A method and system for forming a data table in memory on an end user system. The data table forming a library index of storage locations to electronic digital content in memory. The method consists of retrieving an encrypted file from storage. The file has a beginning, an end and a trailer section located just prior to the end. The file is read from the end a predetermined distance to verify if an identifier is present. Reading and decrypting the trailer section from the file read. Determining if there are any updates in the trailer section. In the case there are no updates in the trailer section then decrypting the reference table containing one or more data table location indicators for data items with the first decrypting key. Next, decrypting one or data items with the first decrypting key. Populating the data table with data items at locations specified in the reference table.