| 摘要: |
| 代理重加密是在保证重加密授权者私钥安全的前提下进行密文转换的操作,实现了云中数据的动态共享。而在基于属性的代理重加密方案中,其代理方可以在不泄露明文数据的前提下,将访问策略下的密文经过重加密转换为不同的访问策略下的密文,完成密态数据的安全外包计算。现有的属性代理重加密方案只是实现了密文策略的更新变换,存在着实用性低,计算量大等缺点。为了满足用户权限的动态更新,以及传统属性加密体制中用户离线后不能向他人提供解密能力的问题,本文提出了一种云中可动态更新的属性基代理重加密方案。通过在系统公开参数中加入用户集合信息并利用属性撤销技术,分别实现了用户集合与属性集合的动态更新,以保证用户权限的动态更新,并且该方案满足单向性、非交互性、非传递性、非转移性和可验证性等特点。此外,利用离线加密技术将加密操作分成两步实现,大量的辅助计算在离线阶段进行,降低了用户客户端在线加密的计算开销。同时,受理者可以对代理重加密密文进行验证操作,避免数据遭受第三方破坏。安全性方面,在标准模型和判定性q阶双线性Diffie-Hellman假设下,证明了本方案具有选择明文攻击下的密文不可区分性且可抵抗同谋攻击。最后,通过效率分析发现,本方案的在线加密阶段计算量较小且用户的密钥和密文存储开销低,具有良好的实用性。 |
| 关键词: 代理重加密 属性加密 访问策略 动态更新 离线加密 |
| DOI：10.19363/J.cnki.cn10-1380/tn.2022.05.04 |
| 投稿时间：2021-04-26修订日期：2021-09-01 |
| 基金项目:国家自然科学基金(No.62072369,No.62072371,No.61802303,No.61772418),陕西省重点研发计划(No.2021ZDLGY06-02,No.2020ZDLGY08-04,No.2019KW-053),陕西省创新能力支持计划(No.2020KJXX-052,No.2017KJXX-47),陕西省自然科学基金(No.2019JQ-866,No.2018JZ6001),陕西省教育厅科研项目(No.19JK0803) |
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| Dynamically Updatable Attribute Based Proxy Re-encryption Scheme in Cloud |
| YANG Geng,GUO Rui,ZHUANG Chaoyuan,WANG Xutao |
| School of Cyberspace Security, Xi'an University of Posts and Telecommunications, Xi'an 710121, China;National Engineering Laboratory for Wireless Security, Xi'an University of Posts and Telecommunications, Xi'an 710121, China |
| Abstract: |
| Proxy re-encryption is the operation of ciphertext conversion under the premise of ensuring the security of the re-encryption authorizer's private key, which realizes the dynamic sharing of data in cloud. In the attribute-based proxy re-encryption scheme, the agent can re-encrypt the ciphertext in the access policy into the ciphertext in different access policies without revealing the plaintext data to complete the encrypted data security outsourcing calculations. The existing attribute proxy re-encryption scheme only realizes the update and transformation of the ciphertext policy. That has the shortcomings of low practicability and large amount of calculation. In order to meet the dynamically updatable of user permissions and the problem that users cannot provide decryption capabilities to others after offline in traditional attribute encryption systems, this paper proposes a dynamically updateable attribute-based proxy re-encryption scheme in cloud. By adding user set information into system public parameters and using attribute revocation technology, the dynamic update of user set and attribute set is implemented to ensure the dynamic update of user permissions. The scheme meets the characteristics of one-way, non-interaction, non-transitivity, non-transferability and verifiability. In addition, the offline encryption technology is used to divide the encryption operation into two steps, and a large number of auxiliary calculations are performed in the offline phase, which reduces the computational overhead of online encryption at the user's client. At the same time, acceptor can verify the proxy re-encrypted ciphertext to prevent data from being damaged by a third party. In terms of security, under the standard model and the q-parallel bilinear Diffie-Hellman assumption, it is proved that this scheme has the indistinguishability of ciphertext under the selected plaintext attack and can resist the collusion attack. Finally, through the efficiency analysis, it is found that the online encryption stage of this scheme has a small amount of calculation and the user's key and ciphertext storage overhead is low, which has better practicability. |
| Key words: proxy re-encryption attribute encryption access policy dynamically updatable offline encryption |
