Patent ID: 8739308

Claim:
A computer-implemented method for identifying sources of unauthorized copies of content, comprising: under the control of one or more computer systems configured with executable instructions, obtaining a copy of content comprising a plurality of records, each record having a decrypted portion of original content that comprises a plurality of original records where: each of the plurality of records corresponds to an original record; a subset of the original records consists of records that each has multiple copies of a portion of the original content that varies among the multiple copies; and for each record having multiple copies of a corresponding portion of the original content, at least two of the copies are encrypted by different keys at least one of which is part of a key hierarchy used to distribute keys to content processing devices, the key hierarchy comprising a root key and a plurality of subordinate keys; selecting, from the plurality of records, records that each correspond to a respective original record of the subset of the original records; generating a key set by at least matching each selected record to a key used to decrypt a corresponding portion of original content to obtain the corresponding decrypted portion of the original content, the generated key set including a particular key that is a subordinate key of the key hierarchy; matching the generated key set to a set of the content processing devices by at least identifying a set of devices having access to all of the keys in the generated key set, access to the particular key being based at least in part on access to a key between the particular key and the root key on a key path connecting the particular key to the root key; and providing one or more electronic records that collectively identify at least a subset of the set of the content processing devices.