This way both parties could verify the transaction was completed as contracted (IE no joyrides).
I'm still in the camp this probably doesn't need blockchain, but that would at least handle the image manipulation problem.
But yes, depending on the application, photos can be manipulated. But that is stating the problem with using photos, not the timestamping app.
Basically, yes, you could, in theory, maybe, sort of, possibly, build a similar system without a public blockchain. But why? I'm sure there are people who can build houses with a few hand tools, but there's a reason we have power tools and heavy machinery — they are more efficient and fit the job better. The same goes for blockchain in this case.
If you can point out where my logic is incoherent, please do, but to me the following: "oh, just set up a distributed git repo or database with checksums and append-only permissions that you control but replicate to other servers not controlled by you so that you can't tamper with the outputs and read from that global state and verify against the other mirrors of the database or repo every time you read from global state" sounds like a stupider alternative to blockchain.
This is what blockchains were made for!!! Distributed consensus!
Also what is the point of mining or and proof of $whatever system? The thing your customers provide is a signed attestation of some fact and you provide a signed attestation of the time that fact was received. Why is there a need to "vote" in way on what is true? This is just a database or honestly a folder of signed messages.
And I say signed, but none of this really need to be cryptographic in any way since they're customers that could just authenticate to you which is as much a proof of their identity as any key.
The way the transporters know they're getting a fair deal is precisely because we are not the source of truth — a database outside of our control is (a blockchain, in this case).
We're not voting on what is true, we're relying on the blockchain as an immutable representation of state. An append-only, distributed database that we do not control.
And please don't downvote my comments out of a misunderstanding. That's juvenile.
This is a trust problem. Either people trust you, or they don't. You've attempted to increase their trust in you by creating a system that would increase somebody's trust if they had your understanding of the underlying technology. Very few people have this, and the overlap between the people with that understanding and your customers and clients is vanishingly small.
Trust really isn't binary.
> would increase somebody's trust if they had your understanding of the underlying technology.
Or if they had a handwaivey "I've heard that blockchain increases the verifiability of things" level of understanding.