A computer-implemented method for managing digital evidence using a blockchain, the method comprising: receiving an evidence data file, the evidence data file being identified by: an evidence identifier, and a hash code computed from the evidence data file; performing a transformation operation on the evidence data file to produce a transformed evidence data file, wherein the transformation operation comprises: determining if the evidence data file is a PDF file and, if the evidence data file is not a PDF file, perform a transformation operation to convert the evidence data file into a PDF file; collating the evidence data file with at least one further evidence data file to create a composite PDF file; and paginating the composite PDF file by inserting page numbers onto the pages of the composite PDF file, wherein the composite PDF file is the transformed evidence data file; generating a block for the blockchain by combining data indicative of: a hash of a previous block in the blockchain, the evidence identifier, a hash code computed from the transformed evidence data file, the transformation operation, and a timestamp indicating the time at which the transformation operation was performed; and storing the generated block as a new block in the blockchain, wherein the method further comprises: outputting an authenticity indicator simultaneously with an image of a requested transformed evidence data file in response to a user request to enable a user to verify the authenticity of the transformed evidence data file using the data in the blockchain. receiving an evidence data file, the evidence data file being identified by: an evidence identifier, and a hash code computed from the evidence data file; an evidence identifier, and a hash code computed from the evidence data file; performing a transformation operation on the evidence data file to produce a transformed evidence data file, wherein the transformation operation comprises: determining if the evidence data file is a PDF file and, if the evidence data file is not a PDF file, perform a transformation operation to convert the evidence data file into a PDF file; collating the evidence data file with at least one further evidence data file to create a composite PDF file; and paginating the composite PDF file by inserting page numbers onto the pages of the composite PDF file, wherein the composite PDF file is the transformed evidence data file; determining if the evidence data file is a PDF file and, if the evidence data file is not a PDF file, perform a transformation operation to convert the evidence data file into a PDF file; collating the evidence data file with at least one further evidence data file to create a composite PDF file; and paginating the composite PDF file by inserting page numbers onto the pages of the composite PDF file, wherein the composite PDF file is the transformed evidence data file; generating a block for the blockchain by combining data indicative of: a hash of a previous block in the blockchain, the evidence identifier, a hash code computed from the transformed evidence data file, the transformation operation, and a timestamp indicating the time at which the transformation operation was performed; and storing the generated block as a new block in the blockchain, wherein the method further comprises: a hash of a previous block in the blockchain, the evidence identifier, a hash code computed from the transformed evidence data file, the transformation operation, and a timestamp indicating the time at which the transformation operation was performed; and storing the generated block as a new block in the blockchain, wherein the method further comprises: outputting an authenticity indicator simultaneously with an image of a requested transformed evidence data file in response to a user request to enable a user to verify the authenticity of the transformed evidence data file using the data in the blockchain. <EOS>