[notatrumper]

Why not? The smart card and the lock are IRL. The smart contract knows who is allowed to open the lock. The lock can query the current state of the contract to check if the smart card being used on it is allowed to open the lock.

I have heard several stories by now of renters being defrauded by fake landlords. A smart contract could actually help. Decentralized would mean everybody can check who owns a property, not just the owner of some obscure property database.

[dodobirdlord]

Until someone secures a court order transferring ownership of a property, at which point the ledger no longer reflects reality. It's an awkward problem for any distributed ledger that wants to track something that isn't intrinsically defined by the ledger itself.

[notatrumper]

Sure, but that is the "ownership" problem, I was talking about the smart lock problem. Yeah I was talking about ownership - but having to verify that externally does not take away from the smart lock problem. I think the typical fraud went that way: previous renters pretended to be landlords and collected upfront money from prospective new renters. If for example only the actual landlord can grant access to the smart card (or NFC phone), it would be harder for previous renters to pull off that fraud.

Isn't there a public ledger of property ownership? In any case, there could be.

In my country, merely transferring property rights costs a lot of money. I know a friend paid 20k just for officials to make the entry in their book.

Blockchain could easily replace that.

Or the "property officials" could have a key and people could verify with the smart contract that some transfer has been signed by the right key.