Homomorphic Encryption Enabled Delta Encoding
David Hasselquist, János Dani, Niklas Ferdinand Carlsson · 2024
The rapid expansion of cloud computing has transformed data storage and processing by providing unprecedented convenience and scalability. However, this progress is shadowed by significant data security challenges, primarily as users must rely on cloud service providers to enforce robust security protocols. Homomorphic encryption (HE) offers a potential solution by allowing computations on encrypted data, thereby maintaining confidentiality without compromising functionality. However, HE can be computationally intensive, raising concerns about its practicality in real-world applications, particularly when dealing with large files. Moreover, constantly re-encrypting an entire file after every modification is inefficient and introduces substantial performance overheads. While traditional delta encoding can be used to optimize bandwidth by transmitting only file modifications, it faces security and privacy concerns as the server must access unencrypted file contents. In this paper, we address these challenges by introducing a novel delta encoding scheme tailored for seamless compatibility with HE, enhancing data confidentiality while maintaining efficiency. Our approach minimizes the overhead of re-encryption and improves performance by encrypting and transmitting only the modified file parts. We evaluate the performance of our scheme across various parameters and test cases, comparing it to a state-of-the-art delta encoding approach. Our findings demonstrate many similarities while highlighting the tradeoffs of our HE-enabling solution. Additionally, we explore the performance impacts of integrating HE with our delta encoding scheme and provide insights into the practical constraints and requirements for real-world deployment in cloud computing environments.