[simias]

>If I had to summarise in few words why - I’d say it’s because of cryptography patterns and immutable/verifiable/temper resistant, distributed ledger that has completely different security profile from traditional systems

The temper resistance is not god-given, it's a consequence of the miners racing to mine new blocks. If you want the same type of resistance for a custom blockchain then you need to convince a bunch of people to mine your chain. Why would I mine MangoCoin?

So instead immutability is achieved by making a "side-chain" that eventually links to a big and secure chain like Bitcoin or Ethereum. But then it's basically the equivalent of having a SQL database, computing a checksum every day and uploading it in a custom bitcoin transaction. Effectively you could achieve the same thing by computing the checksum, signing it with your PGP key and uploading it publicly on your website for all to see. This way anybody can make copies and if you attempt to modify an old entry in your DB it'll invalidate the checksum and anybody having a copy will be able to prove it.

So with this scheme your SQL database is immutable, verifiable and temper resistant. Unfortunately if you implement it that way your announcement won't make the rounds on social media and give you a lot of free PR and a boost to your stock, so better brand it "with real bits of revolutionary Blockchain(c)(tm) technology inside" instead.

>ie there’s nothing to hack

The Blockchain runs on computers, computers can be hacked. People can forge a bad transaction saying that some mangoes are organic when they're not. People can say mangoes have been stolen when in fact they've been sold to avoid paying taxes. The blockchain isn't harder to hack than any distributed database. The Blockchain isn't magic.

[mirekrusin]

PoW is never used for private/custom blockchains, I've never seen it, it doesn't make much sense. If you insist on saying it's just like sql, you'd have to say it's "just like" replicated, multi-master sql database, with publicly exposed read only access, forbidden deletes/updates, inserts restricted/enforced by triggers/whatever based on asymmetric cryptography of currently connected user.

It's just not the same thing, completely different security profile.

The only way to forge transaction is to steal private key.

Nobody is saying that blockchain will force humans to not click "organic" checkbox for non-organic mangoes, this is absurd - but it can encode digital signature of somebody who checks it so it can be later traced back and allows to write logic that signature is required for the mango to go to the next step in the supply chain for example.

I think you don't realize (most people don't) how many problems this little thing solves.

It's not replacement for sql, big data or what not - it would be silly to say that - when designing blockchain systems you actually spend a lot of time on finding the most minimal thing that has to be stored on the chain for your contracts to enforce all required logic. It allows you to trust data in it without security ceremony/setup.