UCE+LTDFs: Efficient, Subversion-Resistant PKE in the Standard Model.
Mihir Bellare, Viet Tung Hoang · 2014
This paper provides the first efficient, standard-model, fully-secure schemes for some related and challenging forms of public-key encryption (PKE), namely deterministic and hedged PKE. These forms of PKE defend against subversion of random number generators, an end given new urgency by recent revelations on the nature and extent of such subversion. We resolve the (recognized) technical chal-lenges in reaching these goals via a new paradigm that combines UCEs (universal computational extractors) with LTDFs (lossy trapdoor functions). Crucially, we rely only on a weak form of UCE, namely security for statistically (rather than computationally) unpredictable sources. We then de-fine and achieve unique-ciphertext PKE as a way to defend against implementation subversion via