1. A method, in a data processing system, for authorizing information flows between devices of the data processing system, the method comprising: receiving a request for authorization of an information flow involving an information object from a first device to a second device; retrieving contents of the information object from the first device; generating a hash key based on the contents of the information object; performing a lookup operation in a hash table based on the hash key to identify a labelset associated with the information object; determining if an entry in the hash table at an index corresponding to the hash key identifies a labelset for the information object; storing a labelset, identifying a sensitivity of the information object, in the entry at the index corresponding to the hash key for the information object if a labelset for the information object is not identified in the entry in the hash table; performing at least one set theory operation on the labelset associated with the information object, a labelset associated with the first device, and a labelset associated with the second device; and authorizing the information flow based on the at least one set theory operation.