Abstract: The technique named assured deletion was namely that the expired or backup data was reliably deleted and remain permanently unrecoverable and inaccessible by any party. However, the previous schemes only deleted the key while the cipher text still maintains entirely. Once the key was compromised, it would be a great threat to the privacy of sensitive data. Therefore, it cannot satisfy the real sense of assured deletion. Aiming at the above problems, a new scheme based on cipher text sample slice named ADCSS was proposed. The scheme can ensure that the cloud server only store the incomplete data by means of cipher text sample slice, which contributes to the top confidentiality of outsourced data even the key is obtained by accident or by malicious attacks. Moreover, the goal of assured deletion can be achieved by destroying the exact cipher text. Theoretical analysis and experimental results show that the proposed scheme can meet the requirement of the assured deletion of sensitive data on cloud storage. Moreover, the scheme performs higher security than the existing ones with low performance overhead.

Key words: cloud storage; data privacy; assured deletion; ciphertext sample slice