July 29, 2019

**<sarang>** OK, let's begin

**<sarang>** Hello all

**<sarang>** Logs of this meeting will be posted to the GitHub agenda issue afterward

**<sarang>** GREETINGS

**<suraeNoether>** greetings!

**<kenshamir[m]>** hey

**<sarang>** Whoops, here is the current agenda: https://github.com/monero-project/meta/issues/377

**<sarang>** Let's go ahead with ROUNDTABLE

**<sarang>** I've been working hard on an RCT3 implementation, integrating some nice optimizations and seeing if it's possible to get key images working as expected

**<sarang>** This also led to a bunch of other library updates that the code relies on

**<sarang>** So generally just a lot of coding

**<sarang>** I also gave a fun lecture on the Enigma cipher machine and the math behind it, which is always fun ;)

**<suraeNoether>** nice, what was that for? a meetup or something?

**<sarang>** A friend teaches at a university and thought it would be good for an undergrad crypto class

**<sarang>** Since the Enigma break is all about permutation groups

**<suraeNoether>** nice

**<sarang>** I should be able to finish up an integration of the BP inner product verifier optimization into RCT3 shortly

**<sarang>** Then, of course, DEF CON approaches!

**<suraeNoether>** neat

**<suraeNoether>** i have a very dirty branch on my computer with my matching simulations and experiments being worked upon

**<sarang>** How are those going?

**<hyc>** defcon - anyone got grasshopper repellent?

**<sarang>** -____-

**<suraeNoether>** i've proven all the theorems necessary to prove that the algorithm in graphtheory.py does what i claim it does, and i'm currently testing that my simulated ledgers are doing what i expect.

**<sarang>** noice

**<sarang>** Will be very neat to see the results, and to see if/how they can work with the analysis that Isthmus et al. are doing on Monero and Zcash

**<suraeNoether>** in addition to that, i have a bunch of MAGIC stuff I need to get done, and my discussions with isthmus' digital forensics work are leaning in that direction

**<suraeNoether>** i'm thinking the content of this project may take up more than two papers :\

**<sarang>** Cool!

**<sarang>** Also worth noting that the CLSAG paper has been updated on IACR, thanks mainly to kenshamir[m]'s comments and questions

**<sarang>** kenshamir[m] has also been working on a Rust implementation of CLSAG/MLSAG using the dalek library

**<suraeNoether>** hyc: i hear grasshoppers are delicious, i wonder if any of those fancy vegas michelin star restaurants are capitalizing on the swarm

**<sarang>** Anything you'd like to share on that, kenshamir[m] ?

**<kenshamir[m]>** Hi, the library is finished, not interopable with monero because it uses a different curve though. The numbers are quite impressive and I believe it is due to the way cLSAG was created

**<sarang>** aw shucks

**<sarang>** Will be great to see your MLSAG vs CLSAG numbers at different ring sizes

**<suraeNoether>** i believe there was a question re: ristretto and multi-exp like pippenger right before the meeting that would be relevant here?

**<sarang>** I brought it up a while back because we handle different linear combination sizes _very_ differently in the codebase

**<scoobybejesus>** is that rust code in a public repo?

**<sarang>** We use no fewer than 4 methods

**<kenshamir[m]>** The numbers above were for different ring sizes, I may have mis-typed key sizes by accident

**<kenshamir[m]>** 256 and 512 were for the decoy sizes; if I was not clear

**<sarang>** A big part of the reason CLSAG verification is faster than MLSAG is because of the introduction of a new linear combination evaluation algorithm

**<sarang>** kenshamir[m]: can you link them again for the logs?

**<sarang>** (if comfortable having them public)

**<kenshamir[m]>** <scoobybejesus "is that rust code in a public re"> Not the cLSAG code, once I add documentation and sanitise it I can post it in here

**<sarang>** ty

**<kenshamir[m]>** <sarang "kenshamir: can you link them aga"> Yep sure

**<scoobybejesus>** :)

**<sarang>** What does "without Pippenger/Straus" mean? Simple iterative evaluation of linear combinations?

**<kenshamir[m]>** Yep exactly

**<sarang>** Impressive numbers

**<sarang>** Of course, it's a different hash function

**<kenshamir[m]>** I just did scalarbase mult in a for loop

**<kenshamir[m]>** haha yeah that too

**<suraeNoether>** hmmmmm

**<sarang>** But if the hash function is the same across both of your CLSAG/MLSAG, then the relative numbers are good

**<suraeNoether>** something that is both faster and smaller and with equivalent security is a no-brainer for implementation (pending audits)

**<sarang>** Speaking of this, still in contact with potential auditors, who are moving very slowly

**<sarang>** Nothing to report on that front :/

**<suraeNoether>** the improved space allows for a logarithmic increase in verification time without actually slowing down the network (at least when it comes to new nodes downloading the network). judging by these numbers, a ring size of 16 or 32 is no longer like pouring molasses or concrete onto the network

**<sarang>** OK, any other interesting research to report?

**<gingeropolous>** re: audits, or roll-out in general. Is this the kind of thing that could be rolled-out in parallel with existing? i.e., have an overlap, where the network uses the existing as the primary / default, but can optionally use the new thing, and then once new thuing is vetted, just prune the old?

**<hyc>** ^ slow auditors - a lot of people are on summer holiday now

**<gingeropolous>** or, switch to the new and no longer have to relay / verify the old style during the overlap?

**<suraeNoether>** sarang: am i wrong in saying that gingeropolous is correct that clsag could be implemented in parallel before mlsag is deprecated?

**<hyc>** we had a 24hr overlap in the last hardfork for this sort of thing

**<gingeropolous>** this would be kinda different.

**<sarang>** I suppose it could be overlapping, provided the fee model supports it properly

**<sarang>** I don't really see why this would be useful

**<gingeropolous>** i dunno. i'm just opening the conversation regarding the model that all new things need to be audited

**<gingeropolous>** i mean, obvi auditing is great

**<sarang>** yes

**<gingeropolous>** but its not perfect

**<dEBRUYNE>** hyc: Yeah in general, summer constitutes low activity

**<sarang>** It's good for inspiring confidence, as well as the obvious benefits of catching any errors

**<kenshamir[m]>** Can Monero benefit from using bulletproofs for arithmetic circuits?

**<dEBRUYNE>** gingeropolous: Didn't we discuss that kind of model for Bulletproofs or RingCT too?

**<sarang>** Likely not, with our current tx model

**<gingeropolous>** yeah dEBRUYNE

**<sarang>** The scaling isn't great

**<dEBRUYNE>** I think it was shot down for good reasons, but I cannot remember them exactly :-P

**<gingeropolous>** i think that was post audit though

**<sarang>** and we have hash functions, which screw things up

**<sarang>** Zooko had a slide in some presentation where his team estimated the verification time for a circuit with the complexity of Sapling (Sprout? don't recall)

**<sarang>** and BP verification was O(1 s)

**<sarang>** Compared to our current verification time which is probably 1/50th of that

**<sarang>** maybe 1/100th

**<kenshamir[m]>** yikes

**<suraeNoether>** kenshamir: if we designed an arithmetic circuit to describe a ring confidential transaction language, then yes, but that's sort of what RCT3 and omniring and lelantus try to do… sarang, i think zooko was showing "what it would look like for a Sapling transaction language to be proven in the bulletproof setting" not ring confidential transactions, so it's not clear to me whether it'd be slower.

**<suraeNoether>** in our setting

**<suraeNoether>** with the exception of our non-AC-compatible hash function

**<dEBRUYNE>** sarang: That's verification time for fully shielded transactions?

**<suraeNoether>** dEBRUYNE yeah, iirc

**<dEBRUYNE>** Yikes

**<sarang>** Yeah, that timing was just to give an example of what a production-size tx circuit might look like

**<dEBRUYNE>** Especially given that, as far as I know, you have to run a full node in order to properly perform fully shielded transactions

**<dEBRUYNE>** Anyway, I digress :-P

**<sarang>** Anyway, suraeNoether is right in that RCT3 and Omniring try to bring the BP benefits to specific languages used to prove RingCT-type statements

**<sarang>** which is why we're interested in them

**<suraeNoether>** yeah, bulletproofs for use in SNARK-style languages is like… uhm… putting a large-diameter turbofan engine into a Mini Cooper. It's not going to do what you think it's going to do.

**<sarang>** BPs can be much more efficient for languages built for it

**<sarang>** which is why range proofs are so efficient

**<kenshamir[m]>** haha

**<suraeNoether>** indeed

**<suraeNoether>** moving along

**<sarang>** heh

**<sarang>** ok, other research?

**<sarang>** Or QUESTIONS, from the agenda?

**<sarang>** OK then! To ACTION ITEMS

**<sarang>** I'll be finalizing some things for my DEF CON talk, workshop, and panel; and finalizing some RCT3 integration optimizations

**<sarang>** suraeNoether: ?

**<suraeNoether>** oh gosh sorry

**<suraeNoether>** i was computing a number sorry about that. :P

**<sarang>** it's 7

**<suraeNoether>** my action items are: work on sims and the experimenter, and work with isthmus to formalize statistical hypotheses for testing all this

**<sarang>** Having data from Isthmus's group will be extremely valuable for this kind of analysis

**<suraeNoether>** actually the number is O(153.58*N), which is the number of bits used to describe the number of possible spend histories at ring size 32 with N outputs.

**<suraeNoether>** which is nutters

**<sarang>** This is all assuming no external information?

**<sarang>** Or other graph-based information on chain reactions and provably-spent outputs?

**<suraeNoether>** merely the total number of self-consistent spend histories

**<sarang>** Ah ok, so for a hypothetical graph

**<suraeNoether>** yeah

**<sarang>** got it

**<gingeropolous>** O(153.58*N) … great. now your math is talking in math

**<suraeNoether>** well it means that for, say, 1000 transactions at ring size 32, there are 2^(153,580) possible spend histories.

**<suraeNoether>** anyway

**<suraeNoether>** (N has to be a lot bigger than the ring size for the above formula to hold btw)

**<sarang>** which is… quite reasonable

**<sarang>** Any other final thoughts or questions before we adjourn?

**<sarang>** OK then! Thanks to everyone for participating. We are adjourned

Post tags : Dev Diaries, Cryptography, Monero Research Lab