Key-Aggregate Cryptosystem for Scalable Data Sharing in Cloud Storage
Data sharing is an important functionality in cloud storage. In this paper, the authors show how to securely, efficiently, and flexibly share data with others in cloud storage. They describe new public-key cryptosystems which produce constant-size ciphertexts such that efficient delegation of decryption rights for any set of ciphertexts are possible. The novelty is that one can aggregate any set of secret keys and make them as compact as a single key, but encompassing the power of all the keys being aggregated. In other words, the secret key holder can release a constant-size aggregate key for flexible choices of ciphertext set in cloud storage, but the other encrypted files outside the set remain confidential.