Litecoin MimbleWimble June Summary Update

This update was written and provided by Litecoin MimbleWimble lead developer. David Burkett.

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documentation

I spent time documenting all code changes to help auditors. For those who are interested, here is a list of recent technical documents (some of which are only partially complete) that describe MWEB changes:

LIP-0002 – It describes the process of adding extension blocks to LTC, including explaining how peg-in, peg-out, and transaction integration work.

LIP-0003 3 – This is the original design of the Mimblewimble expansion block. It’s a bit outdated, but should give you a high-level understanding of how it works.

LIP-0004 – This describes our approach, which supports one-way tx instead of relying on interactive transactions like traditional Mimblewimble.

LIP-0005 – Although we’re still filling in missing data structures, this document documents the P2P protocol changes and explains how MWEB transactions and blocks are serialized.

Consensus Rule 1 – Although it is not a comprehensive list, it describes the most important consensus rules.

kernel – It explains how the kernel is serialized, the various features supported (such as lock height), and how new features can be soft forked in the future.

data storage – Describes the new database tables and data files added.

stealth address – How to generate stealth addresses, how to support subaddresses, how to serialize addresses, etc.

Cleaned up sync 1 – Describes how clean synchronization will be supported in future releases.

Coding and Testing

We’ve independently reviewed all node logic to find ways to improve security and performance, resulting in significant code and design improvements.

Kernel MMR is now block-by-block instead of a continuously increasing MMR. It was determined that there was not much benefit to using cumulative kernel MMR, so switching to per-block MMR would reduce the time spent hashing and require much less disk space to store the MMR.

Switched from sha256 to blake3, which is much faster, for all MWEB hashes.

A new stealth address format that is more consistent with previous address types along with better error detection.

A more compact serialization format for all MWEB data structures results in less disk space usage and slightly higher throughput with less data transferred between peers.

better test coverage

Audit and Review

Now that we’ve officially delivered the final code changes and documentation to Quarkslab, we’ll have a more detailed timeline for this at any time.

I created a new Code Review 5 containing the most important changes to the Litecoin consensus code. It’s much smaller and more focused than the libmw reviews from a few months ago, so hopefully we’ll have more reviewers and get faster feedback from other developers.

Wenmweb.com We’ve made some changes to our projected schedule for 23, but overall we’re still working toward activating MWEB by the end of the year.