Functional Encryption with Secure Key Leasing
Fuyuki Kitagawa, Ryo Nishimaki

TL;DR
This paper introduces a new cryptographic primitive called secret-key functional encryption with secure key leasing, providing enhanced security features and instantiations under standard cryptographic assumptions, including post-quantum ones.
Contribution
It defines new security notions for SKFE with secure key leasing and achieves transformations and instantiations based on standard and post-quantum assumptions.
Findings
Achieves bounded collusion-resistant SKFE for P/poly with post-quantum assumptions.
Defines and constructs collusion-resistant SDFE from post-quantum obfuscation.
Provides a stronger primitive than existing secure software leasing schemes.
Abstract
Secure software leasing is a quantum cryptographic primitive that enables us to lease software to a user by encoding it into a quantum state. Secure software leasing has a mechanism that verifies whether a returned software is valid or not. The security notion guarantees that once a user returns a software in a valid form, the user no longer uses the software. In this work, we introduce the notion of secret-key functional encryption (SKFE) with secure key leasing, where a decryption key can be securely leased in the sense of secure software leasing. We also instantiate it with standard cryptographic assumptions. More specifically, our contribution is as follows. - We define the syntax and security definitions for SKFE with secure key leasing. - We achieve a transformation from standard SKFE into SKFE with secure key leasing without using additional assumptions. Especially, we…
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Taxonomy
TopicsCryptography and Data Security · Quantum Computing Algorithms and Architecture · Quantum Information and Cryptography
