monero-site/_posts/2019-04-15-logs-for-the-Monero-Research-Lab-meeting-held-on-2019-04-15.md

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---
layout: post
title: Logs for the Monero Research Lab Meeting Held on 2019-04-15
summary: Surae work, Sarang work, and miscellaneous
tags: [dev diaries, crypto, research]
author: el00ruobuob / sarang
---
# Logs
**\<sarang>** Let's begin our meeting!
**\<sarang>** 1. GREETINGS
**\<sarang>** Hi
**\<[-mugatu-]>** o/
**\<sarang>** Quiet day today...
**\<sarang>** But I suppose we can still move to 2. ROUNDTABLE
**\<sarang>** suraeNoether: care to go first today?
**\<suraeNoether>** sure, my cat is missing and i want to go look for her, so i'm going to make this quick
**\<sarang>** :(
**\<sarang>** Understood
**\<suraeNoether>** CLSAG signatures are fast and small, they are so fast and small that my naive colored-coin approach could support two assets and still be faster and smaller than our present MLSAG scheme
**\<suraeNoether>** i'm not recommending coloring monero, but commenting on overall speed, it's nuts
**\<suraeNoether>** however, as sarang mentioned, there is a key image problem i'm looking into
**\<suraeNoether>** it's possible rectifying them will cost us some of those gains
**\<sarang>** Yeah, I don't think a straightforward LSAG reduction works here
**\<suraeNoether>** in the meantime, i'm handing CLSAG off to sarang for at least 7 days so i can focus on MRL11
**\<sarang>** But I wonder if a redefinition of the security requirements to accommodate the new linking will be sufficient
**\<suraeNoether>** since we're rounding the corner on that, it's my top priority, and i want to get CLSAG out of sight for a few days
**\<sarang>** righto
**\<suraeNoether>** okay, i'll be back later today, hopefully with suraecat
**\<sarang>** Thanks, and best of luck with your search
**\<sarang>** I completed the building blocks for a simple Lelantus transaction flow (insecure example code in agenda)
**\<sarang>** and am in contact with the paper's author to discuss some privacy aspects of the construction
**\<sarang>** the CLSAG example code has been updated to reflect some changes
**\<sarang>** and, as suraeNoether said, still working on proper formalization, which is trickier than expected
**\<sarang>** The output selection algorithm discussed here still has an open PR from moneromooo that needs eyeballs
**\<sarang>** PR 5389
**\<needmoney90>** Hi
**\<sarang>** yo
**\<needmoney90>** Will lurk mostly.
**\<sarang>** Does anyone else have research to share?
**\<needmoney90>** Just announcing presence
**\<sarang>** Otherwise we can keep waxing poetic about CLSAG definitions
**\<sgp\_>** here now
**\<sarang>** :/
**\<sarang>** Hi suraeNoether
**\<sarang>** sgp\_:
**\<sarang>** bah, silly autocomplete
**\<moneromooo>** I have these multi user txes going in the background, and I am wondering whether the 'a' values can be reuesd for multiple outputs.
**\<sarang>** Remind me what these values are/
**\<needmoney90>** What's the status on M-of-N multisig?
**\<moneromooo>** The idea is to make 16 actual outs for the "same" logical output, so they get shuffled as new outputs are added.
**\<sarang>** (our notation is often inconsistent)
**\<moneromooo>** And I don't know whether it's safe to keep those. I assume sharing them with other usesr of the same tx is not good.
**\<dEBRUYNE>** \<suraeNoether> however, as sarang mentioned, there is a key image problem i'm looking into \<= This is referring to CSLAG right?
**\<sarang>** dEBRUYNE: yes
**\<sarang>** there are no such issues with MLSAG
**\<dEBRUYNE>** All right, thanks for clarifying
**\<sarang>** The problem refers to the fact that trying to reduce CLSAG to LSAG with an aggregated key yields the wrong key image
**\<moneromooo>** a is the random secret keys generated at proive time to create the pseudoOuts.
**\<sarang>** Hmm ok
**\<sarang>** You asked me to review this earlier, and it completely slipped my mind
**\<sarang>** I'll look for the code snippet you sent in PM
**\<sarang>** to ensure I don't get wrong the terms you're referring to
**\<moneromooo>** ty
**\<sarang>** sgp\_: did you have something you wished to discuss too?
**\<sgp\_>** I don't believe so
**\<sarang>** Well, this meeting is turning out to be quite short :D
**\<sarang>** moneromooo: anything specific, aside from the reuse question you posed?
**\<sarang>** (to discuss here, I mean)
**\<moneromooo>** Not at the moment I think.
**\<sarang>** OK, I suppose we can move right along then
**\<sarang>** to 3. QUESTIONS and 4. ACTION ITEMS
**\<sarang>** While suraeNoether continues working on matching/churn via MRL-0011, I have several things for the week
**\<sarang>** Now that CLSAG reduction to LSAG is proving so problematic, I want to see if definition modifications for the LSAG proofs will suffice for our use case
**\<sarang>** I'll be checking on moneromooo's question shortly (apologies for letting that slip by)
**\<sarang>** as well as more work on Lelantus transaction flows
**\<dEBRUYNE>** sarang: Have you consulted RandomRun regarding this problem btw?
**\<sarang>** suraeNoether and I have been in contact with him throughout the development process
**\<sarang>** I don't believe this problem has practical effects on CLSAG's security, only in the complexity of the formalization
**\<sarang>** Any other questions or action items on people's minds?
**\<dEBRUYNE>** I see, so it does not render the scheme infeasible?
**\<sarang>** Heh, depends
**\<sarang>** If we end up not being able to prove secure under proper definitions, that's a bit of a quandry
**\<sarang>** but in the worst case, we decide not to adopt the scheme, and are right back to where we are now
**\<dEBRUYNE>** True, better safe than sorry I guess :p
**\<sarang>** However, the space and time savings are so compelling that it's worth the effort
**\<sarang>** ~25% space savings and 15% time savings for a 2-2 transaction
**\<sarang>** (in the signature portion)
**\<needmoney90>** Not bad
**\<sarang>** OK, any last questions before we formally adjourn?
**\<sarang>** Righto, in that case, we are adjourned. Discussion can of course continue
**\<sarang>** Logs will be posted shortly to the GitHub agenda issue