The invention comprises a method for registration of data in a blockchain database, in which database transactions are constructed of standard data containers which may have a fixed size, in a system comprising one or more storage nodes for storing at least part of the blockchain database, one or more approval nodes for approving transactions in said blockchain database and a first computer for generating transactions in said blockchain database, said computer having access to said blockchain database and having access to a first private key. The invention further comprises a method for verifying data based on the aforementioned method for registration and an application of these methods to handle a selected type of document. The invention also comprises a computer program product comprising program code stored on a computer readable medium, said program code comprising computer instructions for performing these methods.