Broadcast Searchable Keyword Encryption

Broadcast Searchable Keywords Encryption (BSKE) is a novel scheme that allows searching in encrypted data without knowing a secret key. Consider Bob wants to encrypt the same data under master public key for a group of users and stores this encrypted data with Alice, Malice is one of those recipients he asks Alice using his private key whether or not she has stored encrypted data, then Alice will search in all encrypted data using the master public key, either she finds a matching then returns encrypted data to Malice or does nothing. We hopefully wish Alice will not learn anything from both encrypted data and the query. Our scheme contributes by providing fixed cipher text O(3) which does not grow with the number of recipients, efficient revocable for users without resets security parameters and the computational cost in the cloud side only. BSKE is designed based on random oracle model and the scheme is secured against adaptive chosen keyword attack.