Functional Encryption for Attribute-Weighted Sums from k-Lin

Michel Abdalla (1) , Junqing Gong (2) , Hoeteck Wee (1)

1 CASCADE - Construction and Analysis of Systems for Confidentiality and Authenticity of Data and Entities
2 ECNU - East China Normal University [Shangaï]

We present functional encryption schemes for attribute-weighted sums, where encryption takes as input N attribute-value pairs (x i , z i) where x i is public and z i is private; secret keys are associated with arithmetic branching programs f , and decryption returns the weighted sum N i =1 f (x i)z i while leaking no additional information about the z i 's. Our main construction achieves (1) compact public parameters and key sizes that are independent of N and the secret key can decrypt a ciphertext for any a-priori unbounded N ; (2) short ciphertexts that grow with N and the size of z i but not x i ; (3) simulation-based security against unbounded collusions; (4) relies on the standard k-linear assumption in prime-order bilinear groups.

Domaines: Cryptographie et sécurité [cs.CR]

Michel Abdalla, Junqing Gong, Hoeteck Wee. Functional Encryption for Attribute-Weighted Sums from k-Lin. CRYPTO 2020 - 40th Annual International Cryptology Conference, Aug 2020, Santa Barbara / Virtual, United States. pp.685-716, ⟨10.1007/978-3-030-56784-2_23⟩. ⟨hal-02948674⟩