Access to one or more data streams can be controlled by encrypting a description of how segments of the data streams can be assembled, for example, to produce an audio or video program. Access to the one or more data streams can also be provided by obfuscating names of at least some of the segments in order to make it more difficult to determine the proper order for assembling the segments. In at least some embodiments, the data contained in at least some of the segments themselves is not encrypted.