Hi everyone!
I'm @johncantrell97 and I've been working on and around Bitcoin for over a decade now. Most recently I've been working on Sensei as part of a Spiral grant.
Sensei
Sensei is a lightning node implementation based on the Bitcoin Development Kit and Lightning Development Kit projects. Sensei can run modularly and share certain components (networking graph, p2p gossip, chain data monitoring, etc.) with multiple nodes which allows for extremely lightweight nodes.
If you have use-cases that require running lots of nodes (one per user?) then Sensei might be a great fit for your project.
Brute Forcing
You might have also heard about when I orchestrated a cloud gpu farm and checked over 1 trillion mnemonics in 24 hours to win a bitcoin.
Entrepreneur
I've also founded, bootstrapped, and grew a startup to over $2M in annual recurring revenue before selling it for an 8-figure sum.
AMA
Feel free to ask me anything about:
  • bitcoin
  • lightning
  • sensei
  • spiral grant process
  • brute forcing
  • starting/running/selling a company
<3
what is your assessment of the pace of bitcoin development over the last decade?
has it met or exceeded your expectations?
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I think I had hopes that the initial sidechain proposal by blockstream would have panned out. I think that would have lead to rapid experimentation and development but it never came to fruition.
I haven't looked enough into BIP-300/Drivechains but they offer a similar promise. I'd love to better understand the arguments against it but in general would love to get something like it eventually. Perhaps the best we can do are federations like liquid and fedimint though.
With that said, I am generally a proponent of the 'take it slow and don't break things' approach when it comes to bitcoin. It's definitely not the way you should build a business but when it comes to a once-in-a-human-history project like bitcoin I'd prefer to make sure we don't screw it up.
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Chesterton fence
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What's something you disagree with nearly all Bitcoiners on?
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Hm, this is a tough one. I'm not really in touch with a lot of bitcoiners so I'm not entirely sure this is a major disagreement but it definitely feels like one.
I think in order to scale non-custodial bitcoin to the entire world we will likely need to scale the block-size at some point. I think something conservative that grows along-side the growth of technology (bandwidth/cpu/storage/etc) might make sense.
Otherwise we probably need to be okay with a significant portion of the world using centralized or federation-based custody.
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Bigger blocks?
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what was the process like to obtain your spiral grant?
how do we get more companies lining up to support bitcoin development?
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I knew I wanted to work on/with bdk and ldk so I wrote up a proposal that outlined roughly a years worth of work and submitted it to Spiral. There was a little back-and-forth where they explained the process and expectations a little more clearly and could get a better understanding of what I wanted to work on.
They were pretty flexible as my plans did end up changing quite a lot compared to what I originally proposed. Initially my plan was to focus primarily on DLCs but building out a lightning node (sensei) with bdk+ldk ended up being the core of my work.
I hope that as companies realize how important bitcoin is for the world (and their company) that they will prioritize funding the ecosystem as a core part of their business as Block (and a few others) have.
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Could you share a copy of your proposal? OR resources you recommend for drafting one?
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Sure, they shared it in the tweet thread when they announced the grant. The original document is here: https://docs.google.com/document/d/1--5Hh9zi2kKEZrvhAhWP_Ge9oUVPm00wcMQ40arYhoI/edit
Like I said though, my work has greatly deviated from the initial idea.
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Thanks so much!
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What do you think are the biggest obstacles facing Bitcoin and Lightning right now?
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I think in the short term the biggest obstacles are that of education. A lot of people don't understand the current monetary system, the problems with it, and why bitcoin is a better solution.
In the longer term I think there are lots of scalability issues that need to be figured out if non-custodial bitcoin for the entire world is a goal of the project.
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John, it was a pleasure to meet at BTC++, glad you could make it out.
If you could attribute your success to a principle, or a few principles, what would they be?
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Hey -- was nice finally meeting you (and lots of other people!) in person at btc++.
I think one important thing that helped me succeed was to always try to align my work with my interests. When you are naturally curious and interested in what you are working on it makes the difficult times much easier to persevere through.
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I could not agree more. Perseverance was a principle I was recently meditating on, so it's interesting that it was your response.
When people have asked me how to get involved, since the very beginning of my entry into the Bitcoin space, this has been my thought:
Make two lists. 1 of things you like doing, and 1 of things you're good at. If you like doing it, you should be able to do it for a long time, and if you're good at it and do it for a long time, you'll likely find a way to make money doing it eventually.
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  1. How did you get into Bitcoin?
  2. How did you go about learning to develop with/on bitcoin?
  3. What do you feel is the hardest part with running a lightning node?
  4. Top 3 current favorite books?
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  1. I can't actually remember where I first stumbled upon it. I think it was maybe on reddit? I was already aligned with the censorship/seizure resistance mindset and was probably on a path to become a gold-bug before discovering it.
  2. I initially started with just interfacing with bitcoind via the rpc apis and had built a binary options / futures market prototype with it. From there I think I used Jimmy Song's programming bitcoin as a reference for building and understanding bitcoin more deeply. I've also been through aantop's mastering bitcoin and mastering the lightning network books. I also participated in chaincode's lightning seminar and highly recommend the self-paced content should you have the time and motivation. I tend to learn best by having a project that I'm excited to build and using it to motivate me to learn what I need to in order to get the project done.
  3. Hm, it sort of depends on why you are running a node. If it's just for you to be able to make lightning payments somewhat regularly then I don't think it's that difficult at the moment. You could get away with using a mobile wallet pretty easily in that scenario. If you are a merchant/business who needs to receive lots of payments then managing your inbound liquidity is probably an important challenge to tackle.
  4. I don't really read that much other than bitcoin/programming books. I'm currently doing another read-through of Mastering the Lightning Network at the moment alongside the bolts to make sure I really understand everything. As for fiction, I'd recommend neal stephenson (cryptonomicon and snow crash?).
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111 sats \ 1 reply \ @sb 20 Jul 2022
How can we simplify complicated concepts to educate more people, to better generate mass support for excellent projects such as yours?
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I wish I had the answers. I think there's a few levels of education needed depending on the target audience. There's a pretty significant lack of technical/developer level education imo and is an area I hope to contribute to in the near future. There's a decent amount of higher level education around 'why bitcoin' but it's not widely distributed.
I think people can help by focusing on a smaller niche of the broader ecosystem and creating focused content. We'd probably then need a mechanism to organize all of the content into a better structure for mass consumption. Open to other's ideas!
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There is a growing space of turnkey lightning nodes (on the hobbiest end, you have things like umbrel or raspiblitz; on the SMB and eventually enterprise end, you have managed node providers like voltage or opennode). Where do you see Senei fitting in the market? My 2 sats is that Sensei is going to be something like: "a turnkey lightning node that is highly customizable so can end up in places that more monolithic offerings can't fit, like being embedded in applications" Is that how you see Sensei, or is there something different that you're aiming to achieve?
Thanks!
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I think maybe the most 'obvious' fit for Sensei could be as a completely open-sourced greenlight alternative (though I think they have plans to eventually open-source the backend).
Another interesting use-case for Sensei might be for businesses who conceptually like the idea of LDK and have plans down-the-road to require a more customized lightning experience but don't have the resources to start down that path today.
They can start with Sensei (a LDK based node) and easily migrate their entire infrastructure to their future custom ldk based node without having to 'start over'. They can migrate their existing channels and funds without real downtime.
I think it's early days for Sensei and I'm confident it will find its niche as its feature set gets more developed. Stay tuned :)
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Makes a TON of sense. Thanks for the reply!
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selling it for an 8-figure sum
Were you wealthy prior to this exit? If not, how has becoming wealthy changed your life?
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Nope, not at all. I had a decent salary as a software engineer but started out at 22 with a couple grand in my bank account from odd jobs I worked at in college.
The main thing it has done is free me to completely focus on what I want to work on without worrying about my salary.
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Are there any downsides to becoming wealthy, or is it all upside like we all imagine it is?
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I'm still sort of adjusting to it. I haven't really changed my lifestyle at all. I drive a minivan (no lambo here) and live in a modest house. At this point I can't really think of any real downsides.
I guess there's some new 'problems' of how to manage the money so you don't lose it. Luckily we have bitcoin for that ;)
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lol I drive a minivan too
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ha! that's awesome.
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I've had my eye on a Honda Odyssey for a few years now. Someday...
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lol I'm really happy with my Sienna.
Nice work! But I have a real question about Sensei What is the advantage of Sensei compared to a custodial projects like lnbits or lndhub? Since Sensei host the user nodes, it's custodial, so why I would run sensei, pay to open channels on every client nodes (or client paying to open channels) when with lnbits I can manage only 1 node and all users can use my channels? I think I don't get use-cases for Sensei yet. Thanks!
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It's a great question. With custodial Sensei and use-cases like you describe lnbits/lndhub are probably better solutions.
We are working on integrating with the VLS (validated lightning signer) project to enable remote signing for all of the nodes run on a sensei instance. Once this lands you'll be able to spin up your own personal blockstream greenlight alternative running entirely from your own instance instead of relying on blockstream's servers.
There are likely some other use cases, maybe in gaming, where you (as the game developer) don't want to deal with the regulations that come into play when you are custody'ing bitcoin and so sensei w/ remote signing might be a good solution.
Even without the remote signing, there might be some research-y use-cases around simulation/testing different network topologies where you want to simulate and control thousands of nodes easily.
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VLS is an awesome news, it can provide a bunch of new use cases in the future Thank you for this answer
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Hi! you are the guy behind www.theworldcomputer.com?, loved the idea and I hope that you(or anyone else) eventually could built something like that.
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Hey! Yeah that was a project I put together for the impervious hackathon. It's still unclear if it's really a good idea to use lightning to move data back and forth like this does. In reality I'd love to find a way to do the same thing but just use lightning for pay-per-execution. I think you can pretty much do this type of thing with LSATs but would still be nice to build a little framework around it. I'd also love to find a way to enable 'trustless' code execution where you can pay someone to run the function for you but have proof they didn't modify the code that is run. I think there's a way to do this as some future extension of ideas used in DLCs.
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Discreet covenant?
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I'm probably late here, but I work for a company that accepts donations for non-profits on the legacy payment rails (credit/debit + ACH).
How likely is it that Sensei would be a fit for my organization to be able to allow our partner orgs to run their own nodes to accept Bitcoin donations over Lightning, and giving us some level of insight into each of them, while actually remaining non-custodial from our end?
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Once VLS is integrated it's probably a workable solution if you need to be non-custodial. The problem is that the partner orgs would still need to run some kind of long-running daemon (the signer) so if they can do that they probably can just run their own CLN/LND node.
I guess once some of the LSP functionality lands in Sensei then there might be an argument that you could essentially manage liquidity for their nodes for them without them needing to deal with it. They'd still need to run the signer though.
I'm not a lawyer but it's also possible even running Sensei in custodial mode (keys are in memory on the machine) might not count as custodial in the legal sense. You can set it up so they still log in with their own username/passphrase and this passphrase encrypts the seed on disk so you never have direct access to it. This is the voltage model and they largely claim to the non-custodial (as far as I know).
I guess it largely depends on the exact requirements?
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That's a good point on the signer.
I believe what I've heard Graham and Nate from Voltage both say, and what is listed in one of their blogs Nate wrote, is that they are a "non-custodial, but not trustless" service.
Ultimately, we serve over 14,000 organizations worldwide with a native mobile app on Apple, Android, and in some cases tvOS and Roku. It'd be great to turn on a Lightning interface in our ~100 million apps currently installed on peoples' phones around the world. So they could not only donate Bitcoin to the orgs whose apps they've downloaded, but be interoperable with any other Bitcoin + Lightning wallets for p2p.
On the non-custodial side, it'd just be nice to do this in the spirit of Bitcoin's original ethos. But we would also have to balance the need for nonprofits to issue tax docs for deductions from the donations if their jurisdiction allows for that. As well as their need for liquidity.
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Thanks for taking the time to answer these questions! I'd like to own my own business one day, but I'm not sure how to go from idea to product. How did you go about getting the first customers for your startup?
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Best way to go from idea to product would be to try to come up with a way to cheaply test your idea. It could be as simple as setting up a type-form or some other way to survey your potential customer base to find out if they'd pay for whatever product you have in mind.
I got my first customers the old fashioned way by picking up the phone and calling them. Since we initially were focused on merchants accepting bitcoin (bitpay was mainly only option back then) we were able to find a list of bitpay merchants and looked up their contact information on their website.
After talking to enough of them we learned they didn't really want the initial product but we did learn a ton about what they wanted. We collected and reflected on all the feedback and we were able to steer the product in a direction that some of those initial phone calls turned into our initial customers.
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Thanks for the insight!
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👋 Hi John thanks for doing this AMA. In your 10 years working in bitcoin what was the hardest obstacles to overcome during bear markets?
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I try not to focus too much on the price. I believe in the same set of core principals that are unrelated to the actual day-to-day price of bitcoin. I also focus most of my efforts on making sure I am always learning and building.
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Can you tell us more about your first startup? What problem did it solve and what was the most surprising thing you learned while building it?
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It actually started as a bitcoin company that ended up pivoting away from btc in 2014 because our potential customers didn't seem to care about bitcoin or even knew what it was even though they were accepting it via bitpay at the time.
At the highest level we were helping merchants sell more goods by building better relationships with their customers. We were able to align our revenue with our customers so we earned more the more we helped them grow theirs.
I'm not sure if it's the most surprising but one thing I learned was that it's okay to enter a market that has competitors (and is often a good sign if others are doing it) as long as you have a way to differentiate yourself. Initially we followed (i think, paul graham's?) advice to do things that don't scale. We provided manual customization and other 'enterprise'-like services to smaller customers and made sure they were happy with us as a way to bootstrap early revenue.
Eventually we were able to split the business into one that offered both a self-service and more enterprise services.
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Great AMA. Thanks for all that you do. I can feel the sense of humility but just reading your answers
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Thanks! I always try to stay humble so it means a lot to me that you said that.
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This post was featured on This Day in Stacker News.
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13 sats \ 1 reply \ @Ge 21 Jul 2022
What is your favorite btc, book, fav non btc book, favorite book that helped you in your building journey. and what is an important thing that you learned that you wish you could go back and tell your younger self?!
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I haven't actually read many btc books actually. I only have read the more technical ones (programming bitcoin, mastering bitcoin, mastering lightning network, etc). Since I'm largely focused on lightning these days I'll say mastering lightning network is my favorite btc book :)
Non bitcoin book, I guess I have to go with cryptonomicon since it's where my pseudonym comes from.
As for my building journey I don't think there's really a book I would recommend there. I think I've learned way more by actually building and then reading and watching docs/guides/tutorials/youtube to help get me unstuck.
Hard to pinpoint something that I would want to tell my younger self other than to mine bitcoin in 2009. I don't have many regrets in my life thus far, things have worked out pretty well.
I think maybe I would have said to not spend so much time playing video games. While I think they ultimately lead me towards becoming a software engineer, I probably spent way too much time with them when I was in middle/high school.
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What are the chances of Sensei getting hosted channel support? (https://fanismichalakis.fr/posts/what-are-hosted-channels/)
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I'm not too familiar with them at the moment. It sounds like they can potentially provide a slightly better custodial experience so it probably makes sense to add support to sensei for them. Will look more into it soon!
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Hope you like what you find! Seems like a good fit for uncle Jim setups. A bit more lightweight but fraud can still be proven.
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I don't love price predictions but my conservative estimate would be for $500K by 2050. I think at a minimum it replaces the market for gold as sov.
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See you in Kinakuta 🏝️