An apparatus and method for mapping user-associated data to an identifier. The apparatus includes a processor configured to store a plurality of user identifiers. User identifiers may be determined by way of user or by machine-learning modules or the like. Apparatus receives user-associated data from a user to be stored in a resource data storage system. User-associated data may include a plurality of data sets to be mapped to an identifier. Mapping a data set to an identifier may be user determined or use a machine-learning module. Apparatus is configured to update the immutable sequential listing associated with the data set with the mapped identifier.