Seminari di Crittografia

Giovedì 27 Luglio a partire dalle ore 9:30 si terranno in aula 127 i seguenti due seminari relativi a tematiche di Crittografia:

relatore: Prof. Nelly Fazio della City University of New York (CUNY), USA
titoloHomomorphic Secret Sharing from Paillier Encryption
A recent breakthrough by Boyle et al.[BGI16] demonstrated secure
function evaluation protocols for branching programs, where the
communication complexity is sublinear in the size of the circuit
(indeed just linear in the size of the inputs, and polynomial in the
security parameter). Their result is based on the Decisional
Diffie-Hellman assumption (DDH), using (variants of) the ElGamal
cryptosystem. In this work, we extend their result to show a
construction based on the circular security of the Paillier encryption
We also offer a few optimizations to the scheme, including an
alternative to the “Las Vegas”-style share conversion protocols of
[BGI16,BGI17] which _directly_ checks the correctness of the
computation. This allows us to reduce the number of required
repetitions to achieve a desired overall error bound by a constant
fraction for typical cases, and for large programs, reduces the total
computation cost.

relatore: Prof. Antonio Nicolosi dello Stevents Institute of Technology, USA
titolo: An LPN-Based Two-Round Secret-Key Authentication Protocol Secure against
Man-in-the-Middle Attacks
We construct a 2-round secret-key authentication protocol secure against
man-in-the-middle attacks assuming hardness of the Learning Parity with
Noise (LPN) problem. This protocol is suitable for low-cost
“Internet-of-Things” (IoT) devices, whose limited circuit size and power
constraints rule out the use of more heavyweight operations such as
modular exponentiation. The protocol is extremely simple, amounting to
a few “noisy” vector product calculations. The security argument
develops via a series of new technical lemmas, which may be useful in
the analysis of similar protocols and may be of independent interest.