One of the use cases of blockchains like Bitcoin are "smart property" contracts.
There is a nice introductory article in the
Bitcoin Wiki. In short: Smart property uses digital "tokens" that represent "real things" (goods and services) and give the owner a kind of access right. For example, if the "good" is represented is a phone, that token could contain a "unlock code" that is necessary to use it.
Other ideas could be tokens that contain "legal contracts" regarding an ownership right between a provider of a good or service and the owner of the token, althought that would be a bit more complex because for some jurisdictions the contract would probably have to be changed, so the "access key" idea seems to be way easier to implement.
My interest on that topic has increased in the last month because I thought such "smart property" contracts could be used to "back" Bitcoin in some way in a transparent good-and-service market on the blockchain. But I currently find very few information of the
current usage/state of that concept - there are many old articles and forum threads from 2011 to 2014, some also related to altcoins.
Does someone know if smart property is already
really used now and what are the currently discussed implementations and concepts?
Right now the tech we have, I don't think that blockchain can help anymore than being an intermediate between a transaction whether it is buying or selling of something or allocation of properties or bonds. Blockchain can only help in building a trust between the two parties since their transaction will be visible to all and hence there will be no fraud. What you are saying is something to another level. Some encrypted key to be used to unlock physical properties or things directly using blockchain tech is not possible as for now. But can be a good idea to research upon in Internet of Things.