--- layout: post title: Logs for the MRL Meeting Held on 2020-02-19 tags: [dev diaries, crypto, research] author: asymptotically / Sarang --- # Logs **\<sarang\>** OK, let's get started with the meeting **\<sarang\>** GREETINGS **\<sgp\_\>** hello :) **\<n3ptune\>** Hello **\<needmonero90\>** I caught the meeting! **\<needmonero90\>** I would like to note that the meetings are not listed in the calendar **\<needmonero90\>** idk if thats intentional **\<sarang\>** Which calendar? **\<UkoeHB\_\>** Hi **\<sarang\>** And how are meetings applied to it? **\<ArticMine\>** Hi **\<sarang\>** Meeting times/agendas are always listed as meta repo github issues **\<sarang\>** Anyway, does anyone wish to begin the ROUNDTABLE with research topics of interest? **\<UkoeHB\_\>** Yes **\<sarang\>** Take it away UkoeHB\_ **\<UkoeHB\_\>** I finished designing an escrowed marketplace 'protocol' which hopefully solves issues encountered by rbrunner in his openbazaar integration analysis. Also, multisig and txtangle have been finalized. **\<UkoeHB\_\>** https://www.pdf-archive.com/2020/02/19/zerotomoneromaster-v1-0-28/zerotomoneromaster-v1-0-28.pdf **\<sarang\>** Neat **\<UkoeHB\_\>** Finally, I had an idea for reducing minimum fee variability, and likewise for putting antispam directly in the protocol instead of relying on minimum fee **\<sarang\>** Are you seeking analysis on those? **\<UkoeHB\_\>** Which is issue #70 **\<UkoeHB\_\>** They are open for comments any time anywhere **\<UkoeHB\_\>** Ah and sarang provided a draft for a tx knowledge proof chapter **\<sarang\>** aye **\<UkoeHB\_\>** (not really my research :p) **\<sarang\>** Heh, it's more of a summary of what's in the codebase (and some changes) **\<sarang\>** I look forward to reading the update draft you linked **\<UkoeHB\_\>** A number of topics here are lonely and want attention btw https://github.com/monero-project/research-lab/issues **\<UkoeHB\_\>** \end **\<sarang\>** Thanks UkoeHB\_ **\<sarang\>** Any questions or comments on those topics from anyone? **\<ArticMine\>** Yes **\<sarang\>** Please go ahead! **\<ArticMine\>** I have taken a look at issue 70 **\<ArticMine\>** It actually has serious implications **\<ArticMine\>** When the LT medium increases substantially **\<ArticMine\>** I do have an idea for a solution **\<ArticMine\>** Very preliminary at this stage **\<ArticMine\>** As for an interim fix **\<ArticMine\>** The est is to pay the high or at least normal fee for escrows that are expected to last past the next hard fork **\<ArticMine\>** I will have comments on the issue in the next two weeks **\<ArticMine\>** end **\<sarang\>** Thanks ArticMine **\<sarang\>** Any other questions/comments from the topics presented by UkoeHB\_? **\<sarang\>** Righto **\<sarang\>** I'll share a few things **\<sarang\>** First, the Stanford Blockchain Conference is happening right now (and the next couple of days), and has streaming available: https://cbr.stanford.edu/sbc20/ **\<sarang\>** Second, I did some math/code related to multiparty stuff for next-gen protocols **\<sarang\>** Third, I worked on code and write-ups for transaction proofs, both for an updated PR and for inclusion in Zero to Monero for better documentation **\<sarang\>** Fourth, I used chain data from n3ptune and friends to do better estimates of the cumulative effects of next-gen protocols **\<sarang\>** both in chain growth and verification time **\<sarang\>** Major caveat: these assume the same input/output distribution as the current chain, and are \_estimates\_only\_ **\<sarang\>** and apply to post-bulletproof chain data only **\<sarang\>** https://usercontent.irccloud-cdn.com/file/ijaEAI7m/size.png **\<sarang\>** ^ this link shows the total chain growth estimates for various protocols with varying ring size **\<sarang\>** namely, from 16 to 1024 in powers of 2 (lines for visual aid only) **\<UkoeHB\_\>** Sarang would you mind adding an indicator for MLSAG and CLSAG at the 11 ring size 'point'? For reference **\<sarang\>** Sure, let me grab that data from my spreadsheet **\<sarang\>** hold please **\<UkoeHB\_\>** Or the super steep slope from 11 to 20 lol that goes off that chart **\<sarang\>** Heh, I had that data but didn't include it since it's crazy linear **\<sarang\>** I'm running the N=11 code for MLSAG/CLSAG, which I don't have handy **\<sarang\>** Anyway, I'll pull up the time data while we wait **\<sarang\>** https://usercontent.irccloud-cdn.com/file/T7uWoFEp/time.png **\<sarang\>** ^ verification time estimate for \_group\_operations\_only\_ at varying ring sizes **\<UkoeHB\_\>** I think it's interesting that all these protocols/signature schemes are similar size on the small end **\<sarang\>** All the verification times are linear (up to a logarithmic term due to multiexp) **\<UkoeHB\_\>** Where is tryptich multi hiding? **\<sarang\>** It's underneath Triptych-single **\<sarang\>** They're essentially indistinguishable **\<selsta\>** Does Triptych single have advantages over multi? **\<sarang\>** RCT3-multi suffers due to input padding requirements that still have a linear verification effect **\<sarang\>** selsta: a complete soundness proof :) **\<sarang\>** Update on MLSAG/CLSAG size estimates... **\<UkoeHB\_\>** Could you make a smaller graph from 0 to 128 ring size? Since those large ones seem pretty unreasonable **\<sarang\>** At N=11, MLSAG for that chain range is 7.84 GB, while CLSAG is 5.84 GB **\<sarang\>** (the actual size of that chain range is 7.9 GB) **\<sarang\>** https://usercontent.irccloud-cdn.com/file/DFhClmEe/time-small.png **\<sarang\>** ^ same time data, zoomed in **\<UkoeHB\_\>** Perfect thanks :) are time estimates for CLSAG/MLSAG available? **\<sarang\>** Heh, just writing that out **\<sarang\>** I have very early estimates on that, which are tricky since multiexp doesn't apply, and hashing is nontrivial **\<sarang\>** MLSAG N=11 estimate is 29.9 hours for that chain range (but I have \_not\_ double-checked it) **\<ArticMine\>** What hardware was used for the verification time calculations? **\<sarang\>** It's a single core on a 2.1 GHz Opteron machine, with a bonkers amount of RAM **\<sarang\>** I would rely on the timing data only for comparisons, not absolute values **\<ArticMine\>** age of CPU? **\<sarang\>** I am still in the process of getting CLSAG data, which requires additional test code **\<sarang\>** It's a gen-3 Opteron, if that's what you mean **\<UkoeHB\_\>** Is there a way others could run the same tests? **\<sarang\>** Again, only estimates using performance test code **\<sarang\>** For next-gen protocols, it's quite easy **\<ArticMine\>** Yes great it does give an idea thanks **\<sarang\>** Well, somewhat easy **\<sarang\>** You need to get multiexp performance timing data and use a linear interpolation that you plug into the simulator **\<sarang\>** For MSLAG/CLSAG you need to run more operation performance data **\<sarang\>** This is the simulator, which is still WIP: https://github.com/SarangNoether/skunkworks/blob/sublinear/estimate.py **\<Isthmus\>** https://usercontent.irccloud-cdn.com/file/HuPcfLdT/image.png **\<sarang\>** But again, it's tricky to do comparisons between MLSAG/CLSAG and the next-gens **\<Isthmus\>** (drive by data) **\<sarang\>** Wow, that's quite low **\<Isthmus\>** Oh yeah, the numbers are one thing. But moreso, we should all be more alarmed that analyzing something like this is possible for an outside observer **\<Isthmus\>** ;-) **\<sarang\>** Yep, and has certainly been a topic of interest! **\<Isthmus\>** It's a privacy risk to use subaddresses right now... **\<Isthmus\>** Anyways, I gotta bounce, sorry to spam n run **\<sarang\>** OK thanks for sharing the data Isthmus **\<sarang\>** Another good reminder that I/O structure reveals some information about subaddress use **\<sarang\>** Since Isthmus had to leave, were there other questions/comments on the data that I shared above? **\<sarang\>** UkoeHB\_: if you want to run tests as well, let me know after the meeting and I can let you know how to get the numbers you'll need **\<UkoeHB\_\>** My computer is quite weak, was just asking for viewers :) **\<sgp\_\>** sarang: can you remind us on the plans to fix this subaddress thing? **\<sarang\>** ah ok **\<sarang\>** Requiring separate tx keys per output is a good idea, but IIRC didn't have a huge amount of support when last brought up **\<sarang\>** FWIW the size data that I presented for next-gens assumes a separate tx key per output **\<UkoeHB\_\>** Is that necessary for the protocols? **\<sarang\>** For the proving systems, you mean? No, not at all **\<sarang\>** They don't care how you get signing keys **\<UkoeHB\_\>** Can you estimate the amount of additional pub key data? Num outs \* 32 and num tx \* 32? **\<sgp\_\>** sarang: why did it not get support now? complexity? size? verification time? **\<sarang\>** My numbers for MLSAG/CLSAG include separate tx keys too! **\<sarang\>** Also: n3ptune's dataset includes the pubkey counts **\<sarang\>** So I could run that separately for a more direct count **\<UkoeHB\_\>** With only 3% subaddress adoption, the difference is likely on the order of 100MB **\<UkoeHB\_\>** Or 2% of total size I think **\<sarang\>** that's probably a good order-of-magnitude estimate **\<sarang\>** But IIRC scanning requires checking all pubkeys **\<sarang\>** So either there needs to be a specified correlation, or there's added complexity in scanning **\<UkoeHB\_\>** I think it costs ~1GB for 30mill pub keys btw **\<sarang\>** I think moneromooo had a better idea of the impacts, when it was brought up earlier **\<sarang\>** FWIW I think it's a good idea unless it's very compelling not to due to complexity **\<sarang\>** OK, we're running up to the one-hour mark... **\<sgp\_\>** obviously without this change, the impacts are quite negative for network privacy........ **\<sarang\>** It's differentiated data, but it doesn't leak \_which\_ outputs are subaddress-destined **\<sarang\>** (not that I'm saying that's a good reason to keep the current approach) **\<UkoeHB\_\>** It's quite a lot of unused data, I'm a bit skeptical **\<sgp\_\>** just reveals "one of this outputs goes to a subaddres?" **\<sarang\>** UkoeHB\_:? **\<UkoeHB\_\>** A lot of dummy data **\<sarang\>** sgp\_: it reveals the number of subaddress outputs **\<UkoeHB\_\>** sarang all it reveals is at least one of the outputs must be to a subaddress **\<sarang\>** Doesn't it reveal the total number of sub outs? **\<UkoeHB\_\>** No **\<sarang\>** orly **\<UkoeHB\_\>** How would it? **\<UkoeHB\_\>** Number of additional pub keys always equals number of outs **\<UkoeHB\_\>** Even if nonsubaddress **\<UkoeHB\_\>** How is the CLSAG paper going? **\<sarang\>** Hmm, for some reason I thought otherwise; noted **\<sarang\>** I'm still waiting for suraeNoether **\<sarang\>** He wanted to continue working on his ideas for the security model **\<sarang\>** So unfortunately I am not the one to ask **\<sarang\>** OK, is there anything else of interest to share? **\<sarang\>** (Would be a good idea to continue discussing this after meeting, or on an issue, to keep it alive) **\<sgp\_\>** definitely need an issue for it **\<sarang\>** All righty then; thanks to everyone for attending today **\<sarang\>** We are adjourned!