1. A system, comprising: a processor; and a memory coupled with the processor, wherein the memory is configured to provide the processor with instructions which when executed cause the processor to: receive, from a plurality of platforms, a plurality of backup objects, a plurality of native security descriptors that describe access rights to the plurality of backup objects, and a plurality of object metadata, wherein each backup object has a corresponding object metadata; transform each native security descriptor into a platform independent security descriptor; and generate a partitioned structure which includes a plurality of partitions, including by associating each platform independent security descriptor with those object metadata that correspond to the plurality of backup objects for which that platform independent security descriptor describes access rights to, wherein: each partition in the partitioned structure includes: (1) a platform independent security descriptor that describes access rights to a plurality of backup objects, (2) object metadata that correspond to the plurality of backup objects for which the platform independent security descriptor describes access rights to, and (3) ownership information; and the partitioned structure is used to determine which partitions in the partitioned structure a search user is permitted to access, including by: sending a user credential from a backup catalog server to a user authentication server; receiving, in response to sending the user credential, an identifier for the search user from the backup catalog server; comparing the identifier for the search user against the ownership information in order to eliminate, without considering the platform independent security descriptors, any partitions in the partitioned structure which do not have ownership information which includes the identifier for the search user; and comparing the user credential against those platform independent security descriptors from those partitions which remain after the elimination; the partitioned structure is stored on a backup catalog server; and the plurality of backup objects are stored on a backup catalog database.