--- layout: post title: Logs for the Monero Research Lab Meeting Held on 2019-09-16 summary: Sarang work, and miscellaneous tags: [dev diaries, community, crypto, research] author: el00ruobuob / sarang --- # Logs **\<sarang>** OK, it's time for the meeting! **\<sarang>** Agenda: https://github.com/monero-project/meta/issues/390 **\<sarang>** Logs posted there afterward **\<sarang>** GREETINGS **\<mikerah>** Hello **\<sarang>** I'll wait a couple of minutes in case anyone else shows up **\<kinghat>** o/ **\<kinghat>** \*the regular crowd shuffles in\* **\<el00ruobuob>** Hi **\<sarang>** Our pal suraeNoether said he may not be available for today's meeting **\<sarang>** But I can share some of the things I've been working on for our ROUNDTABLE **\<sarang>** The ever-clever RandomRun posted an idea for a signature scheme earlier: https://github.com/monero-project/research-lab/issues/56 **\<sarang>** Some updates have been made for efficiency, and I worked up proof-of-concept code: https://github.com/SarangNoether/skunkworks/tree/lrs/lrs **\<sarang>** And a timing/space analysis: https://github.com/SarangNoether/skunkworks/blob/sublinear/triptych.md **\<sarang>** (I gave it the name Triptych as a placeholder, so we have a name to use for clarity) **\<sarang>** It actually beats Lelantus in terms of 2-2 transaction size **\<sarang>** But verification is less efficient **\<sarang>** Also note that security hasn't been proven yet, but it uses a modification by Bootle et al. to a 1-of-N proof by Groth **\<sarang>** and that 1-of-N has good proofs **\<sarang>** Aside from that, I've been working with the Lelantus authors on some ideas to fix its self-spend tracing problem **\<sarang>** And that's coming together nicely **\<sarang>** The CLSAG paper will be submitted to Financial Cryptography this week **\<sarang>** And my CCS funding request for next quarter has been opened: https://ccs.getmonero.org/proposals/sarang-2019-q4.html **\<sarang>** On a more whimsical note, a preprint was just posted that does some analysis on a card-based cipher originally designed by Bruce Schneier for a book: https://arxiv.org/abs/1909.06300 **\<sarang>** It's a neat example of a cipher that appears to resist a good deal of modern cryptanalysis, but can be done using paper, pen, and a deck of playing cards! **\<mikerah>** ElsieFour also has such properties except without the playing cards. **\<sarang>** Ah, and I'd be remiss if I didn't mention the trustless recursive SNARK paper, Halo, that was recently posted by the Zcash folks **\<sarang>** mikerah: I wasn't familiar with that! **\<sarang>** Has it undergone much analysis? **\<mikerah>** Here's the preprint: https://eprint.iacr.org/2017/339.pdf **\<sarang>** neat **\<mikerah>** I'm not sure if it has gone through much analysis as it's a relatively new construction. **\<mikerah>** But you can use paper and pen! **\<sarang>** Halo has some clever ideas in it, but it's worth noting (as usual) that preprints don't undergo peer review, and that Halo currently lacks a soundness proof **\<sarang>** It will be fun to see the new research that comes from its ideas **\<sarang>** Any particular questions on the items that I mentioned? **\<mikerah>** How would the ideas from lelantus get implemented in monero? **\<sarang>** Its transaction model could, hypothetically, be implemented directly **\<sarang>** Using a particular kind of migration transaction to transition older outputs **\<sarang>** It would result initially in a smaller anonymity set **\<sarang>** Currently Lelantus has a tracing issue that's a deal-breaker IMO **\<sarang>** but very recent ideas mean that may not be a problem **\<mikerah>** Would there be traceability problems from the current monero blockchain to this hypothetical lelantus+monero blockchain? **\<sarang>** How so? **\<mikerah>** As in, would it be possible to trace transactions between hard forked blockchains **\<sarang>** In such an implementation, old-style transactions would not be allowed **\<sarang>** Old outputs would undergo a signer-ambiguous transaction to generate a new output commitment that is Lelantus-compatible **\<doxxy>** sarang: greets **\<sarang>** So a migration is trivially distinguishable, but retains the same kind of signer ambiguity that exists now **\<sarang>** hi **\<sarang>** To be clear, there are no plans to implement this AFAIK **\<mikerah>** I see. I guess more work would need to be done on this front. **\<sarang>** It's all just research **\<sarang>** Anyway, that's what I've been working on **\<sarang>** Does anyone else wish to share interesting research? **\<sarang>** OK! **\<sarang>** Well, in that case my ACTION ITEMS are administrative stuff for FC submission, ongoing analysis of Lelantus modifications and proofs, and returning to some existing recent proving systems **\<sarang>** Before we adjourn, is there anything else to discuss? **\<gingeropolous>** i don't have any research im working on, but im enjoying banging my head regarding the randomx branch prediction problem **\<sarang>** Go on! **\<gingeropolous>** so, big chunk of CPU silicon dedicated to branch prediction. Turns out a lot of the methods use neural networks kinda thing (called perceptron at one point). **\<gingeropolous>** however, problem is that randomx is random - its random whether a branch will be taken **\<gingeropolous>** and when somethings random, hard for machine-learning / pattern recognition to get any gains **\<sarang>** Makes sense **\<gingeropolous>** however, if you try and seed random into the program (such that a branch predictor could find some emergent pattern), this information could be harvested by an ASIC or some other mitigation **\<gingeropolous>** so, my head sorta got stuck at that point... and if it'd be possible to somehow hide the emergent pattern... and then all the thought threads frayed **\<sarang>** So, using information from existing CPU architectures in order to develop better specialized hardware? **\<sarang>** Or information from any kind of well-designed predictor, I suppose **\<gingeropolous>** well the general randomx problem is to make a PoW that leverages stuff in CPUs. **\<gingeropolous>** and branch prediction is underleveraged due to the problem i just described **\<sarang>** Ah, ok **\<sarang>** I don't know enough about CPU branch prediction to fully appreciate this, but it sounds interesting nonetheless **\<sarang>** Anything else of interest to share before the meeting ends? **\<sarang>** All righty then **\<sarang>** Thanks to everyone for being here; we are now adjourned! **\<sarang>** Logs will be posted shortly