【摘要】 基于CP-ABE算法,提出一个云存储环境下支持已注册合法用户动态撤销的属性基加密方案。与传统的委托云中心代理重加密思想不同,本方案中密文是由云存储中心产生的部分密钥k和数据拥有者放在访问结构中的s值共同作用产生,满足属性访问结构的用户可以重构s,恰好抵消部分密钥k在密文中的盲化因子而得到数据明文。当已注册合法用户撤销后,云存储中心更新原来用于加密的部分密钥为k′以及部分密文,即可阻止注册用户撤销后无法解密数据,从而保护数据的后向安全性。未注销用户也仅需更新部分解密私钥即可正常解密,方案整体所需计算量、更新存储量和通信量较低。更多还原

【Abstract】 Based on the CP-ABE algorithm,an attribute-based encryption scheme supported dynamical registered user revocation in cloud storage is proposed in this paper.Ciphertext is encrypted by the partial key kfrom the cloud storage center and s from the data owners which be hidden on the access structure,the users whose attributes satisfy the access structure can reconstruct s and decrypt the plain data because the ciphertext can eliminate the blind factor with the partial key k.After the revocation of a registered legal user happened,the cloud storage center update the original symmetric key kto k′as well as the partial ciphertext of data,which can prevent those revoked users decrypting the data and provide the backward security the shared data.The unrevoked users only need to update the partial private key and they can normally decrypt the updated ciphertext.The whole scheme required lower computation,updating storage and communication cost.更多还原