Paper 2023/1191
Attribute-Based Multi-Input FE (and more) for Attribute-Weighted Sums
Abstract
Recently, Abdalla, Gong and Wee (Crypto 2020) provided the first functional encryption scheme for attribute-weighted sums (AWS), where encryption takes as input $N$ (unbounded) attribute-value pairs $\{\vec{x}_i, \vec{z}_i\}_{I \in [N]}$ where $\vec{x}_i$ is public and $\vec{z}_i$ is private, the secret key is associated with an arithmetic branching programs $f$, and decryption returns the weighted sum ${\sum}_{{i \in [N]}} f(\vec{x}_i)^\top \vec{z}_i$, leaking no additional information about the $\vec{z}_i$'s. We extend FE for AWS to the significantly more challenging multi-party setting and provide the first construction for {\it attribute-based} multi-input FE (MIFE) supporting AWS. For $i \in [n]$, encryptor $i$ can choose an attribute $\vec{y}_i$ together with AWS input $\{\vec{x}_{i,j}, \vec{z}_{i,j}\}$ where $j \in [N_i]$ and $N_i$ is unbounded, the key generator can choose an access control policy $g_i$ along with its AWS function $h_i$ for each $i \in [n]$, and the decryptor can compute $$\sum_{i \in [n]}\sum_{j \in [N_{i}]}h_{i}(\vec{x}_{i,j})^{\top}\vec{z}_{i,j} \text{ iff } g_{i}(\vec{y}_{i}) =0 \text{ for all } i \in [n]$$ Previously, the only known attribute based MIFE was for the inner product functionality (Abdalla et al.~Asiacrypt 2020), where additionally, $\vec{y}_i$ had to be fixed during setup and must remain the same for all ciphertexts in a given slot. Our attribute based MIFE implies the notion of multi-input {\it attribute based encryption} (\miabe) recently studied by Agrawal, Yadav and Yamada (Crypto 2022) and Francati, Friolo, Malavolta and Venturi (Eurocrypt 2023), for a conjunction of predicates represented as arithmetic branching programs (ABP). Along the way, we also provide the first constructions of multi-client FE (MCFE) and dynamic decentralized FE (DDFE) for the AWS functionality. Previously, the best known MCFE and DDFE schemes were for inner products (Chotard et al.~ePrint 2018, Abdalla, Benhamouda and Gay, Asiacrypt 2019, and Chotard et al.~Crypto 2020). Our constructions are based on pairings and proven selectively secure under the matrix DDH assumption.
Note: fixed an editorial error
Metadata
- Available format(s)
- Category
- Public-key cryptography
- Publication info
- A major revision of an IACR publication in CRYPTO 2023
- Keywords
- functional encryptionmulti-input functional encryption
- Contact author(s)
-
shweta a @ cse iitm ac in
tomida junichi @ gmail com
anshu yadav06 @ gmail com - History
- 2023-08-08: revised
- 2023-08-04: received
- See all versions
- Short URL
- https://ia.cr/2023/1191
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2023/1191, author = {Shweta Agrawal and Junichi Tomida and Anshu Yadav}, title = {Attribute-Based Multi-Input {FE} (and more) for Attribute-Weighted Sums}, howpublished = {Cryptology {ePrint} Archive, Paper 2023/1191}, year = {2023}, url = {https://eprint.iacr.org/2023/1191} }