Abstract: Having advantage in cloud type computing, people can get a real, inexpensive way to information distribution in group users through a font of low preservation and low management cost. Since they will be outsourced to third parties we have to provide some guaranteed security for the files to be shared. Unluckily, because of regular change of connection, providing confidentiality preserving while sharing data is even now a matter of tricky, specifically for the untrusted cloud due to the conspiracy attack. The way of securely distributing key is mainly based on secure message channel especially for accessible methods having these type of control is a very strong belief and to practice it is difficult. Coming to this document we are planning a safe information distribution format to active users. First step, not including any safe message channels a secure mode for key distributing is proposed and by the group manager private keys can be obtained securely by the users. Secondly, a very well grained access control can be achieved by our scheme; the source can be used by several users in group that is stored in cloud. The revoked users could not be accessed by the cloud yet again when they will be revoked. Now, thirdly the scheme can be protected from conspiracy attack that is that the real data file cannot be retrieved by revoked users even still they accessed with untrusted cloud. In this method we can get a safe user revocation method by establishing leveraging polynomial task. Finally, preceding users not required to revise private keys of their even a fresh user joined in a group or he/she be revoked from active group.

Keywords: Anti-Conspiracy Data Model, private keys, active users.