Secure storage as a service

Abstract

Cloud storage, as a storage infrastructure, offers many advantages over on-premises storage and even enhances other services, such as streaming services and gaming platforms,

making them more efficient, scalable, and accessible. This aligns with the concept of storage as a service. However, it also raises significant security concerns on data privacy, as most stored data is accessible to the service provider, who could exploit it for profit, and is vulnerable to data breaches. In this dissertation, we systematically study secure storage as a service, including secure cloud storage services and secure cloud storage for other applications.

1. We first studied a secure cloud storage solution for other applications. Many applications provide services for users and rent cloud storage to store user’s data. We modularly designed a secure storage solution for those applications, so that the user’s data is only visible to user-self. Furthermore, the solution is fully compatible with existing cloud storage services such as AWS S3, and transparent to users who can still use the application via one password without concerns of offline attacks.

2. We studied how to enable the version control functionality and corresponding securities

for secure storage. Most cloud storage services offer limited versions and access controls relying on the trust of storage providers. we got rid of the trust on server, designed end-to-end secure Git services. Moreover, the design is compatible with existing Git servers.

3. We studied secure storage with stronger security in terms of key compromise. Key rotation is an effective way to improve key compromise resilience via updating encrypted data under new key periodically, and updatable encryption enables data encryption with key rotation. We first studied updatable encryption with stronger

security that is needed for secure storage. Then we further formalized secure storage system with key compromise resilience.