Puncturable-based broadcast encryption with tracking for preventing malicious encryptors in cloud file sharing.

Cloud file sharing (CFS) in cloud storage is one of the essential tools for enterprises to improve their core competitiveness. In the sharing process, user dynamic management and players/readers abuse has always been a problem that needs to be solved, but malicious encryptors are also a new challenge. Therefore, preventing malicious encryption is another way to protect copyright issues. This scheme proposes a traitor tracing scheme with puncturable-based broadcast encryption in cloud storage, which is an improved scheme proposed in Ref. Garg et al. (2010). Based on the original completely collusion resistant traitor tracing scheme, the uniform distribution of hash output is used to prevent malicious encryptors. In addition, users can perform authentication during the decryption phase to prevent replay attacks. At the same time, the puncture algorithm is introduced, so that normal users can dynamically revoke themselves without affecting the normal use of other users. We prove that the scheme is secure under chosen plaintext attack (CPA). Theoretical analysis also shows that our scheme can prevent malicious encryptors in cloud file sharing and allow normal users to dynamically revoke. After experimental verification, our scheme offers distinct advantages over the existing one. • Prevent malicious encryptors. We use the feature of uniform distribution of hash output to hash random numbers, which makes it impossible to embed the random trapdoor. • Dynamic management of users. We incorporate puncture encryption that allow legitimate recipients to update their private key by self-puncture, thereby revoking the private key's ability to decrypt message. Also, the ability of other recipients to decrypt messages is not affected. • User self-verification. During encryption, The user hashes the decrypted M and R , and then compares them with h = H (R ‖ M ‖ L) to see whether they suffer replay attacks. [ABSTRACT FROM AUTHOR]