Therefore, one of the important issues of the CSP is how to efficiently manage the ever-increasing data.
An attacker can perform the encryption operation for all possible plaintexts at the offline stage to find the corresponding plaintext information. proposed a technique called Dup LESS that generates a convergent key through the interaction with a key server . proposed a technique for generating a convergent key with the help of other users without a key server . also proposed a method by modifying a single key server in Dup LESS as a group of key servers . first proposed a deduplication scheme that applies the privilege information.
In this scheme, the privilege information is applied when calculating an authentication tag of the file for deduplication.
Therefore, deduplication cannot be achieved in this case. proposed a convergent encryption using a hash value of a plaintext as an encryption key .
Here, the encryption scheme is not large enough (messages are often predictable) .
There are two kinds of ABE schemes: Ciphertext-Policy ABE (CP-ABE) and Key-Policy ABE (KP-ABE) .
In KP-ABE schemes, the ciphertext is associated with a set of attributes while the user’s private key is generated based on his corresponding access policy, while in CP-ABE schemes, a user’s private key is associated with a set of attributes, and ciphertext is encrypted under a specified access structure .
Therefore, many studies on client-side deduplication have been made.
Despite the many advantages of deduplication technique, deduplication technique for the important data has caused several new security problems.
If the deduplication technique does not check file privileges, it would violate file access rights, which would bring some security problems.
Since deduplication inevitably implies data sharing, control over access permissions in encrypted deduplication storage is more important than a traditional encrypted storage.