Method and system for protecting cable television subscriber-specific information allowing limited subset access

Abstract From the Canadian patent

A television program ratings method and system includes transferring information associated with households from a cable provider to a ratings provider such that the ratings provider has access to information associated with sampled households and lacks access to information associated with non-sampled households. To this end identity information and usage information associated with the households are respectively anonymized and encrypted. Knowledge of the identities of the sampled households enables the anonymized identity information and the encrypted usage information for the sampled households to be respectively de-anonymized and decrypted. The ratings provider knows which households …