Description
Fully Homomorphic Encryption (FHE) enables computations to be executed directly on encrypted data without decryption, thus it is becoming an auspicious solution to protect the confidentiality of sensitive data without impeding its usability for the purpose of analytics. While many practical systems rely on FHE to achieve strong privacy guarantees, their constructions only consider an honest-but-curious threat model by default, FHE provides no guarantees that the cryptographic material has been honestly generated nor that the computation was executed correctly on the encrypted data. In particular, in multiparty settings with numerous clients providing data and one or several servers performing the computation, this threat-model becomes even less realistic. Only recently, the cryptographic community has started analysing the guarantees of FHE under stronger adversaries and proposed solutions tailored to the malicious threat-model, however these efforts have remained theoretical and not applicable to real-life scenarios.In our work, we aim at reducing this gap by considering covert adversaries that are malicious but rational (i.e., they do not want to be detected when cheating) and we build different systems that protect the FHE pipeline against such entities. We first propose an efficient solution to prove the correctness of homomorphic operations performed by a server without compromising the expressiveness of the FHE scheme. Then, we propose different protocols to secure input verification and correct encryption in settings where the client encrypting its data is not trusted. Our constructions provide baselines to evaluate the impact of the threat model change in FHE pipelines with real-life implementation constraints.
Next sessions
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Hardware-Software Co-Designs for Microarchitectural Security
Speaker : Lesly-Ann Daniel - EURECOM
Microarchitectural optimizations, such as caches and speculative out-of-order execution, are essential for achieving high performance. However, these same mechanisms also open the door to attacks that can undermine software-enforced security policies. The current gold standard for defending against such attacks is the constant-time programming discipline, which prohibits secret-dependent control[…]-
SoSysec
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Hardware/software co-design
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Micro-architectural vulnerabilities
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Should I trust or should I go? A deep dive into the (not so reliable) web PKI trust model
Speaker : Romain Laborde - University of Toulouse
The padlock shown in the URL bar of our favorite web browser indicates that we are connected using a secure HTTPS connection and providing some sense of security. Unfortunately, the reality is slightly more complex. The trust model of the underlying Web PKI is invalid, making TLS a colossus with feet of clay. In this talk, we will dive into the trust model of the web PKI ecosystem to understand[…]-
SoSysec
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Protocols
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Network
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