Cloud computing platforms are progressively adopting Field Programmable Gate Arrays to deploy specialized hardware accelerators for specific computational tasks. However, the security of FPGA-based bitstream for Intellectual Property, IP cores from unauthorized interception in cloud environments remains a prominent concern. Existing methodologies for protection of such bitstreams possess several limitations, such as requiring a large number of keys, tying bitstreams to specific FPGAs, and relying on trusted third parties. This paper proposes Aggregate Encryption and Individual Decryption, a cryptosystem based on key aggregation to enhance the security of FPGA-based bitstream for IP cores and to address the pitfalls of previous related works. In our proposed scheme, IP providers can encrypt their bitstreams with a single key for a set S of FPGA boards, with which the bitstreams can directly be decrypted on any of the FPGA boards in S. Aggregate encryption of the key is performed in a way which ensures that the key can solely be obtained onboard through individual decryption employing the board's private key, thus facilitating secure key provisioning. The proposed cryptosystem is evaluated mainly on Zynq FPGAs. The outcomes demonstrate that our cryptosystem not only outperforms existing techniques with respect to resource, time and energy significantly but also upholds robust security assurances.

翻译：云计算平台正逐步采用现场可编程门阵列（FPGA）为特定计算任务部署专用硬件加速器。然而，在云环境中，基于FPGA的知识产权（IP）核比特流面临未经授权拦截的安全问题。现有比特流保护方法存在若干局限性，例如需要大量密钥、将比特流绑定到特定FPGA以及依赖可信第三方。本文提出"聚合加密与个体解密"（Aggregate Encryption and Individual Decryption）——一种基于密钥聚合的密码系统，用于增强FPGA IP核比特流的安全性，并解决先前相关工作的不足。在所提方案中，IP提供商可使用单一密钥对一组S中的FPGA板加密比特流，该比特流可在S中任意FPGA板上直接解密。密钥的聚合加密方式确保该密钥仅能通过使用板载私钥进行个体解密来获取，从而实现安全的密钥供应。该密码系统主要在Zynq FPGA上进行了评估。结果表明，本方案不仅在资源、时间和能耗方面显著优于现有技术，同时保持了稳健的安全保障。