Quantum Key Leasing for PKE and FHE with a Classical Lessor

Speaker: Jiahui Liu , University of Texas

Date: Friday, November 17, 2023

Time: 10:30 AM to 12:00 PM Note: all times are in the Eastern Time Zone

Public: Yes

Location: G-882, Hewlett Room

Event Type: Seminar

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Reminders to: seminars@csail.mit.edu, cis-seminars@csail.mit.edu

Reminder Subject: TALK: Quantum Key Leasing for PKE and FHE with a Classical Lessor

In this work, we consider the problem of secure key leasing, also known as revocable cryptography (Agarwal et. al. Eurocrypt' 23, Ananth et. al. TCC' 23), as a strengthened security notion of its predecessor put forward in Ananth et. al. Eurocrypt' 21. This problem aims to leverage unclonable nature of quantum information to allow a lessor to lease a quantum key with reusability for evaluating a classical functionality. Later, the lessor can request the lessee to provably delete the key and then the lessee will be completely deprived of the capability to evaluate.

In this work, we construct a secure key leasing scheme to lease a decryption key of a (classical) public-key, homomorphic encryption scheme from standard lattice assumptions. We achieve strong form of security where:

* The entire protocol uses only classical communication between a classical leaser (client) and a quantum lessee (server).

* Assuming standard assumptions, our security definition ensures that every computationally bounded quantum adversary could not simultaneously provide a valid classical deletion certificate and yet distinguish ciphertexts.

Our security relies on the hardness of learning with errors assumption. Our scheme is the first scheme to be based on a standard assumption and satisfying the two properties above.

Joint work with Orestis Chardouvelis, Vipul Goyal, Aayush Jain

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Created by Megan F Farmer Email at Thursday, November 09, 2023 at 7:56 AM.