Daniele Friolo

Daniele Friolo

I work on cryptography. My main interests are towards Multi-Party Computation, Zero-Knowledge, and blockchain applications. I am currently Assistant Professor (RTDA) at the Computer Science department at Sapienza University of Rome

Publications

Registered (Inner-Product) Functional Encryption

Published in ASIACRYPT, 2023

Registered encryption (Garg et al, TCC’18) is an emerging paradigm that tackles the key-escrow problem associated with identity-based encryption by replacing the private-key generator with a much weaker entity known as the key curator. The key curator holds no secret information, and is responsible to: (i) update the master public key whenever a new user registers its own public key to the system; (ii) provide helper decryption keys to the users already registered in the system, in order to still enable them to decrypt after new users join the system. For practical purposes, tasks (i) and (ii) need to be efficient, in the sense that the size of the public parameters, of the master public key, and of the helper decryption keys, as well as the running times for key generation and user registration, and the number of updates, must be small.

Recommended citation: Francati, D., Friolo, D., Maitra, M., Malavolta, G., Rahimi, A., & Venturi, D. (2023). Registered (Inner-Product) Functional Encryption. ASIACRYPT 2023 (To appear) https://eprint.iacr.org/2023/395.pdf

Efficient proofs of knowledge for threshold relations

Published in ESORICS 22, 2022

Recently, there has been great interest towards constructing efficient zero-knowledge proofs for prac- tical languages. In this work, we focus on proofs for threshold relations, in which the prover is required to prove knowledge of witnesses for k out of l statements. The main contribution of our work is an efficient and modular transformation that starting from a large class of Σ-protocols and a corresponding threshold relation R_k,l provides an efficient Σ-protocol for Rk,` with improved communication complexity w.r.t. prior results. Moreover, our transformation preserves statistical/perfect honest-verifier zero knowledge.

Recommended citation: Avitabile, G., Botta, V., Friolo, D., & Visconti, I. (2022, September). Efficient proofs of knowledge for threshold relations. In European Symposium on Research in Computer Security (pp. 42-62). Cham: Springer Nature Switzerland. https://eprint.iacr.org/2022/746.pdf

Multi-key and multi-input predicate encryption from learning with errors

Published in EUROCRYPT 22, 2022

We put forward two natural generalizations of predicate encryption (PE), dubbed multi-key and multi-input PE. More in details, our contributions are threefold.

Recommended citation: Francati, D., Friolo, D., Malavolta, G., & Venturi, D. (2023, April). Multi-key and multi-input predicate encryption from learning with errors. In Annual International Conference on the Theory and Applications of Cryptographic Techniques (pp. 573-604). Cham: Springer Nature Switzerland. https://eprint.iacr.org/2022/806.pdf