Description

The trend toward outsourcing data storage to the cloud has increased sharply in recent years, including for highly sensitive data such as medical and financial records. This model offers elasticity, resource sharing, and cost reduction, but it also raises major security concerns. Recent history has shown numerous data breaches affecting cloud infrastructures, often caused either by malicious insiders (employees, administrators) or by exploits targeting the lowest software layers. This situation undermines users’ trust in cloud providers and makes it crucial to guarantee data confidentiality (protection against any unauthorized access), integrity (prevention and detection of unwanted modifications), and auditability (the ability to verify, after the fact, compliance with access policies and the absence of fraud).

Ensuring reliable storage of sensitive data in an uncontrolled distributed cloud environment is a complex challenge. Existing solutions often rely on strong trust assumptions regarding the server, or on a limited adversarial model (honest-but-curious behavior, no active attacks, etc.). In practice, however, these assumptions may no longer hold when the provider itself is compromised. The research question can therefore be stated as follows: how can confidential data be stored and managed on potentially untrusted cloud servers while guaranteeing end-to-end confidentiality, integrity, and auditability? Addressing this question requires rethinking classical approaches by relying on cryptographic techniques and innovative systems mechanisms.

The ultimate goal of this PhD project is to design a new distributed cloud storage architecture combining trusted hardware and advanced cryptography, together with a comprehensive analysis of its security guarantees (formal proofs or arguments) and a solid experimental validation on representative use cases. This dual approach, both theoretical and practical, will make it possible to produce results that are valuable both for the scientific community (new primitives, publications) and for the cloud industry seeking solutions to protect sensitive data.

Skills required

Strong understanding of cloud, storage and secure distributed systems Proficiency in algorithm design and applied cryptography Experience in programming languages such as Python, C++, Rust or Golang Research skills including literature review, data analysis, and academic writing Excellent verbal and written communication skills Ability to work independently and as part of a team Master's degree in Computer Science, Information Technology, or related field Prior research experience in cloud storage, systems or distributed systems is a plus

Bibliography

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[3] Stefan Contiu, Laurent Reveillère, Etienne Rivière (2020). Practical Active Revocation. Middleware 2020.

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[6] Zhou, L., Diro, A., Saini, A., Kaisar, S., & Hiep, P. C. (2024). Leveraging zero knowledge proofs for blockchain-based identity sharing: A survey of advancements, challenges and opportunities. Journal of Information Security and Applications, 80, 103678

[7] Yuncong Hu et al. (2020). Ghostor: Toward a Secure Data-Sharing System from Decentralized Trust. NSDI ’20.

[8] Cappello, F., Caron, E., Dayde, M., Desprez, F., Jégou, Y., Primet, P., ... & Richard, O. (2005, November). Grid'5000: A large scale and highly reconfigurable grid experimental testbed. In The 6th IEEE/ACM International Workshop on Grid Computing, 2005. (pp. 8-pp). IEEE
【9】 Yuncong Hu et al. (2020). Ghostor: Toward a Secure Data-Sharing System from Decentralized Trust. NSDI ’20.
【10】 Wang et al. (2012). Public Auditing for Ensuring Cloud Data Storage Security With Zero Knowledge Privacy. Cryptology ePrint Archive.

Keywords

Storage, Zero Knowledge proog, Distributed systems, Cloud, Secret sharing, Trusted execution environment