Optimization Of Key Management And Distribution Based On Broadcast Encryption In Cloud

Security issues has been a major hurdle for the adoption of cloud storage. As data encryption is the mainstream method to ensure confidentiality, users always share data by means of key management and distribution. How to achieve key management and distribution securely and efficiently become an important issue of the research of cloud storage.The date sharing scheme employing broadcast encryption allows nobody but the data owner to manage keys without introducing third parties and the data owner doesn't need to be constantly available online. As the key mechanism of the scheme takes insufficient account of dynamics of users and authorities, it doesn't perform good in cloud storage systems. To improve performance of the key mechanism, firstly, we expand the public key by retaining related parameters to make private keys distributed before still available, thus we reduce cost of redistributing private keys. Secondly, we employ lazy revocation to reduce cost of updating keys. Furthermore, we introduce role-based access control to make users grant and revoke access more conveniently.Test result shows the optimized key mechanism takes less time to add users and revoke access than original mechanism. As the key mechanism adapts dynamics of users and authorities, it's suitable for users to ensure confidentiality and integrity of data stored in the cloud.