In cloud storage environment

client-side data deduplication can detect duplicated files at local

so as to save storage space and network bandwidth effectively.However

client-side deduplication still faces many security challenges.Firstly

since the file hash value is regarded as the evidence of duplication detection

the attacker is likely to obtain a whole file via a hash of the file.Secondly

to ensure the privacy of data

convergent encryption has been widely used in data deduplication technology

but the data itself is predictable

so that convergent encryption still inevitably suffered from violence dictionary attacks.To solve problems mentioned above

this paper uses blind signature to construct a secure key generation protocol

by introducing a key server to achieve the secondary encryption of keys

which efficiently prevents violence dictionary attacks.Furthermore

we propose a Proof of Ownership method based on block key signature.It can effectively prevent the attacker from obtaining the file through a single hash value and can realize the file-level and block-level deduplication of the encrypted file simultaneously.Meanwhile

the security analysis shows that our scheme can be proved to be secure in the random oracle model and can meet the security properties such as convergence key security

tag consistency and anti-violence dictionary attacks.In addition

compared with the existing schemes

the experimental results show that the computational overhead of our scheme is relatively small in terms of file upload and file deduplication.