Cloud Multimedia Files Assured Deletion Based on Bit Stream Transformation with Chaos Sequence

As more and more data is outsourced to the cloud, data owners lose direct control of their data. When clients delete their data, it is important to prevent illegal users from visiting the deleted or backup data. The mainstream method of this problem is to encrypt the data in advance, and then protect the decryption key without being sent to unauthorized users. However, if we remain the full encrypted data in the cloud, once the decryption key is stolen by attackers, the data is unsafe. Especially, it is important to protect the privacy of cloud pictures, videos and other multimedia files which contain plenty of private information. In this paper, a new scheme named ADBST is presented for cloud multimedia files. In this method, the bit stream of multimedia files will be transformed into a new one by using logistic chaotic mapping before being encrypted in order to make the cloud file be different from the original file. It can even ensure the security of files on the condition of missing the encryption key. Moreover, this scheme does not bring other third parties in order to reduce the risk of data leakage. Compared with other schemes on the same condition, it only brings little time costs in the acceptable range.