The blockchain itself is a technological core, and can be imagined as Internet without web pages and related services, or booking.com without any hotel.
To support the blockchain expansion, a simple application Blockchain Notarius was developed. The Blockchain Notarius naturally exploits properties of the blockchain.
The Blockchain Notarius can calculate a hash from a document, add potential meta-data to a hash (if the user wishes), and save the hash (with potential meta-data) to the blockchain.
A part of the application, publicly accessible from the web, allows to verify the existence of the hash and display the associated meta-data. This application runs on all the nodes of the network. Hence, the existence of a hash can be verified on any server - at IBM, at the Czech Technical University, at the Electrical and Electronic Association of the Czech Republic, at the Confederation of Industry of the Czech Republic, at Rowan Legal, etc. Currently, there are several dozens of such points (the list here).
The example of use no. 1:
The example of use no. 2:
Extended functionality of Blockchain Notarius:
A further useful function was added to the application: a remote signing of documents.
The application can pre-register the document and generate special access data (the operation ID and PIN, similarly to the Internet banking). Access information is sent to the counter-party (by independent channels, preferably). The counter-party can accept the document and save it to the blockchain finally.
An example