Programming

Blockchain and/or smart contracts try to solve problems that were already solved in multiple ways by adding a ton of overhead that makes them unable for large scale deployment and long term usage.

Here's what's stupid about the people who say that blockchain will revolutionize the financial sector: why add a blockchain and all the computing power to store transactions when you can take the obviously efficient route and simply store transactions on a SQL database? Before anyone screams the word "decentralization" do you really think banks will cease to exist? NO. The most likely scenario - if people keep pushing this bullshit - will be to have some kind of closed blockchain that banks use to transact money, so it essentially becomes the same thing we've now with added overhead, environmental impact and technical complexity. We have efficient system in place with safeguards, operations can be tracked, reversed etc.

Frankly it would be a better use of everyone's time, money and effort to simply fix the REAL problems in the banking industry, such as the fact that the US still doesn't have a decently working, standardized digital system to transfer money between account holders in different banks. Europe has this with SWIFT/IBAN and people can transfer money between accounts, banks and countries almost instantly by just providing the amount they want to transfer and an IBAN number (nothing else required). Now tell me, how many people in the US have bank account with IBAN numbers? Most likely only millionaires. The majority of people use a combination of poorly structured system of account and routing numbers that often fail and lead to delays. Oh btw Russia has a similar system to IBAN.

There are tons of other weaknesses in the US banking system around the way credit and debit cards work, for instance why would anyone on their right mind assume that a system where you can provide your credit cards number and CVV/CVC code over a phone to make a transfer wouln't be abused to scam people and steal money? Then, after decades of fraud, to "alleviate" the issue they decided to create a bunch of companies that offer virtual credit cards with limits. Now let this how with works in most European countries: banks will, most likely, refuse any attempt at charging a physical credit card unless its made on a physical payment terminal with the card actually physical inserted on the thing an a 4 digit PIN code typed in. If you want to buy shit over the internet simply open your bank's app or website and they'll have a function to create a single use virtual credit card for the transaction. Way more secure isn't it? :) Either way most European countries also other systems to handle those kinds of payments eg. the online stores provides you with a specific code and you then can go into any ATM or your Bank's App, insert the code and make the payment.

As you can see making the banking system efficient and having fast, secure and usable things isn't about blockchain bullshit, its usually more about common sense and creating standards that companies, such as banks, have to comply with.

Blockchains are only useful in cases where non-repudiability (the ability to prevent users from denying that an event happened) is more important than any other factor. And there are preciously few cases where this is the case, the vast majority being related to audit - tracking receipts, votes, certificates, or similar attestations in an environment where no single party can be trusted. Disclaimer, I've worked in the past in projects related to the aforementioned - fortunately all of them related to the field of audit.

buying drugs

oh, and throwing gasoline at an already burning planet

Blockchain? Oh, hah, no no... none of us were ever hyping up a tech we didn't understand as the solution to literally any problem.

Say, have you heard about AI? It's a revolutionary technology that's the solution to any problem!

The only useful use case I've seen is for when you absolutely MUST be able to track historic data and ensure edits don't destroy the original. Blockchain "solves" this by never allowing saved data to be edited.

The only place I've seen it actually being used properly for that was within Brazil's medical vaccine tracking (ptbr article), which is what allowed them to confirm that Bolsonaro falsified his vaccination card. It doesn't offer details on what kind of protocol it uses, but it could just be a "decentralized, distributed" database, for all intents and purposes.

Git

Git is Blockchain and it's pretty much the only use of the tech I actually see make sense. Most other uses add too much expense where we could just used a trusted ledger. I know people are all about zero trust but the cost benefit of Blockchain doesn't pan out for almost anything. It's not hard to develop cheaper ways to trust an actor, such as laws. Which is how we create trust today. When's the last time your westernized bank stole money from you?

Blockchains are "just" distributed databases with a guarantee about transaction ordering (doesn't have to be totally ordered like regular literal chain-of-blocks but eg. some sort of DAG). Then on top of that you have your consensus-forming mechanism like PoW, PoS or PoA (Proof-of-Authority), most of which are designed to work in a network where you don't trust the participants, except for PoA where nodes that eg. have a cert signed by a specific authority can do validation.

I could see PoA networks being useful for eg. banks, real estate related stuff, DNS (like @jet@hackertalks.com mentioned) etc. Anything where you'd be interested in having all parties agree on some order of transactions, and where validation is only done by trusted actors. DNS-like systems could maybe even be done with public validation, but PoW is out of the question because of the W part, and most PoS-like systems (well, PoW and PoS but still) have lots of problems with validators being incentivized to order transactions in a certain way ("Maximal Extractable Value" et al) that can actually be detrimental to the network (or even consensus) and to the users.

I'm not really super sold on the idea of public blockchain networks where anyone (well, anyone with the means, which is not a small barrier) can be a validator, they mostly seem a bit like a solution looking for a problem. I can easily envision blockchains becoming something like Linux in the sense that they could be used "in the background" in many contexts, but so that us plebs rarely actually have to deal with them (the majority of the Internet runs on some flavor of Linux, but most people don't "consciously" use it apart from Android which does its damndes to pretend not to be Linux).

When NFTs were invented, people imagined them being used for things like titles/deeds. Instant transfer and verifiability would be a huge thing. especially in places that have real estate scams due to the slow/corrupt bureaucracy.

Audit logs and Access control paper trails.

Security event logging has to be:

1. Broadly accessible
2. Write-protected
3. offering some proof of completeness.

These three requirements are tricky and often conflicting. Block-chain might be an inefficient way to achieve these, but the glove does fit quite neatly.

Logistical paperwork

• Purchase Orders/Invoices and packing slips
• Waybills/Bills of lading and CMR's

These kinds of documents require multiple stages of matching and approval by untrusted 3rd parties. There are dozens of ecosystems of interacting systems that support processing these documents, but most people still use paper. Paper is more reliable when you need to deliver a container full of diapers from Poland to North Sudan. It's more reliable but incredibly prone to fraud and forgery. Having all of these approvals and transactions tracked on a blockchain and letting different systems interact with the same chain, would make it possible without each ERP having a rest API to each other ERP.

The only use that I've thought of over the years is event logging where you need a very high confidence that no one has tampered with the logs.

git

Its backing store is an (immutable) merkle tree, which is a chain of crypographically signed object (commits, trees and blob), aka a chain of block, aka a blockchain.

A good while back I read a paper, blog post....I read something somewhere a while back that laid out an interesting use case involving vehicular service records for fleet vehicles. And I know exactly about as much about blockchain then, as I do now, but I did spend some time in fleet logistics for a large scale service company with about 20+ field vans and at the time, the notion seemed compelling and interesting on the face of it.

After a very brief google, it seems the topic has been widely written about but nothing in depth compared to the piece I read all those years ago (which felt more like a full on white-paper). Looking around and will edit the comment if I find it so the people in the room who are smarter than I am can weigh in.

Name lookups. Like DNS.

If you have a trusted Oracle on whatever chain you're using, then your smart contracts can start working with real world data. And that opens up lots of possibilities. Of course it puts a lot of faith in oracles. But for instance you could have an inheritance scheme that triggers on the death of a relative. You could do life insurance. You could affect any sort of contract was transaction money or currency.

To your points about central control, I think it's anthema to the idea of a distributed system. If your resistant to malicious actors you have to be resistant to censorship. Because it's only a matter of time until the central authority becomes a malicious actor. At least for some of the population.