Time-Bound Key-Aggregate Encryption For Cloud Storage

Handling huge loads of data that are subject to change within every second, cloud storage services are facing the challenge of properly dealing with the problem of user legality management while making sure that the services are conveniently user-friendly. Ideally, the concept of attribute-based encryption should be applied, meaning that data should be able to be encrypted using some specific attributes before it is uploaded to cloud, so that fine access control is possible. However, in a traditional attribute-based encryption scheme, the user typically needs to have different attribute-based keys for the decryption of various pieces of data downloaded, which really is a lot of trouble. To solve this problem, the idea of key-aggregate cryptosystem has been brought up. With key-aggregate cryptosystem, the user gets to use one single aggregate key to decrypt data that match all the attributes specified by the user. In addition, in some cases of cloud data usage, we as users might not exactly want to share our cloud data with others 24h a day and for as long as it gets. Therefore, in this paper, we shall propose a time-bound key-aggregate encryption scheme for cloud storage, together with the results of some comparisons as well as correctness and security analyses we have made to prove the superiority of our new scheme over related works. Not only will our new scheme take the burden of maintaining the attribute-based keys off the user, but it will also provide satisfactory confidentiality and security for cloud data in a more efficient way. Copyright (c) 2016 John Wiley & Sons, Ltd.