The development of cloud services in recent years has mushroomed, for example, Google Drive, Amazon AWS, Microsoft Azure. Merchants can easily use cloud services to open their online shops in a few seconds. Users can easily and quickly connect to the cloud in their own portable devices, and access their personal information effortlessly. Because users store large amounts of data on third-party devices, ensuring data confidentiality, availability and integrity become especially important. Therefore, data protection in cloud storage is the key to the survival of the cloud industry. Fortunately, Proxy Re-Encryption schemes enable users to convert their ciphertext into others ciphertext by using a re-encryption key. This method gracefully transforms the users computational cost to the server. In addition, with C-PREs, users can apply their access control right on the encrypted data. Recently, we lowered the key storage cost of C-PREs to constant size and proposed the first Key-Aggregate Proxy Re-Encryption scheme. In this paper, we further prove that our scheme is a CCA-secure Key-Aggregate Proxy Re-Encryption scheme in the adaptive model without using random oracle. Moreover, we also implement and analyze the Key Aggregate PRE application in the real world scenario.

翻译：近年来，云服务的发展如雨后春笋般涌现，例如Google Drive、Amazon AWS、Microsoft Azure。商家可以轻松利用云服务在数秒内开设在线商店。用户能够通过便携设备便捷快速地连接云端，并毫不费力地访问个人信息。由于用户将大量数据存储在第三方设备上，确保数据的机密性、可用性和完整性变得尤为重要。因此，云存储中的数据保护是云产业生存的关键。幸运的是，代理重加密方案允许用户通过使用重加密密钥，将自身的密文转换为其他用户的密文。这种方法巧妙地将用户的计算成本转移至服务器。此外，通过条件代理重加密方案，用户可以对加密数据实施访问控制权限。近期，我们将条件代理重加密方案的密钥存储成本降低至恒定大小，并提出了首个密钥聚合代理重加密方案。本文进一步证明，在不使用随机预言机的自适应模型下，我们的方案是一个CCA安全的密钥聚合代理重加密方案。此外，我们还在实际场景中实现并分析了密钥聚合代理重加密的应用。