There are two fundamental expectations from cloud-IoT applications using sensitive and personal data: 1) utility and 2) privacy. Due to the complex nature of cloud-IoT ecosystems, there is a growing concern about data utility at the cost of privacy. While the current state-of-the-art encryption schemes protect users' privacy, they preclude meaningful computations on encrypted data. Thus, the question remains “how can IoT device users benefit from cloud computing without worrying about privacy and security?” Cloud service providers (CSPs) can leverage fully homomorphic encryption (FHE) schemes to build privacy-preserving services. However, there are challenges in adopting them for cloud-IoT devices. Thus, to foster real-world adoption of FHE-based solutions, we propose a framework called proxy reciphering as a service. We leverage schemes, such as distributed servers, secret sharing, FHE, and chameleon hash functions to tailor a solution that enables long-term privacy-preserving computations for encrypted IoT-device data and is secure even after a device-key compromise. We evaluate the framework by developing a testbed and measuring the latencies with real-world ECG records from TELE ECG database. We also analyze the security properties against major cyber threats. We observe that: 1) the computation and communication latencies are acceptable, and the security gains outweigh the latencies introduced; 2) the throughput of the reciphering proxy servers can be increased with preprocessing; and 3) a key-refresh scheme can limit the postcompromise attack exposure window. We infer that proxy reciphering as a service is a practical, secure, scalable and an easy-to-adopt framework for long-term privacy-preserving cloud computations for cloud-IoT applications.

中文翻译：

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加密物联网数据隐私保护计算的有效框架


使用敏感数据和个人数据的云物联网应用程序有两个基本期望：1) 实用性和 2) 隐私。由于云物联网生态系统的复杂性，人们越来越担心以隐私为代价的数据效用。虽然当前最先进的加密方案可以保护用户的隐私，但它们排除了对加密数据进行有意义的计算。因此，问题仍然是“物联网设备用户如何从云计算中受益，而不用担心隐私和安全？”云服务提供商 (CSP) 可以利用完全同态加密 (FHE) 方案来构建隐私保护服务。然而，将它们应用于云物联网设备存在挑战。因此，为了促进基于 FHE 的解决方案在现实世界中的采用，我们提出了一个称为代理加密即服务的框架。我们利用分布式服务器、秘密共享、FHE 和变色龙哈希函数等方案来定制解决方案，该解决方案能够对加密的物联网设备数据进行长期的隐私保护计算，并且即使在设备密钥泄露后也是安全的。我们通过开发测试台并使用 TELE ECG 数据库中的真实心电图记录测量延迟来评估该框架。我们还分析针对主要网络威胁的安全属性。我们观察到：1）计算和通信延迟是可以接受的，并且安全收益超过了引入的延迟； 2）通过预处理可以增加加密代理服务器的吞吐量； 3) 密钥刷新方案可以限制妥协后的攻击暴露窗口。我们推断，代理加密即服务是一种实用、安全、可扩展且易于采用的框架，适用于云物联网应用程序的长期隐私保护云计算。