September 16, 2019

**<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

Post tags : Dev Diaries, Cryptography, Monero Research Lab