6.06.14: Prywatne Pozyskiwanie Informacji

Omówiliśmy protokoły Prywatnego Pozyskiwania Informacji (ang. Private Information Retrieval, PIR). Wykład i ćwiczenia odbyły się na podstawie Rozdziałów 2, 3.1, 3.2 i 5.1 pracy:

Benny Chor, Oded Goldreich, Eyal Kushilevitz, and Madhu Sudan
Private Information Retrieval[link]

oraz całości pracy:

Eyal Kushilevitz and Rafail Ostrovsky
Replication Is Not Needed: Single Database, Computationally-Private Information Retrieval[link]

30.05.14: Kryptografia oparta na przekształceniach wieloliniowych

Wykład poświęciliśmy przekształceniom wieloliniowym (ang. multilinear forms) i ich zastosowaniom w kryptografii. Początek wykład prowadzony był według Rozdziałów 1-4 i 6 pracy:

D. Boneh and A. Silverberg
Applications of Multilinear Forms to Cryptography
[link] 

 Potem omówiliśmy (bez pokazywania dowodów) Rozdziały 1-5 pracy:

Sanjam Garg, Craig Gentry, Amit Sahai, and Brent Waters
Witness Encryption and its Applications 
[link]

Na ćwiczeniach pokazaliśmy schemat szyfrowania rozgłaszanego (ang. broadcast encryption) na podstawie Rozdziałów 2 i 3 pracy:

Dalit Naor and Moni Naor, and Jeff Lotspiech
Revocation and Tracing Schemes for Stateless Receivers
[link]

23.05.14: Public-Key Deniable Encryption (gościnny wykład Vincenzo Iovino)

We introduced the concept of public-key deniable encryption explaining for which settings is achievable and for which is not (not achievable in general). We discussed that a public key encryption scheme with perfect correctness cannot deniable so it has to have non-perfect correctness.

Then we presented simple construction of schemes with non-negligible distinguishing advantage (rather than negligible as usual). In particular we presented simple schemes for sender deniability with 1/poly advantage given in Section 3 in this paper (the schemes based on translucent sets and constructions of translucent sets).

Then we said that even though full deniability is in general impossible the researchers found a new clever model called multi-distributional deniability and we started to present this paper. We discussed the philosophical implication of multi-distributional deniability. Then I presented their construction based on simulatable PKE.

We skipped the construction based on bitranslucent sets and we concluded saying that the construction extends easily to the IBE setting. We did not give full proofs for the security but only intuition.