Episode 308 - Avail's Approach to DA with Prabal Banerjee

Transcript

[Music] welcome to zero knowledge I'm your host Anna Rose in this podcast we will be exploring the latest in zero knowledge research and the decentralized web as well as new paradigms that promise to change the way we interact and transact online this week I chat with prel benergy one of the co-founders of the Avail project we cover his background from Academia to joining polygon in 2020 then to the evolution of the Avail project from a proof of concept to an internal brand to eventually spinning

out as a standalone company we then do a deep dive back into the topic of data availability or da we talk about how Avail is built the technological choices they made their use of kzg validity proofs and how they position themselves within the ethereum and wider blockchain ecosystems we talk about the interaction of Da with different parts of the modular blockchain stack and how a veil compares to competing systems like Celestia or Anan da I also get a chance to ask all sorts of like questions about edge cases and what this would mean in a DA based stack and we get to find out how the team at Avail is thinking about this now before we kick off I just want to share a reminder that ZK hack 4 online is happening right now running

from January 16th to February 6th this multi-week event features workshops and puzzle hacking and a job fair there's still a few sessions left so be sure to join us it's all virtual and free I'll add links in the show notes Also earlier this month we opened up the ZK Summit 11 application form for potential speakers and attendees this time around the Zer knowledge Summit will be happening on April 10th in Athens but space is limited and we seem on track to beat all application records with this addition already only folks who filled out the application form will be eligible to to get access to tickets to attend so at the very least if you want to join do get that application in early I've added

the link to that in the show notes as well now Tanya will share a little bit about this week's sponsor Alo is a new layer one blockchain that achieves the programmability of ethereum the privacy of zcash and the scalability of a rollup driven by a mission for a truly secure internet Alo has interwoven zero knowledge proofs into every facet of their stack resulting in a vertically inter ated layer one blockchain that's unparalleled in its approach Alo is ZK by Design dive into their programming language Leo and see what permissionless development looks like offering boundless opportunities for developers and innovators to build ZK apps as Alo is gearing up for their main net launch in q1 this is an invitation to be part

of a transformational ZK Journey dive deeper and discover more about Alo al.org and now here's our episode today I'm here with prabelle bannery one of the co-founders of ail welcome to the show thanks anah thanks for having me and our audience can't see this but you're currently wearing a ZK hack shirt which is awesome thanks for wearing that yeah I guess you guys would like that today we're going to be diving back into the topic of data availability da I've had Celestia on the show before to talk about da I feel I I sort of understand what it is but I know we're

going to dive much deeper into it and kind of cover it again I do want to say one quick disclosure is that ZK validator is actually a validator on Celestia which is kind of competitor to Avail so I just feel like I should throw that out there I'm more familiar with their projects so I'm going to probably bring that up a fair bit um but I'm very excited to learn about a veil in general I've been wanting to do a little bit more of a deep dive into da layers and sort of these tools that live around rollups and and ecosystems so yeah this is very cool to get a chance to talk to you so first off why don't we hear a little bit about where you're coming from what got you started what got you excited yeah how did you start working

on this topic yeah so I think I have been interested in cryptography from around 2013 I was in college uh it always got the my imagination and that's why uh always fiddled with cryptography and cryptographic algorithms and such um after that I wanted to pursue a more academic approach and I joined a PhD program in 2016 uh on cryptology and security that's when I first came into the blockchain world it completely fascinated me the culmination of so many different topics that I had studied till then all kind of came together and all made sense in one application which can fundamentally change um how we how we

use use technology in general and again that was kind of the rabbit hole that I gotten four years into the research I realized that uh of course I'm taking a more theoretical approach studying about algorithms writing some of the new ones and so on like I worked on proofs of retrievability on marketplaces on fairness of data exchange and so on and so forth but I wanted to you know do something more applied I wanted to contribute directly to a use case with which many people can use and that's when I started looking into different solutions polygon which was Matic at that time was one of the major scaling

Solutions who were thinking of scaling ethereum at that point in time uh they were one of the only few ones in production at that point and hence in 2020 I dropped from a PhD program and joined polygon then dropped out yeah ah and question about the timing here so were they still plasma based at the time was that more like a yeah because I know I know a little bit of the eras of the polygon Matic project yeah I think when I joined they had both so there were plasma contracts and then there was POS contracts and we were increasingly seeing uh whenever I joined also like what we were struggling with Plasma in

the sense that what are the pitfalls of plasma how you know General logic had to be written specific contracts for plasma exits and such how that kind of didn't make much sense in terms of the plasma exits and the long cues that you had to maintain and how that was not really a practical solution at that point in time with plasma and increasingly people were preferring to use POS for Simplicity because of how it actually solve the scaling challenges at that point in time and you could really see the push for or you know deprecating plasma as a whole and just pushing and making just a p solution but wasn't the original polygon

POS just like a separate chain a fork of ethereum and then a multisig connecting it I think uh the polygon or the original Matic POS chain was a a different things all together right so they had a uh how I like to think about it is that they have the same kind of architecture what ethereum has today I would say and again I'm stretching it a bit uh so they had the execution engine which was a fork of get which was called bore and then they had a consensus engine which was based on tender or a variant thereof which was Cosmos SDK

based yeah uh the validators used to live or still lives on the hindal Chain which is on tender Min and the execution happens on on board and this gives them the hybrid Ledger kind of a situation where execution can go on with probabilistic finality and then the you know the validators can finalize it later yeah this makes sense I'm just going to correct because it wouldn't have been a for like eth at the time was proof of work but the POS chain was already proof of stake this makes complete sense okay so it wasn't like an exact replica but the connection point was not a ZK rollup it was not cryptographic um just one extra question

here was plas is plasma this is such a kind of basic question but is plasma an economic game is it closer to a fraud proof it's actually not economic game but it's actually also that you can permission permissionless exit now what does it mean is that if at any point in time you think as a user of a plasma chain MH that you are facing a data withholding attack or some form of you know censorship and you want to exit you would be free to you know report that onchain with the last known State and you will be able to exit Okay within a

challenge period which is when other people might have to also Force exit because there can be other attacks where you want to spend a balance which you have already spent on the plasma chain so you come up with a stale balance report it on chain and want to exit and then others will have to come up and submit that no no wait he had actually sent those funds to me and that's why he's not the rightful owner I am and that's why I need to exit and so on so there are this plasma exits became a problem and also Beyond payments it was hard to encode all the business Logic for you know account based uh systems inside those plasma contracts because it

g out pretty complicated once you grew out of something like let's say simple utxl okay okay but anyway go let's go back to that part of the story so we're at the POS state where it is proof of stake I mean I know a lot about the polygon story after that where there's been an investment in ZK and like you know putting together this amazing team of researchers they've since I mean there's there's new chains kind of on the market or coming out that are much more cryptographic when you're joining them so they have these two parallel systems when you join them in 2020 were they already thinking about data availability as a second as a separate thing or would

you say that concept kind of emerged over time they were already thinking about it like when I joined these were this was one of one of the first assignments that I worked on oh no and because the problem was that when you design a plasma game you quickly realize that that you know optimistic execution is great and offchain da is also great but they need to come together to be able to give uh a very you know nice construction which is solid which inherits the security of the base layer but suddenly they are very hungry for data on the base layer and it quickly realized that in this rollup Centric

world how is it or what it is going to look like so even before I joined uh I think they were already discussing that because when I joined their you know pathway was very clear that it is going to be a rollup Centric ecosystem doesn't matter how the rollups get built because there was I think uh a few design like some research papers out there about how rollups can be built a few debates All Out There Will ZK be efficient enough will there be economic guarantees be uh good enough to secure optimistic Solutions and things like that whether there will be an efficient challenge

game that you can play during the fraud proof period once a fraud proof have been submitted will there be efficient fraud proofs to be handled on chain and so on so there were many many questions that were there as far as I can recall but uh the vision was clear that it is going to be a rollup Centric road map uh is how blockchains are going to scale mhm how long were you there actually I was there for almost three years I think a little less than three years so during my time in polygon um I contributed to ail as I said which was one of my first projects there that I started working on also contributed to the POS chain uh a little

bit on the you know the ZK efforts there when the ZK teams came in tried to help them somewhat uh leted their research at some point in time and then you know spun a wh out of polygon last year in March cool before we move on to sort of that spin-out moment I am kind of curious what it was like you had been in Academia looking I'm assuming like if you were researching a lot of the space you were kind of looking into the space but you weren't part of it yet then you made the move over also during some of the craziest time in the industry and I'm sure at polygon just given the 2020 2020 to 2023 that's a wild ride I'm sure yeah like can you talk a little bit

about like just the the going on the other side like if you were excited about that if it gave you energy if you had to readjust maybe because it's so different from Academia I think even during my academic studies I was quite clear that I wanted to be in the industry as I said like my excitement was more about how I can build systems or at least contribute to Building Systems which users can try out rather than have a paper which is awesome to read really great to discuss about but practically is suboptimal or doesn't work or is cannot be implemented and such and that's why even during my four years of research I did around you know three

internships two of which were at IBM research uh and in IBM research I think IBM at that point was working on hyperia fabric I tried to work on hyp of fabric and at that point I mean retrospectively looking at it right now they are already thinking of sequencers and executors and so on because hyperledger fabric had a had a CFT Kafka based sequencing engine and you know we used to criticize that how can an L1 uh be not bft in its ordering layer and how can it be permissioned so there were many criticisms of the hyperledger fabric platform that IBM was working on but at

the same time I learned a lot like it it kind of fundamentally made me think about how you can take uh L1 blockchain and kind of try to bifurcate it into many different layers not all of which have to have the same trust model have the same fall tolerance models and so on and so forth so that that is one part of the story but even after joining polygon I think I learned a huge huge lot it was of course a bit unsettling all through but that's what probably kept me on my toes in some sense because you could like if if you are interested on making impact and you are inside polygon

everything that you do there are thousands of people using it and there can not be anything better than that if if that is what keeps you aake at night right and everything starting from how uh and again I would just go back to that reference right so simple things like how can you have a hybrid Ledger how can you give a finality on a world where only probabalistic finality is given and you know how can you give um something like with provable finality but at the same time have have liveness ensured by decoupling things and so on I think ethereum at that point and paulot as well had pretty solid thoughts and constructions around it so I learned a

lot from them I think many people wrote very very good papers on on these kind of ledgers attacks on etherum and such and it was very interesting to take them and put those research ideas into into action in something like polygon where people are using it where that is a real real pain point something like a reorg was a major major paino in someone using polygon but that was you had to EXP explain to a to a user that it's not either or you have to take in both you have to take in both the probabilistic finality and the liveness together because that's a fundamental dilemma

that you have wow again things like EIP 1559 how can you take those uh transaction pricing mechanism and can actually do it in a much much smaller block time and things like that and then will be you know huge uproar about how transaction prices are going so high and things like that so it was always always extremely extremely interesting I like that idea that you sort of you got a chance to build something that thousands of people would use and it would be stress tested I guess like right away right you you deploy something I I'm I'm sure it wasn't so willy-nilly you weren't just like throwing things out

there see what happens to the blockchain but yeah it wasn't the experience that I think a lot of other builders in the space have had which is they spend a lot of time Building Systems that don't get that many users or maybe don't get users for years in in your case you enter into this company that's already rolling because 2020 was the beginning right like that by that point it was already picking up steam yeah absolutely I think when I joined as I mentioned that it was only one of the few real scaling Solutions which were there in production and team immediately struck me because there was always debate about whether that's the right way to scale but this is the team that always believed that

you know we will find out the right way let's just build a scaling solution make sure that people are able to use it people are able to use ethereum the ecosystem the tooling the same things and still be able to you know benefit from this entire production great chain and uh and it was very very good to see like uh and I keep saying that to others as well there are other problems Which polygon POS chain is kind of encountering be because it has all those traction because it has all those activity things like latencies things like State IO read writes things like State bloat which are at the

Forefront of kind of what are the kind of things that you need to make an evm compatible chain in production and these are not going to go extinct with the coming of the rollups or any other technology that we are talking there are fundamental problems that needs to be solved even if we talk about rollups and so such so these are some of the some of the crucial problems that that always kind of excites me that there are so much more to achieve in this space and that just you know one new technology is is going to of course help a lot but but there's so much more work to be done uh your background is as far as I just heard from your from your kind of the

like department where you're doing your PhD it was cryptology it was actually cryptography but at this point you beca like it's seems like it's way more Cs and architecture and implementation were you more researched and then moved more into the engineering side did it change your role um I think it was of course I had to shift a bit in terms of how I practiced kind of things how I kept on top of the situation but at the same time there was a big engineering team extremely talented engineering team within polygon and I didn't have to go into the nativities of it okay I could stick to things like uh you know BLS

signatures or you know kg commitments and erit coding and things like that as I mentioned ail was one of my core Focus areas but I also got time to think about you know ZK proofs and how we can work on them and so on and so forth so cryptography had always been part of what I was doing but also there was a lot of engineering you know thinking that you had to do because you knew that an idea is not good enough if it cannot be implemented on that production chain which is kind of the Holy Grail of standard that polygon had put up at that point cool okay now I want to hear about the origin story of Avil itself you sort

of mentioned you were already working on an internal project Around Da tell me how that developed and what made you decide then to split out yeah I think from the beginning like me and anurag we were thinking of Da and we were you know writing poc's very simple code just trying to figure out the architecture and so on and then in 2020 1 it made to a bigger team so that we can write a more complete POC and that worked we realized the problems we realized the bottlenecks of the technology we modified the architecture of it and so on and so forth then the team grew bigger and bigger and that's when you will see that aail was launched as

polygon aail from within the polygon org um but at the same time we quickly realize that a DA layer is kind of the fundamental layer around which rollup ecosystems are going to thrive which means that if we are not credibly neutral then it's a problem because competing Solutions are not going to use a d no matter how good or bad it is how secure it is it doesn't really matter if a competing token is the one which is securing your base layer you wouldn't acre value you are actually giving you are acing value to your competitor and such M and those kind of conversations were very clear uh at that point and the

second thing was that polygon always wanted to focus on you know the scaling the L2 story and something like ail which is more fundamental as more like a DA specific L1 it didn't really fit into their portfolio uh that they wanted to focus on right so it was it was clear that if we can build something which is neutral we have to go outside the org and for the org also it made sense just to you know keep it as a spinning of as a separate entity got it and this actually might help explain how cuz how I've understood the project like it sounds like it was first an internal only project like proof of concept it

then had this brand but it was a sub brand so like polygon Avail was almost data availability for polygon primarily and then then you are now a veil outside of that yeah absolutely and that's that's the kind of quote thesis right that a should be at the centerpiece of many different types of rollup Solutions uh irrespective of whether they are you know optimistic whether they are ZK whether they are something else but from within polygon for example there's a deep emphasis on the ZK rollup Tech right and that's why we didn't want to bring an opinionated base layer because

this the base layer should be always be unopinionated although the stacks on top can be completely openion depending on the use case I mean at this point I I want to bring in kind of a competitor Celestia because I've had them on the show to talk about da and I feel like they definitely did a lot of the groundwork in popularizing the term in introducing the concept of like a modular stack and I think in 2021 they're already there I feel like I saw a talk from Mustafa talking about the modular stack in Lisbon in 2021 I feel like that happened so I'm kind of wondering like you're working in tandem to this other project were you inspired by what they

were doing were you working from a different angle were you competing like how did you kind of approach them yeah I think uh to be honest in 2020 itself they had the paper I think vitalik Mustafa and others wrote a paper it was extremely inspiring because we were you know looking at that problem they were talking about a particular solution it kind of all made sense and again throughout 2020 2021 there were a few different design constructions which were coming up lazy Ledger was already a thing in 2021 and of course they gave one of the most promising da solutions that are out there even right now in production so a lot of credit to them for kind of

thinking about the problem framing it that way thinking of solutions actually implementing it and so on and so forth given what we were trying to do at that point again as I mentioned in polygon there was a deep emphasis on the ZK Tech and realizing that the Celestia construction is kind of fraud proof secured uh which is of course efficient but it is definitely you have to wait for a fraud proof because it's an optimistic construction it didn't fit really well with the ZK rollup constructs which we wanted to have at that point in time at that point we were very much convinced that ZK is the way to go and that the base layer needs to be valid Duty proof driven rather than

ZK proof driven and those are the kind of you know that's why we chose not to follow something like a hash based construction but rather to rather to take a kg polinomial style poal commitment style construction which was more you know can can avoid fraud proofs and be more Valu proof driven so those were some of the core Deltas that we like you know knew early on that we wanted to do and that's why our design decisions were different although we were trying to you know solve a similar problem when you say that though does that mean that some sort of like optimistic system like op or arbitrum would it be harder for them to work with

you are you more purpose-built for ZK rollups not really I think the there are two layers that are kind of interacting at this point right so one is the da layer and the other is the execution layer the execution layer and the da layer need to be individually secured for anyone to be able to verify the correctness of their transaction data and so on right so as a user user need to be confident about both that the execution was performed correctly and the data behind the execution is actually available that's the guarantee that a user needs so in optimistic execution constructions like the op stack arbitrum

the execution is you know secured by fraud proofs so they can be using any D and that doesn't matter what D they use they can use a Celestia ail they can use a DSC in fact arbitrum uses a DAC at this point right so what does DAC mean what does that say availability committee okay so there are two layers execution and data availability both need to be individually secured and both of them have either validity proof secure uh Solutions or fraud proof driven Solutions Celestia is a fraud proof driven data availability solution ail is more of a validity proof driven data availability solution similarly

polygon zkm um ZK sync starkware they are more Valu proof driven executions Solutions execution scaling Solutions and arbit from op stack and a few others are the optimistic style Solutions but they each one of them can talk to each other seamlessly there are of course a few nuances here and there but they are not incompatible some things are a better fit than others but we will talk about that maybe later is that when you're going to the application Level like some applications might work better on one of these systems versus another uh it's it's it's more about let's say you have a ZK based solution uh ZK based execution engine and that is when you

decide that you will not want to wait for a fraud proof okay and those kind of systems will not want to wait would not want a ZK proof in hand for execution but had to wait for a fraud proof to arrive for the da to be secured so these are the you know constructions where it it might not make very much sense for a user to have these two solutions pitched together but those constructions are also available today okay in terms of the DAC versus the right now constructions I think today there are a lot of different constructions in production and uh sadly like it is

either a good thing or a bad thing I don't know but many different systems are today in production which might not be extremely extremely secure as people want to believe right but all of that aside something like let's say arbitrum has both a DAC as well as a ethereum based da solution so they have a rollup and which is a optimistic rollup as well as something which people like to call as optimums where there's an external da which is a data availability Comm and an execution engine which is secured by fraud proof so those kind of constructions also coexist so they have

an arbit from one and an arbit from Nova both have different security and cost implications and such so you're saying that there's like ethereum data availability another committee or something that's doing a second version of this data availability I want to find out why there's the two we know that the settlement layer for something like that is also the ethereum base chain why are there two data availability sources why do that no I think it's not about that there are two data avability sources is that there are two different constructions which are running okay so the different constructions make different tradeoffs on one hand you would want to run a rollup secured by

the base layer which inherits the complete Security and that's where you would want to have an optimistic rollup in its final form which uses let's say ethereum as a DA and as settlement right so that's something like like arbitrum one and okay then there is arbitrum Nova where you want to you are seeing that you are already spending you know something like 1,300 to $1600 per MB of data that you are posting on ethereum that is getting to be your main bottleneck that that is where your cost is skyrocketing and that's why you find that there is no other very good da

solution that is present so right now what you do is you set up a committee you allow them to you know handle the data avability part and on chain you verify that the committee has given the vote has signed have had enough signatures that the data behind the attestation or the assertion of EX ution is available so those are two different systems got it and so I I understand what you mean so they could be running they're sort of running in at the same time but in order for like efficiency reasons for for affordability they've created a centralized da in a way I realize it's committee but like it's more centralized

it's not a fully decentralized group that's doing the same kind of sampling I guess that any da layer would be doing any anyways right like they're oh not even okay so then is this what you mean by like it's less secure it's not only that it's not decentralized but it's also like just using a different form of Da yeah exactly so that's when what you do is you send the same data to various different members of the committee and the committee members sign that you know I have access to this published data and I sign it off and on ethereum you just verify that the they claim to have the data right so there is no s there's no sampling

there's no sampling it's a small group of people but that's how it it works in a DSC okay I think it would be really good for us to now introduce da in the way that you're building it which involves sampling I guess I'm assum I'm assuming so yeah why don't we talk about the da system that a veil presents and then we can kind of understand maybe how that's an an evolution or maybe a step up from these dac's yeah so in aille we wanted to create a decentralized data availability based layer and for that we wanted not only a base construction which is secure

and decentralized but also uh a way for light clients to achieve data availability sampling to in order to verify on their own whether the data is avail available or not without relying on the super majority of the chain for data availability guarantees so that's why what we do is we used kg polinomial commitments and erasor coding in tandem to create those construction where the super majority of the chain only decides on The Ordering of the data and creates those commitments whereas the light clients who have access to these

commitments can can do the sampling and ask for openings which are individually verifiable by them and by the order of sampling we also have created a peer-to-peer overlay network of light clients so that the light clients have minimum Reliance on the full nodes of the system the full nodes Act only as the initial source of uh the sampling information but at the same time once the peer-to-peer Network network is populated enough then anyone can ask the peer-to-peer Network to give them samples and they can verify on their own and have a high guarantee of data availability uh of the particular

published blocks going back to Celestia do they have a different kind of sampling I don't think that they have a different kind of sampling there are two major things which are slightly different than what we do the first thing is even after sampling you have to wait for a challenge period for a fraud proof to arrive or not arrive mhm so that to know whether the whether the sampling was done on the correctly encoded data or not yeah so that is the optimistic construction that I was talking on uh about a bit while back and the second thing is that I don't know the exact uh status right now but to to the best of

my knowledge the peer-to-peer light client does doesn't directly sample from the peer to-peer itself they have a high Reliance on the RPC nodes for getting the samples whereas in aail we try to retrieve the samples from the peer-to-peer first rather than going to the RPC for the samplings but that's a implementation detail I guess is just more trust minimization and and less kind of Reliance on rpcs that we are choosing to go for all right I'm I mean I'm going to actually have them on the show in a few weeks so I'll be able to also ask them some of these questions um just to get clarity I want to kind of also ask about igen layer because we had

sham on he talked about building Igan da on top of igen layer base thing that they have the reaking thing do you know anything about that system and how it might compare to a veil I think Ian da as far as I have seen and read the various reports is that it's a DC solution and it's a it's a cryptoeconomic guarantee which they derive from the igen layers AVS systems so it's going to be extremely efficient we are you we are still to see like how many people are going to be there in these committees um how do they work and how do they sign off and so on but at the end of the day there will be again a

smart contract on ethereum which will verify that the committee has given enough signatures the only way of slashing would be things like double signing and such so they do not inherit the full security that an L1 can provide because at the end of the day there are classes of fals which are non-attributable which at the end needs to come from things like social slashing and things like that that only base l1s have but at the same time there are other you know provable faults that you have which are easily verifiable by something on chain which are some of the things that any of the igen lay services

will be able to derive and the cryptoeconomic security is going to come from something like you know already St a e and so on but that will also be opt in and will not naturally kind of inherit any other base layer security as people like to think let's talk about how you do it then so a veil I guess is uh blockchain on it in its own right is it Standalone is it like sort of floating next to the chains that it works on ail is a standalone chain built on substrate framework and we chose kind of substrate because of the various properties that it offers in consensus

systems and in economic design that it has for example you know we can support up to a, validators as of today but it can go up to something like 10,000 validators uh um once we activate BLS signatures and such on the other hand it has fragment election which secures the base layer in a nominated proof of stake uh system that allows for maximum decentralizing the base layer system and keep the centralization risks at a minimum uh at the same time you know there are things like how the babe and Grandpa protocol works together as was

mentioning in the beginning of our discussion about how it provides a hybrid ledger so that you can give liveness as well as strong finality guarantees and then block production using a verifiable random function and things like that so there is a host of different things that we have at the base layer to make sure that it's one of the one of the most secure and elegant designs that we have seen around and that's why we hope that people can be using the D layer not only because it's it's just a very good validity proof driven design but also because it's decentralized because that matters otherwise there there is going to be Les lesser and lesser differences between a

DA and a a blockchain which has high centralization risks oh interesting in researching this I heard another interview where You' mentioned that you originally started with tender uh and then switched just so you know I like with the ZK validator we actually we validate on polka dot and on Cosmos Hub and some other chains we've experienced both of those models as validators and so I understand what you mean when you talk about fragman this is the kind of evening factor of polka dot it makes it very difficult as a validator to predict where you're going to stand in the list whereas with tender Chains It's very very obvious like stake delegated to you is only delegated to you and you can

kind of see the ranking and that's been a really interesting kind of thing to to see from that side um but yeah you decided to go with the fragman polka dot model the other thing I I heard from that interview though is you're not in the polka dot realm you're not a parach chain yeah that is correct we chose to uh bootstop our own security creating a solo chain based on the substrate framework and not join as a par chain to the poar relay chain at the same time we didn't really start with the tender or the cosmos SDK because already knew as I mentioned one of the heal layers of polygon POS is built on tender Min and okay Cosmos SDK so we knew the

experience there so what the what the pros and cons are and so on WE of of course had other considerations like we had a rust based code base so it was easier to write it in substrate and we didn't want to Port over in go and things like that but there are many many different considerations which come together but yeah largely there were two options to us Cosmos SDK and substrate and we chose substrate interesting it being built on substrate though if you wanted to would you have like access to things like xcm or any of the other Tooling in the polka dot world if you wanted to like connect to it the answer is it needs research because we have made so much changes to the

fundamental block production engine the header structure because it's a it's a fundamentally different chain right so one of the things that I keep focusing on is that sometimes it feels like anyone can create a d Chain by forking off any of these sdks and just creating another chain which has very lowc cost you know call data or something but the that is not true because you need to make fundamental changes inside the block production engine inside what you keep in the header how you construct it how you sequence the transactions how you encode them and so so on and so forth so at this point of course the tooling is something that we already use right now

like we get access to the you know the Explorers the apis the indexers and everything of the pulot ecosystem so that's a that's a good thing that we have a lot of tooling of the poar ecosystem that works as it is with us but at the same time getting connected to a particular pogon chain using something like xcm which is deeply embedded inside how the verify verification works on the relay chain might be difficult to achieve but I haven't looked at it deeply that matches what I would have expected there that it's it seems like xtm right now really functions primarily in the polka dot World kind of using the relay chain is that Central Hub in your case then like

the substrate that you have this is sort of the interesting thing always about open source technology right open source Stacks is like you've altered it I guess it's a different substrate do you feed it back into substrate somehow like do you kind of still add to their libraries or like the maintained parody libraries are you kind of just like on your own Journey with it I think it's a it's a conon that we were even discussing yesterday because uh one of the things that with substrate is that they have changed from a substrate specific repo to a poot SDK monor repo for all their tooling related to substrate and and so on and we use substrate like a Delta on top of

substrate that we maintain our on our own but we haven't tried to Fork it off because then it becomes hard to contribute back and as well as you know making sure that we are up to date with the latest of the changes because it's an awesome community that keeps on bringing Innovation into their chain and we want to be of course we helping them contributing back to them and so on so that's why we we are right now at that juncture where we are moving from having substrate as a dependency to PO SDK as a dependency and we were thinking whether we should use paarat SDK fork or not but yeah roughly speaking how we will do it

is that again we will keep pocon SDK as the main dependency we will try to work on it off it try to contribute back as much as we can um and we have already started kind of doing that using the you know the verifier the bridging that we are contributing to the P Community um it's funny when I hear about not exactly da but just if you look at the models we now see they sort of mimic that polka dot Reay chain with things coming off it and I know I mean the Celestia model that I remember that they've presented also sounds a little bit like that ethereum with rollups now looks a little bit like that but I think when they created it remember they're they're planning it many you know many

years years ago I don't know that they conceptualized it as a DA layer exactly in the case of a veil though do you see a veil as sort of a central Hub which you know rollups will link out of or do you see it more as a kind of added tool to existing rollups on another Hub do you kind of know what I'm saying like you know this Hub and spoke where like there's a center and then there's the rollups that Branch off it I think that is one of the fun things to kind of think of in this explosion that we are seeing of rollups I think it will be bit of both it's very hard to predict which one will be the dominant one but

it's going to be always a bit of both so for example there are constructions like Sovereign rollups and based rollups which will always kind of you know live of the D layer because they fundamentally work on a central D layer and that act as their source of Truth yeah for any rollup to be honest da is the source of Truth whether you think of it as a adoc service that you know you can plug into or whether you think of that as the base layer but because execution proves do not work alone they have to be proven over sequences of data or state deltas and it is important that the state Delta is actually available

and that is the you know fulcrum over which the execution proofs are built off and that's why da is always going to be part of their security modeling that they will have to do it's now a question about what is there maybe the canonical bridge that they decide right I think uh some of the discussions and the controversies and the 2 Andro on crypto Twitter is sometimes about what is a rollup and how do you define a rollup what is its canonical source of truth how do you determine the state of a roll up and so on and so forth I think there will we will see like right now you will see that the dominant strategy is to keep the canonical bridge on ethereum because ethereum is such a well-known

settlement layer with all the users and the liquidity and such and that we will continue to see because that will be the canonical bridge for most rollups but at the same time there are other constructions which will come where the bridge is less important there will be app specific constructions which will come and and so on which we will continue to keep on seeing how things evolve and uh how to think about it is more like a mesh rather than a how and spoke I would like to say because there are these constructions where a rollup talks to two different layers and then there is an L3 built on a particular rollup and then there are you know

Bridges which are through some settlement layers some like want l2s to be settlement layers some only rely on the L1 to be the final settlement layer so there's a plethora of constructions which are possible in this space so it's yet to see how things will evolve in my opinion so far we're mainly talking about like the data availability side of this so this is the ability to sample the fact that like data is available but what about when we do kind of think of a rollup coming off of a DA Hub often you need also the consensus the consensus mechanism like those rollups may be using that in that model so does a veil have both da and consensus that a rollup

could use or in the case of aail are you expecting these rollups to live on another form of consensus like a like a consensus Hub and kind of doing it elsewhere yeah I think ail just to answer it straight it has both ordering and data availability and to kind of go into a little bit deeper is that there are two aspects to the transactional data that someone is sending the one is the ordering of them and the second is the data availability as I mentioned the sampling works great on the data availability guarantees because once you have the ordering fixed and committed you can then sample that parts of the

data are available or not and that's why you have a guarantee that the entire data that was committed to is available you still need the consensus which is the cryptoeconomic guarantee that the ordering was set right and that you they cannot deviate now from that ordering so now once they have committed to something they cannot do a double signing and then Fork off the chain and then your commit like the committed ordering is different which means your sampling is now irrelevant so it's interesting the way you describe it so in in your case like consensus here is just about the ordering of transactions I guess maybe it's always been that but for for some reason I thought it was bigger but um but yeah like at the same time the ordering that

you're talking about this is meant to be like the canonical truth this is the immutability this is the sort of blockchain aspect but each one of the rollups may have their own ordering on their side so they have like sequencers that are putting things in order potentially so the ordering you're talking about though is on just on the da level like the Avail level that you're doing the data availability and then making sure that there's something immutable about the way that that's being built absolutely absolutely I think the sequencers uh in the sequenced rollup world will always determine the ordering within their existing rollup there are shared sequencers where multiple rollups will uh allow their ordering to be

determined by the shared sequencing engine and then there are based rollup constructions which will rely on the D to determine the canonical ordering for their transactions and users are going to directly submit to the base layer rather than to a sequencer or a shared sequencer so there are many constructions which are possible in this space with different varying levels of guarantees of censorship resistance of liveness and and so on and so forth got it the things that are actually being ordered in the case of a veil what are they are they just commitments from the sequencer of a rollup onto this new chain or yeah like what is the actual items that get written it's actually

data blobs so sequencers or individual users they submit data blobs to ail ail is a extremely dumb layer it doesn't know what it is dealing with it takes all of these data at pH value as Blobs of transactional data and then just orders it within its block ex like the block ordering engine and commits to the data blob so that's all it does either either the sequencer submits exact blobs where they have transactional data might be compressed or state Deltas which are also much compressed and St stuff or it can be you know someone like a user directly submitting their transaction as

a data blob which may be incorrect even in the after the ordering is done in this case though does does the security of a veil then also depend a little bit on how valuable the network is like in the way that we think of like execution like ethereum or what have you like this sometimes people will say security but what they actually mean is like market cap because it would cost so much to buy two-thirds of the validator set or what have you in this case are you still working under that model like say say you don't have a big U market cap if someone bought those validators what could they do I guess this is the question yeah yeah I think exactly like

that is essentially the security of any POS chain or for that matter any blockchain network is the cryptoeconomic guarantee that it takes to overcome the majority of the network is how typically security is defined of course there are many ways to Define security but cryptoeconomic security is the cost to either halt the chain or take over the chain is how I like to think of it and then for aail as well um if it doesn't have a high enough security then you know as you said a state actor can come in take over the complete uh validator set or majority super majority of it and then revert the ordering that was

present right so what it can do is that the existing validators can create a chain and the light clients would be sampling on that fork and be sure that the data is is available but then later the the super majority can revert back to Fork off to another chain in which it has a different ordering which will then be incompatible to the light client who has already maybe processed like agreeing that the data was available and the execution was correct so that's the kind of attacks that is possible for the rollup itself like since you said it's just Blobs of data it's kind of like is there any sort of you know remember I'm coming

from ZK worlds where like it's sort of it's usually private or like hidden or something um but in this case if they knew where the blobs were like would it almost be like an application running on the L2 deals in some Financial trade and because it's been able to corrupt that underlying da layer it can reorder which would allow them to have some Arbitrage opportunity or like they get a better better trade or they sandwich or they do some weird me thing like is that sort of what we're dealing with in terms of like the scope absolutely so think of I would like to think of it like let's say you have a financial application on ethereum

and you say you do a transaction where you send some assets to me right when is it that you will decide that this is final this is going to be done I would consider them to get the services that they paid for or something like that um you would have to wait for the finality of ethereum right let's say 12 minutes you wait for that of course you wouldn't wait for that long you would take the probabilistic finality and be sure in maybe a few minutes but if you want to be very very sure you want to get the full backing of the cryptoeconomic security of ethereum you will wait for that time and then determine that it is final so it's done but then if there is some actor which can corrupt the

entirety of ethereum of course impro but if someone is goes ahead and does that then they can now revert the payment that you done and maybe do something else extend it back to them or whatever right so that's the kind of same problems which can have happen on rollups as well if their ordering can get reordered except that there's so many layers between it I guess this is what's kind of complicated to me which is on the ethereum example it makes sense because they're looking at those transactions but in this case there's a DA layer with a blob that comes from a sequencer that has another network

attached to it and so like is it so transparent that like someone could still map it back to that and like corrupt the application that lives on the L2 through affecting the da layer there are two ways to answer this right so the first way to answer it is okay let's see how does ethereum protect against these kind of attacks right so what you have to do on ethereum is that you want to be running a full node in order to determine what is correct and what is incorrect just because someone can reorder and revert the finality doesn't mean that the full nodes are going to accept that reverted finality and the second Fork that has been

talking about if the full nodes determine that this is not the canonical ordering that I believed on and the finality was reverted on their Fork because it's a finality reversion they would actually slash a large amount of network and keep on maintaining a minority Fork which they will follow okay it doesn't matter the cryptoeconomic security of the total chain because a lot has been slashed but they will still go on and keep maintaining the uh minority Fork it would also kind of you know slowly leak the stake of the Mal ious actors so as to the active stake being able to recapture the maximum stake in the in

the minority Fork as well so there are different ways in which POS chains protect themselves from these kind of attacks okay and that's why you kind of rely on running a full node uh in order to know whether ethereum is working correctly you just don't rely on the ethereum super majority for everything for these kind of attacks and similarly in aail what we want to give our clients the guarantee is similar guarantees but by running light clients and that's why in light clients they will also do the same they will do the sampling on the canonical fork and if the canonical fork in any time reverts the order then it will stop following that canonical ordering and it will keep following this

minority order here okay and that's the social layer of any blockchain system is when these kind of attacks happen the social layer is supposed to K kick in and that's one of the things which you know people sometimes use or abuse in theoretical conversations like this but in my question I'm imagining that all of those things fail y I'm literally just trying to understand like how nuanced an attack could s could an actor get some financial gain with all of those levels with like the sequencer and the blobs like this is where I'm just kind of I'm kind of confused about how an attack like that

looks if like say let's remove all of the guarantee like all of the good things like say it's a tiny little chain it's only half built it does Da but like how would someone attack it is actually the like what what could they actually do I think they can go and attack the core rollup ecosystem around it that the da chain is getting used for because that's such a fundamental you know section of this entire ecosystem that we are talking about now with other layers on top it makes things much more nuanced for example you talked about having let's say a settlement on ethereum whereas this super low security

chain being the da and then ethereum depends on how ethereum is going to verify the attestations which come from this D if ethereum is going to only listen to the super majority then these attacks are then viable right because your social layer will kick in but it will kick in too late and it doesn't matter because your settlement layer only listens to the super majority and doesn't care what your social Fork is going to look like for example the similar uh way of looking at ethereum is that I can maintain a minority Fork but if the all the exchanges of the world doesn't care about my Fork then my Fork is not valuable right I can today only

take the entire ethereum chain Fork it off and claim that that is my that is the default eum that's that's all mine everyone's ass is mine right but that doesn't mean that all the exchanges all the settlements of the world actually agree to that so it would at the end of the day it is a complex you know social game that is going to get played in these kind of attacks interesting and I guess that is the the big thing is that there's this settlement layer that is separate from what you're talking about which also has its own role um in actually like if there was an attack it would somehow have to be incorporated into the the attack one of the reasons though I ask this question I realize I'm asking you to like predict a

worst case scenario and I'm sure there's lots of reasons why it wouldn't happen but in terms of the value of a veil if you're working with networks that are worth more I guess this is sort of a question like Can it can the security of one network if you are securing things that are so much more valuable does that change the economic game for an attacker somehow can it still secure really valuable Chains No I think the answer is very nuanced but if I had to answer it very suly I would say yes definitely right so the answer to that is whenever a rollup is using some base layers for whatever reason let's say for da for

settlement it inherits the security a as a function of these layers what is the exact function I like to think of it as the minimum of the two right but there might be other you know debates about how people would like to frame because security is also very nuanced like what is it that it actually fails is it the liveness the safety uh sensorship resistance things like that so there is a plethora of different things which we have to consider but I like to think of it as definitely it has to be very secure for someone to be using a d otherwise it's a it's a problem because

you inherit the security of all the base layers that you work with what if you have a really strong GA but a really weak settlement layer would you say that then the security is sort of that of the settlement layer I would say yes and no as I mentioned this is Nuance super Nuance sorry super nuanced but at the same time let me okay let me try to break it down a bit right so let me try to break this down a little bit so as to make sure that we are propagating the right Notions to the end user because someone listening to this might think that oh God I am now talking about another layer in another chain which I don't know how the cryptoeconomic security is and so all my assets are going to go for a toss the actual answer

is that it all depends on the design and the architecture of the of the rollups but in an Ideal World when the rollup uses a DA layer and we are talking about light client based samplings then a user is going to do their own sampling to know whether the data is available or not MH under those conditions the user have the chance to verify da on their own and for the settlement part in general how we like to think of things going forward is that this user is going to verify the proofs of their own like for example we are already working with

wallet teams to embed a Das light client of ail inside the wallet as well as a ZK verifier inside the wallet okay so if you think of it then people are relying on ethereum to do the settlement on their behalf M but actually users are powerful enough in this future world to actually verify both the execution and the data availability inside their wallets and only rely on ethereum for L2 to L1 bridging and not for all the L2 uh interactions that is happening because that is essentially verifiable and what that really means is for someone like you know Stark net who we are partnering

with and so on is you know they publish proofs maybe 6 to 8 hours but in these kind of designs the users can get a very high finality guarantee because they can do datail sampling which means they know the canonical ordering and the data availability as well as they have a ZK proof which means that they can verify all the l22 transactions and then after 6 to 8 hours only ethereum gets convinced but the user is much convinced much before that I see that was actually one of my question questions was do you use ZK this is a separate construction this is like a wallet that's using a lot of different things but this is sort of the future you see how how advanced is

this like who builds this wallet does it already exist or is this like a theoretical thing this is one of the RFP grants that we have as part of a Uncharted it's partially built it's uh like the Android client already Works roughly but uh that many different things to actually work on we are actually also working with a few other wallet providers people like sub wallet we are working actively with in order to have these Das light clients inside them and yeah it's a work in progress because there is a lot of different technologies that I you know right now spelled out but all of them working in a constant

environment like in a mobile or in a browser extension needs a little bit of you know working for example I think one of the questions which you were asking is whether we use the ZK technology or not the answer is we do not use the full ZK but we use the kg commitments which are part of a few ZK constructions as part of the commitment scheme that they use and in those KES commitments there is a lot of You Know Field operations which we have to do inside those wallets which might be inefficient when running inside let's say wasm and such and also I re I talked about the peer-to-peer design that we have for the light clients and peer-to-peer operations are

notoriously hard to do inside you know browser extensions and such because of security reasons and the limitations under enclaves and such so there's a lot of different things which need to come together for this Vision to actually happen but the basic building blocks are getting built and we are actively working towards building one just going back to that sort of fraud proof versus I mean I think you call it the validity part of a ZK proof one of the criticisms in the past with ZK rollups was sort of latency and timing like that it would take longer to create these proofs does that also affect the kzg proofs in any way yeah I think uh the kg proof we had similar reservations but at the same

time that is one of the reasons why we wanted to do an early POC and check this out and so on in inside our test environments like we can create blobs like blocks of up to 128 MB with ease inside one block period at that point you know the block propagation and things like that dominate over the kg commitment generation so you know the commitment generation is extremely fast we are not as I mentioned not doing the full ZK route of the entire of what a ZK algorithm does today but we are only taking the small commitments scheme and there has been huge improvements done in

the performance of this Cas commitment generation schemes cool you mentioned a few of the people that you're planning on working with where you already have Partnerships I know you have quite a few so can you share a little bit about like you you know you started from polygon you've gone past you're you're out of polygon in a lot of ways is polygon still going to use a veil I think all the major rollup Stacks are are going to use aail and again I'm saying that not because we have announced all of these collaborations but because I believe that we will keep on seeing that the da layers are going to be you know be used by all these different chains across

different solutions that we provide um in terms of you know polygon yes we already have a zkm fork that we maintain which uses aail and we have a public endpoint that anyone can use today to test out how the experience looks like how the blobs are getting submitted to our incentivized test net and how they're getting verified on ethereum sepolia and such um there is also you know work that we are doing with the cdk ones that is you know in production we will take a look at it we will talk about how we are going to jointly collaborate on that but things like you know stet we have already

announced our collabor for the Mad app chain world again Madara uses something like substrate so it was purely easy for us to make sure that uh we are fully compatible with that uh in terms of you know others like we have an OP stack Fork which anyone can use today uh to use with ail and op stack um and then we are also you know working with the other Stacks to kind of make them compatible so in the end we will have all the major rollup Stacks but these are all evm compatible or Beyond but there is also things like you know ZK VMS that we are working with like Risk zero like the ZK

wums and and so on where we also think that huge progress will be made in the coming days about how people are going to not think about too much when depl playing their own roll up because it would be so easy and so tailor made for their app wow that was actually one of my questions was other VMS nonm do you have to change something to deal with that or can you keep the same system as part of oil as I mentioned it's a very dumb layer it doesn't really know anything about the execution engine but at the same time I think we don't have to uh change anything but typically the different things change for example

transaction size is how big does a transaction look like the the structure of them that changes for the execution engine but not for a will there are other stuff like for example there are sovereign rollups and such where some of the design decisions also play a key role but that's not for the execution engine style got it do you think any anything over in salana will ever need da do they have rollups I don't know I feel like they're it's like a ecosystem I knows so little about and weirdly I've mentioned them multiple times in the last few episodes and I don't know why they seem to be the Talk of the Town at the moment exactly I think uh I mean Believe It or Not uh we really like the Solana

VM and we have been actively approached by Solana ecosystem applications who want to you know tap into the ethereum ecosystem right now then they want to use the you know ethereum user base the liquidity that is there and then they're exploring uh some of the rollup Stacks that are present today right and that is because the svm is extremely extremely efficient in terms of you know its performance and such and that's why you will see a few different uh projects which are trying to use the svm as a execution engine oh wow but then

ethereum as a engine and these kind of you know interesting kind of architectures are going to come up more and more that are going to be problems because this also means that the svm by itself has a lot of chatter which means that the transactional demands are going to be much higher than the ethereum ecosystem roll of Demands and such so scalable da is going to be one of the fundamental things that this entire ecosystem is going to need fascinating pral thank you so much for coming on the show and letting me ask all of these questions about like it's these edge cases for da layers I realized that we you know at some point just went off topic a little bit like

into the you know what could someone do if they had like unlimited money and it was a different world but thanks for kind of like walking me through that because I think this is something even kind of testing out those edges those like very unlikely cases it just kind of gives a bit of a sense for for what this is the power of it yeah what you need to build around it as well no absolutely I think those are some of the edge cases for which we are also I wouldn't say very prepared but we have designed it keeping them in mind so that even the super majority and stuff can get compromised and such but thanks for asking me the questions because I don't get to you know talk about them a lot cool all right thank you so much for coming on the show I want to say thank

you to the podcast team Rachel Henrik and Tanya and to our listeners thanks for [Music] listening