Comment by pests | Hacker News Reader

Comment by pests | Hacker News Reader

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Everyone is claiming this could be done with a database but no one knows all the details because the article is literally three sentences long.

The article states this initiative "helps reduce waste, better manage contamination cases and improve transparency"

This is how I envision this system working. I think the fact this is produce and not normal inventory is key.

Produce is produced by farmers, transported by shipping companies, stored in warehouses, and eventually ends up on a shelf after a long chain of custody.

Reducing waste and contamination sounds like a tracking system. So every food item gets an ID and as it moves through the system it gets logged with time, location, and so on. Pretty standard, and yes, totally doable with a database.

But this project also helps to improve transparency. Transparency to who?

The previous actors in our example. The farmer, the shipper, storage, maybe inspectors.

They have no inherit reason to trust each other. The last shipping company will blame the warehouse for the moldy food. The warehouse will blame the farmer. The inspectors said they approved of it but obviously its gone bad.

Maybe the 6 days to track this produce before wasn't really in tracking it, but dealing with the human element of the chain of custody. Two minutes to pull up a verified log of events.

The key here is "verified". The only way a blockchain is more trustworthy than a regular centralized database is if the nodes are distributed across a large number of stakeholders, and there isn't a chance of anyone gaining control of a majority. That itself becomes impossible since they are using a single account owner (Walmart) on a single cloud provider (IBM).

IBM's platform uses Hyperledger, linked somewhere below.

It has copy on its site stating it "allows multiple different parties to securely interact with the same universal source of truth."

I think the fact that IBM is running this, and not Walmart, is actually a plus. The suppliers don't have to worry about Walmart itself making data changes. Of course the details will vary, but I highly doubt the platform allows the account owner to unilaterally make changes to this source of truth. It's totally against the point of the project.

Having one party to run the system wouldn’t need a block chain, just transparency. Make the data public, available to everyone, with daily hashes of the data of the day combined with the hash from the previous day. Sign that hash+date to prove it has been computed by this central party alone. If the hash cannot be recomputed then there is proof the data has been tempered with. All other parties need to do is to download and store these daily hashes in case of a conflict.

But all of that would be vastly simpler with a central trusted third party.

Global supply chains involve a number of superpowers who are at proxy wars with each other and a vast number of countries of which the majority have deep corruption issues. Who do you designate as the trusted 3rd party?

A company that has no skin in the game and which business it is to be a trusted third party. One of the big audit companies would be my first thought. But there are many businesses that play this role (exchanges, clearing houses, etc).

At the end the job is technically quite simple. Maintaining a semi-public database. It's pretty black or white.

How do you account for rogue employees or hacks at the trusted 3rd party?

Equifax was a trusted 3rd party with no skin in the game.

Facebook was too (at least it was trusted by the west, the chinese never trusted it).

The same you prevent fraud in any industry, procedures, checks and controls. But at least that party has no incentive to fraud.

The moment a physical good is transformed into a item in a database (of any kind), trust is involved. So this isn't a trustless situation anyway. At that point the producer could as well create a new row in an ordinary db. You could sign the data to proof origin of the entry.

But who runs this database and is trusted not to change it?

The trust problem is solved with contract law. If you mean the producer has to trust Walmart not to change its entry after the fact, as stated, they could just sign the entry in an ordinary database.

As Walmart is the sole owner of the database anyway, nothing is gained by using a blockchain.

I have to disagree with you.

Walmart is making this change to improve something. They obviously already have a database somewhere with suppliers and shipments and to think they don't is just crazy.

Sure, contract law. But why when there is a technical solution? If there is a dispute that then has to be settled in the courts with your solution that costs more money and time. The 6 days to 2 minutes might end up way longer after amortizing time spent dealing with trails and compliance and ensuring suppliers are doing things right.

> Sure, contract law. But why when there is a technical solution?

I think I don't see any of the multiple trust relations solved in this case.

Walmart still can't trust the producer to itemize the physical product correctly.

The producer still can't trust Walmart to not change the item already in the database (see mining discussion above).

What trust relation do you have in mind, that is solved with this blockchain implementation, and that wouldn't be solved with a ordinary database with signed entries?

If a hash does not match, that does nothing to your bank account of the inventory of your warehouse. You still need to go to court with your broken hash in case of a conflict. Technology can only help making the evidence temper proof not bypass courts.

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