An attribute-based framework for privacy preserving image querying

We are specifically concerned with scenarios in which multimedia data is stored once on the server and the same data is queried by multiple parties. We propose a framework for privacy preserving querying, in which encryption is performed only once, and the ciphertexts are stored on a database server. Rather than using public-key homomorphic cryptosystems, the parties querying the database first derive an “attribute” from their query signal. They can decrypt the server´s ciphertext only if their attribute satisfies a specified mathematical condition. This query-specific decryption capability makes attribute-based cryptography a vital addition to the secure signal processor´s toolkit. We give an example of a construction for privacy preserving querying, in which a client can privately retrieve an image from the server if attribute vectors extracted from the server´s and client´s images are close enough in Euclidean distance.