Key-Aggregate Cryptosystem for Confidential Data Sharing in Public Cloud

Abstract

That is, the secret key holder can generate a constant-size aggregate key for flexible choices of ciphertext set in cloud storage, but the other encrypted files outside the set can be secure. This compact aggregate key can be sent to others or be stored in a smart card with very limited secure storage. We provide security analysis of our schemes in the standard model and describe other application of our proposed schemes. In particular, our schemes give the first public-key patient-controlled encryption for flexible hierarchy, which was yet to be known.