A method for registering of a digital document as a digital file 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, comprising the following steps: a) providing a first set of data, relating to the contents of the digital file; b) providing a second set of data, relating to the origin of the digital file; c) generating a third set of data by merging the first set of data, the second set of data, optionally a header and optionally a suffix into a data frame, wherein the header may contain information about the structure of the third set of data, about the size of the first set of data, while the size of the suffix is adjusted such that the size of the data frame is a multiple of the size of the standard data container used in said blockchain database; d) dividing the third set of data into an integer number N>1 of parts of equal size, said size corresponding to the size of the standard data container used in said blockchain database, if the length of the third set of data exceeds the size of the standard data container; e) generating - by said first computer or an intermediary computer connected to the first computer and said one or more of the approval nodes - a single blockchain transaction for all the N parts obtained in the step d), signing the transaction by said first private key and sending the transaction and a first public key matching the said first private key to said one or more approval nodes for approval; f) obtaining approval for the transaction from said one or more approval nodes; g) registering the transaction approved in the step f) in a block of the blockchain database with a timestamp of registration by the one or more storage nodes, wherein the second set of data comprises a digital signature of a hash of the digital file and wherein the digital signature of the hash of the digital file comprised in the second set of data is calculated as a function of: the hash of the digital file and a private key corresponding to the origin of the digital file and wherein registering of the digital document as the digital file in the blockchain database is done by a first entity and the digital document is transmitted from the first entity to a second entity. a) providing a first set of data, relating to the contents of the digital file; b) providing a second set of data, relating to the origin of the digital file; c) generating a third set of data by merging the first set of data, the second set of data, optionally a header and optionally a suffix into a data frame, wherein the header may contain information about the structure of the third set of data, about the size of the first set of data, while the size of the suffix is adjusted such that the size of the data frame is a multiple of the size of the standard data container used in said blockchain database; d) dividing the third set of data into an integer number N>1 of parts of equal size, said size corresponding to the size of the standard data container used in said blockchain database, if the length of the third set of data exceeds the size of the standard data container; e) generating - by said first computer or an intermediary computer connected to the first computer and said one or more of the approval nodes - a single blockchain transaction for all the N parts obtained in the step d), signing the transaction by said first private key and sending the transaction and a first public key matching the said first private key to said one or more approval nodes for approval; f) obtaining approval for the transaction from said one or more approval nodes; g) registering the transaction approved in the step f) in a block of the blockchain database with a timestamp of registration by the one or more storage nodes,