Efficient Function-Hiding Functional Encryption: From Inner-Products to Orthogonality

We construct new functional encryption schemes that combine the access control functionality of attributebased encryption with the possibility of performing linear operations on the encrypted data. While such a primitive could be easily realized from fully fledged functional encryption schemes, what makes our result interesting is the fact that our schemes simultaneously achieve all the following properties. They are public-key, efficient and can be proved secure under standard and well established assumptions (such as LWE or pairings). Furthermore, security is guaranteed in the setting where adversaries are allowed to get functional keys that decrypt the challenge ciphertext. Our first results are two functional encryption schemes for the family of functions that allow users to embed policies (expressed by monotone span programs) in the encrypted data, so that one can generate functional keys to compute weighted sums on the latter. Both schemes are pairing-based and quite generic: they combine the ALS functional encryption scheme for inner products from Crypto 2016 with any attribute-based encryption schemes relying on the dual-system encryption methodology. As an additional bonus, they yield simple and elegant multi-input extensions essentially for free, thereby broadening the set of applications for such schemes. Multi-input is a particularly desirable feature in our setting, since it gives a finer access control over the encrypted data, by allowing users to associate different access policies to different parts of the encrypted data. Our second result builds identity-based functional encryption for inner products from lattices. This is achieved by carefully combining existing IBE schemes from lattices with adapted, LWE-based, variants of ALS. We point out to intrinsic technical bottlenecks to obtain richer forms of access control from lattices. From a conceptual point of view, all our results can be seen as further evidence that more expressive forms of functional encryption can be realized under standard assumptions and with little computational overhead.

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“…[TT18,DP19]) and specialized variants (e.g. [BCSW19]). For the case of quadratic functions, current schemes are limited to [BCFG17, ?]…”

Section: Table Of Contents 1 Introductionmentioning

confidence: 99%

Inner-Product Functional Encryption with Fine-Grained Access Control

Abdalla

Catalano

Ursu

2020

Lecture Notes in Computer Science

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“…In [180], Wee presents a family of simple OFE schemes in prime-order bilinear groups under the MDDH assumption. In [27], Barbosa et al extend the Wee's work to the context of function-hiding.…”

Section: Orthogonality Fementioning

confidence: 99%

A survey on functional encryption

Mascia¹,

Sala²,

Villa³

2023

AMC

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<p style='text-indent:20px;'>Functional Encryption (FE) expands traditional public-key encryption in two different ways: it supports fine-grained access control and allows learning a function of the encrypted data. In this paper, we review all FE classes, describing their functionalities and main characteristics. In particular, we mention several schemes for each class, providing their security assumptions and comparing their properties. To our knowledge, this is the first survey that encompasses the entire FE family.</p>

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“…Further works in function-hiding approaches include [13] and [11]. [3] covers an overhaul of efficient techniques. The use of FE for privacy-preserving biometrics has also been subject to intense scrutiny, from [20] for biometric authentication using threshold predicate encryption, to the extreme efficiency of [14].…”

Section: Previous Workmentioning

confidence: 99%

Practical Privacy-Preserving Face Identification Based on Function-Hiding Functional Encryption

Ibarrondo

Chabanne

Önen

2021

Cryptology and Network Security

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Leveraging on function-hiding Functional Encryption (FE) and inner-product-based matching, this work presents a practical privacypreserving face identification system with two key novelties: switching functionalities of encryption and key generation algorithms of FE to optimize matching latency while maintaining its security guarantees, and identifying output leakage to later formalize two new attacks based on it with appropriate countermeasures. We validate our scheme in a realistic face matching scenario, attesting its applicability to pseudo real-time one-use face identification scenarios like passenger identification.

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Efficient Function-Hiding Functional Encryption: From Inner-Products to Orthogonality

Cited by 7 publications

References 21 publications

Inner-Product Functional Encryption with Fine-Grained Access Control

Inner-Product Functional Encryption with Fine-Grained Access Control

A survey on functional encryption

Practical Privacy-Preserving Face Identification Based on Function-Hiding Functional Encryption

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