mprime1

mês passadodiscuss

Very cool!

Here’s something similar-ish but using symmetric encryption (i.e. password):

https://mprimi.github.io/portable-secret/

https://news.ycombinator.com/item?id=34083366

mprime1

há 2 mesesdiscuss

Shared something very similar on HN a few years ago. The entire source code is about a hundred lines, which makes it easier for folks to review and trust: https://news.ycombinator.com/item?id=34083366

https://mprimi.github.io/portable-secret/

mprime1

há 2 mesesdiscuss

There are some restrictions.

I had the foolish idea of installing a Tesla charger at home to charge my Bolt. I’ve been unable to ever use it.

The wall charger works fine with Teslas. My car and adapter charge fine at Tesla superchargers.

But the home Tesla charger refuses to charge my Bolt. (Yes I disabled vehicle restrictions and tried all sorts of combinations of settings for weeks before giving up. Tesla support was useless of course)

Restriction or bug, same difference.

mprime1

ano passadodiscuss

> 5.9k stars, 727 forks, 132 contributors: https://github.com/nats-io/nats.go

That's the NATS Go _client_.

The server project is https://github.com/nats-io/nats-server 17k stars, 1.5k forks, 160 contributors

mprime1

ano passadodiscuss

Mastodon is another one (ActivityPub / Feediverse)

https://nlnet.nl/project/Mastodon/

mprime1

ano passadodiscuss

> never really understood how just adding extra invisible stuff to make the equations work is justified

IANAP but here’s my understanding.

At the end of the month you spent $2000, you’re not sure how so you track down your expenses:

  - rent $500
  - groceries $120
  - gas $80
  - …
  - unknown: $123

That ‘unknown’ is dark matter. It’s a placeholder. It’s there and makes your total but you can’t explain it yet.

mprime1

ano passadodiscuss

My anecdotal evidence confirms this. Friends in my home country are hooked on Telegram meme groups and as a result they’re spreading [Russian propaganda] conspiracy theories at alarming levels.

(Russia is really good at weaponizing memes but I don’t meant to single it out, the US has also been very successfully influencing the same country for decades via Hollywood movies for example)

mprime1

há 2 anosdiscuss

Stay humble

  - There is someone else that is better at X than you are
  - The person not so good at X is probably better than you at Y

mprime1

há 2 anosdiscuss

Same thing as what?

Parent was asking about deduping encrypted data.

Someone said (wrongly) it’s impossible and I shared a popular project that does exactly that.

mprime1

há 2 anosdiscuss

Indeed. Borg for example is e2e but able to dedupe.

My bookmark archive is 10TB but deduped on-disk size is 100GB because most files are the same across backups!

https://www.borgbackup.org/

mprime1

há 2 anosdiscuss

I had a fascinating conversation with someone that has been working on this system for the last 20 or so years.

Water treatment is powered by the geyser and in turn the leftover brown water feeds the geyser.

Pretty neat (for sewage)!

mprime1

há 2 anosdiscuss

Ordering gives you ... ordering. And nothing more.

Process 1 receives: 3:00 [1] "P1 is leader" 3:01 [2] "P2 is leader"

Process 2 receives: 3:00 [1] "P1 is leader" 4:00 [2] "P2 is leader"

This is perfectly valid Atomic Broadcast. Order is maintained.

However from 3:01 to 4:00PM you have 2 leaders (or 2 processes holding the lock).

Don't use ABCast to do locking / leader election for your "user-space" application!

mprime1

há 2 anosdiscuss

Rounding up 'usually works' to 'is reliable' is a recipe for building crappy systems.

Rounding down 'usually works' to 'it's not perfect and we need to handle edge cases' is how you build dependable systems.

Your first comment seemed very much in the first camp to me.

mprime1

há 2 anosdiscuss

The fatal flaw is calling them "locks".

When programmers think of locks, they think of something that can be used to guarantee mutual exclusion.

Distributed locks have edge cases where mutual exclusion is violated.

Implementation does not matter.

e.g. imagine someone shows you a design for a perpetual motion machine. You don't need to know the details to know it doesn't work! It would violate the laws of physics!

Similarly, anyone telling you they created an implementation of a distributed lock that is safe, is claiming their system breaks the laws of information theory.

"Distributed locks" are at best contention-reduction mechanisms. i.e. they can keep multiple processes from piling up and slowing each other down.

[Some] Paxos for example use leader election to streamline the protocol and achieve high throughput. But Paxos safety does NOT depend on it. If there are multiple leaders active (which will inevitably happen), the protocol still guarantees its safety properties.

mprime1

há 2 anosdiscuss

> They both reduce to a paxos style atomic broadcast

Atomic Broadcast guarantees order of delivery. It does not (cannot) guarantee timing of delivery. Which is what people want and expect when using distributed lock / leader election.

mprime1

há 2 anosdiscuss

There's some serious flaws in your reasoning.

TCP guarantees order [as long as the connection is active] but it is far from being 'perfectly reliable'.

Example: sender sends, connection drops, sender has no idea whether the receiver received.

In other words, it works until it doesn't. The fact that sometimes it doesn't means it's not perfect.

TCP is a great tool but it doesn't violate the laws of physics. The 2 generals problems is and will always be impossible.

mprime1

há 2 anosdiscuss

I'm sorry, I didn't mean to be bashful. I am not familiar with S3 and maybe what you describe is a perfectly safe solution for S3 and certain classes of usage.

I could not get past the point where you promulgate the idea that ZK can be used to implement locks.

Traditionally a 'lock' guarantees mutual exclusion between threads or processes.

"Distributed locks" are not locks at all. They look the same from API perspective, but they have much weaker properties. They cannot be used to guarantee mutual exclusion.

I think any mention of distributed locks / leader election should come with a giant warning: THESE LOCKS ARE NOT AS STRONG AS THE ONES YOU ARE USED TO. Skipping this warning is doing a disservice to your readers.

mprime1

há 2 anosdiscuss

Notice I did not mention FLP.

Atomic Broadcast (via Paxos or RAFT) does not depend on partial synchrony assumptions to maintain its safety properties.

Your internet or intranet networks are definitely asynchronous and assuming delays are bound is a recipe for building crappy systems that will inevitably fail on you in hard to debug ways.

mprime1

há 2 anosdiscuss

"Distributed locks" are at best a contention-reduction mechanism. They cannot be used to implement mutual exclusion that is _guaranteed_ to work.

I've seen way too many systems where people assume TCP == perfectly reliable and distributed locks == mutual exclusion. Which of course it's not the case.

mprime1

há 2 anosdiscuss

Telling people "here's a recipe to do locks" should come with a giant flashing sign that say: "this is not an actual lock (as in in-process locks) -- locks in distributed systems are impossible, this cannot be used as a recipe for mutual exclusion"

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