Reminds me of this classic war story: https://medium.com/@amanat361/shamir-secret-sharing-the-stor...
which is in fact by Max Levchin: https://max.levch.in/post/724289457144070144/shamir-secret-s...
How Shamir's Secret Sharing Works
71–80 of 88 posts
Re: How Shamir's Secret Sharing Works
#72Re: How Shamir's Secret Sharing Works
#73Earlier quoted context omitted.
I’ve been noodling over this exact business idea for a couple years! Part of my value prop was to make ops scale down to as close to zero as possible by having the encrypted data and most of the front end for accessing it live in S3 objects (or some similar mega-cheap object store). Aside from that, all you need is the dead man’s switch mechanism. And the secret fragments would live on QR codes that bring you to the…
Indeed, that's precisely why I decided to ditch out of the subscription model and went into one time payment method, did the math and it made sense that I don't need a very heavy system apart from supporting the dead man switch trigger Wrote my thoughts about that here: https://eternalvault.app/blog/why-we-are-adding-lifetime-pri... And it feels good to know that there are people out thinking about this, makes me hap…
That’s great, and exactly what I was thinking. In fact, you have to wrestle with the fact that if it’s too cheap, people won’t trust it.
One thing I had been thinking about was that it’s important to be extremely open about the algorithms and infrastructure required, with a very transparent whitepaper on how it works (enthusiast level discussion of the technical details) and how you have designed the company to be extremely sustainable. I think your job is to convince people of two things: 1) this actually respects my privacy in a way I can verify myself (or lean on the technical expertise of other outside observers), 2) this company actually has a chance of surviving until I die.
If I can see those two things are true, a $199 lifetime purchase is a no-brainer (and that probably covers a dozen lifetime members’ operational costs). :D
Re: How Shamir's Secret Sharing Works
#74To be honest, I always wondered why variations of SSS haven't been seen commercial adoption more. For example, instead of storing API Keys in GitHub repos, the keys could be constructed on the fly by approvers signing their shares. I guess the UX of coordinating share-holders is what kills most implementations...
SSS does suffer though for some serious weaknesses, i.e. it trusts the shareholders. A cheating party can submit a fake share during reconstruction, corrupting the recovered secret, and honest parties have no way to detect this something that verifiable secret sharing fixes.
Anyway threshold crypto is a very elegant field and the math is there is really beautiful.
Re: How Shamir's Secret Sharing Works
#75Bruce Schneier described this in his seminal book Applied Cryptography, and HashiCorp Vault used to have an implementation in Go. On the practical side, I always wondered how large - in bits - the shares should be. One answer I got on a news group was "1 bit more than the actual key length". Nowadays, I wonder how the quantum computing threat would inform 1) share size choice and 2) pro/con Secret Sharing in general.…
Do you remember why 1 bit more?
Just spitballing; I have seen prefixing integers of arbitrary length with a bit 1 as the most significant bit as a way to avoid loosing the leading 0s when serializing the integers if the size is important. Also, IIRC, it's possible to implement shamir using arbitrary length integers instead of a common finite field. Not sure why someone would recommend doing either in that context though.
Re: How Shamir's Secret Sharing Works
#76ente means mine in Malayalam language. it's said to be one of the toughest Indian language to learn. FYI.
> it's said to be one of the toughest Indian language to learn. By who? My SO is now passably conversant in Malayalam after watching their cinema during the covid lockdowns (~1y to 2y).
By other indians. And indian military use malayalam to communicate, so that enemies cannot intercept. There was a report that chinese started learning south indian languages. Most movies use neutral phonetics (written language) where as spoken language is tough to understand and have many regional vriations.
Re: How Shamir's Secret Sharing Works
#77This is such a cool technique, and you could even teach it in secondary schools as a neat thing computer scientists can do with polynomials.
I am a secondary math teacher and I do exactly this with my students. When working on retrieving the expression of an affine function, I tell them about Shamir'..., they choose a secret pin as the slope, generate two points, give them to two other students who have to pair together to find the pin again. The students are always very engaged.
I'm so glad it works. If you handwave at the generalisation to quadratics and higher polynomials, do the students follow it well? I assume you don't get into the finite field stuff, but it seems like it'd be cool to handwave at "there's actually other structures where most of this polynomial stuff works, even in somewhat weird ways".
Re: How Shamir's Secret Sharing Works
#78Earlier quoted context omitted.
Indeed, that's precisely why I decided to ditch out of the subscription model and went into one time payment method, did the math and it made sense that I don't need a very heavy system apart from supporting the dead man switch trigger Wrote my thoughts about that here: https://eternalvault.app/blog/why-we-are-adding-lifetime-pri... And it feels good to know that there are people out thinking about this, makes me hap…
That’s great, and exactly what I was thinking. In fact, you have to wrestle with the fact that if it’s too cheap, people won’t trust it. One thing I had been thinking about was that it’s important to be extremely open about the algorithms and infrastructure required, with a very transparent whitepaper on how it works (enthusiast level discussion of the technical details) and how you have designed the company to be ex…
Honestly those are 100% fair questions, for (1), I have a security page: https://eternalvault.app/security/ but mainly because of marketing purposes, most people I have as customers are in their 30-40s and not fairly technical, so when they ask me, I have to be mindful to not bombard them with too much technical info, but it's a good idea to still have a whitepaper with more detailed info for someone who actually wants to confirm on the privacy aspects.
Regarding (2), that is the most common question I get and honestly I don't know if I have the best answer for it, but here's what I have, I have two vaults for myself (of course I use Eternal Vault myself), one for family and one for business, in the business vault I have few documents including one called "Business continuity plan" which lays down all of my raw thoughts around how eternal vault is built, core technical things, infrastructure, dooms day trigger etc, and other business specific documents, right now since I don't have any heir, I have added few close people to it who are also fairly technical to keep it running, but eventually my idea is to expand on it in such a way that if I'm removed from the equation, the product can still sustain itself both business and ops wise, but I can totally understand why someone would trust a stranger on the internet, so I'm actually not sure how can I make the answer for 2nd much better, what do you recommend?
Re: How Shamir's Secret Sharing Works
#79Earlier quoted context omitted.
That’s great, and exactly what I was thinking. In fact, you have to wrestle with the fact that if it’s too cheap, people won’t trust it. One thing I had been thinking about was that it’s important to be extremely open about the algorithms and infrastructure required, with a very transparent whitepaper on how it works (enthusiast level discussion of the technical details) and how you have designed the company to be ex…
Honestly those are 100% fair questions, for (1), I have a security page: https://eternalvault.app/security/ but mainly because of marketing purposes, most people I have as customers are in their 30-40s and not fairly technical, so when they ask me, I have to be mindful to not bombard them with too much technical info, but it's a good idea to still have a whitepaper with more detailed info for someone who actually wan…
Well one idea I had that changes the operational posture somewhat is to have the “reader” UX be a static page served completely from S3 and referencing other static S3 resources (the encrypted blob), then have the dead man’s switch “fail open” if the “user is not dead yet” signal goes offline. That way the company could almost run out of money and cease active operations but still have the data be readable by end users (with the keys, of course) for a long time. Having such a fallback plan in place gives confidence.
The other thing is being very transparent about the real world incremental cost of a user’s data. It slightly undermines the price point, but being able to say “look, incremental storage cost for your data over your lifetime is 33 cents. We have a bond that covers our current user base in perpetuity ten times over” is pretty compelling. You can say “yes, you’re paying way more than the incremental cost, but you’re paying for the care that went into making sure it’s got longevity.”
I can’t stress enough how happy I am for you that you built this thing that I consider a fabulous idea. I have an idea about how you can market it if you want to hear it. Let me know the best way to email you.
Re: How Shamir's Secret Sharing Works
#80something tangentially i am interested in is computing following the 'two person rule' for things like sudo. Yes I am logged into server X at terinal Y, and so is my co-worker and we both sign off on running command X
I wrote something like that about 15 years ago for a financial institution.
For what we needed, we intentionally wanted both people to be at the same terminal (it was going to be used to give shell access to a specific unix account that ran a critical system).
That mean that we could implement it as a setuid (root) binary that required both users to authenticate. It had a config file that worked like sudoers, and defined a list of commands that could be called, how many people were needed to authenticate, and which unix groups they had to belong to.