Abstract: The encryption secured computer system (10) includes a server (12) that communicates with clients (14-20) across a public network (21) using a novel transaction coded decryption key technology that discourages wrongful redistribution of protected information such as digital musical scores, and allows for tracking of infringing activity. In one implementation, the server (12) distributes access software and partially encrypted musical scores to clients upon request. A client can sample the partially encrypted scores prior to consummating a transaction. When a score is selected, the client enters payment information and is assigned a password that is specific to the client and transaction. The password functions as a decryption key to enable use of the musical score by the client employing the access software. Any subsequent wrongful redistribution of the musical score together with the decryption password can be traced due to client identifying information encoded into the password.

Abstract: Digital musical information for a musical score is stored in records that are established based on types of musical information or notation and are therefore independent of the musical sequence of the score. In this manner, the information for a single musical element such as a note, clef, or accent can be spread over more than one record, or information for more than one element can be included in a single record. This storage format accommodates subsequent revisions or additions to the score or accessing code, facilitates data compression for enhanced transmission rates, facilitates progressive (e.g., page-by-page) transmission and provides enhanced flexibility for implementing encryption techniques.