, a slightly more complex build process is necessary. I’m still figuring out the best way to handle this, but am currently leaning toward a simplified version of libbitcoin’s build system (https://github.com/libbitcoin/libbitcoin-build)
  2. Define all LTC models - Determine the exact fields and serialization format of the headers & kernels (including signatures)
  3. Move the database implementations over to libmw-core, cleanup to match new standards, and add full tests.

I also will be working on a faster sync mechanism for Grin next month, which LTC will directly benefit from.

For those technical-minded readers who want to follow along as changes are made, feel free to “watch” the following repos:


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Thanks for the updates, David! :grin:

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I have been spiking on MW so we have a plan moving forward but I have just begun. It will be great to launch Litewallet at the same time as Litecoin Core. But it more likely that we will need to do some testing after the updates are live. One of the tech debt issues is tLTC support for iOS.

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Hi Kerry that’s great. We would love to see confidential transactions added into litewallet supporting MimbleWimble

In regards to the last statement about tLTC die iOS what is this?

this is testnet LTC. The code was forked from Breadwallet which was one of the first BTC mobile wallets. They had testnet BTC and the idea was the LTC should have testnet LTC as well. It requires some refactoring in the codebase.

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January Progress:

The biggest news from January is that I’ve found a way to support non-interactive transactions in Mimblewimble! The biggest difficulty with using MW is the need for sender and receiver to communicate, which requires receiver to be online when sending. My proposal, along with an updated version of the write-up that will be released soon, eliminates that need. This removes a major UX hurdle, limits long-term maintenance requirements, and supports receiving via cold-storage, making hardware wallets easier to support.

On the development side, the build process has been determined for libmw, and local builds are working for libmw-ltc (checkout libmw-core and libmw-ltc to the same parent directory, and you should be able to build libmw-ltc). I’ll setup CI/CD in the next month or so, but the important part is multi-repo local builds are working.

I’ve also built out a robust Database framework with transactional capabilities to support atomic updates across multiple tables, and have implemented the block database querying and updates, which is coin-agnostic, and has been partially tested using LTC-specific header and block models.

The security audit results are back from Grin++, so I’ve applied all fixes to Grin++ and libmw, and will be awaiting final review from the auditors. The audit turned out to be a humbling lesson in just how complicated C++ really is. I’ve learned enormously as part of the process, and the Grin++ & libmw codebases are significantly better as a result. A huge thanks again to the contributors in the Grin, Beam, and LTC communities who made that audit possible.

On the Grin++ side, we’ve had a successful planned hardfork, our pre-hardfork syncing issues have been resolved, and Grin++ 0.7.5 is available now which has turned out to be the most stable release yet. For the first time since Grin++'s creation, the support channels are finally quiet, which means more time to focus on actual development. As long as things remain quiet, and I don’t have to focus on putting out fires, I expect an even faster development pace over the coming months.

The priority for February will be to implement the consensus rules for the LTC EB, including all validation and a full suite of tests. This is the most important part of the code, so it will be time consuming to make sure all of the details are correct, and the code has full test coverage. Once that’s complete, I will work on the API for the extension block, so we can start integrating libmw into the existing LTC codebase.

I will also focus on getting the new one-sided tx proposals thoroughly reviewed, and if no major security concerns are found, I will create an LIP for community feedback.

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Thanks for the update. We are looking forward to reviewing the litecoin improvement proposal in March.

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Thanks for the update :+1:

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Thanks for the update, David! You rock. :grinning:

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great going

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Thanks for the update! Glad to hear about the progress!

We need this. We also need more than just this and the usual bitcoin core updates as well.

Any new ideas that are separate from bitcoin core updates like Mimblewimble that make

Litecoin further unique from BTC? Right now the ‘scam coins’ forked coins of Bitcoin, BCH and BSV

are more silver to gold than LTC unfortunately only further enhancements above and beyond BTC

will loft LTC back into at least the same price range as the above scam coins. It still boggles the mind

that LTC is as low in price as it is compared to BCH and BSV. :frowning:

Thanks updata. I will wail new

Don’t worry, it’s going back up thought relative to BTC; a month ago it was at roughly .0057, now up at .0074 :slight_smile: Should continue as the (hopeful) bull market continues to run up.

Happy Leap Day!

February Progress:

The non-interactive transaction proposal has gone through a few design iterations this month. I believe we’ve finally got a design that resolves the issues found with the first write-up, and I’ve turned that into a LIP (https://github.com/litecoin-project/lips/pull/13). I suspect it will still take some time before the LIP has had sufficient review to be considered safe enough to accept, but I’ll continue to keep one-sided transactions in mind as I develop.

Aside from the LIP, I’ve made good progress on the validation rules, but there’s still a lot more to do. I’ve made some modifications to the original kernel design to support the ability to soft-fork in new features in the future. I’ve also started to build out the merkle mountain ranges (MMRs), which are a data structure we use to commit to kernels & outputs. Once the MMR logic is finished, I should be able to get back to the block validation logic. I didn’t get to work on the Node API like I had hoped, but that’s something I also expect to get to next month.

I’ve so far been very hesitant to give exact dates on when things should be finished, because writing blockchain software is difficult, time-consuming, and unpredictable at times. I didn’t want artificial deadlines to force us to rush through parts of the code and introduce defects or security vulnerabilities. Having said that, I think it’s finally time to commit to the first major event…

End of Summer: MW Testnet Launch - This will include all block & tx validation rules, basic p2p messaging, transaction pool, syncing, and the ability to mine blocks. This will NOT include a usable GUI wallet for casual users to test it out. Transactions will likely need to be created manually at first, or via a cli or automated tool.

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Thanks for the hard work & update David.

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