Summary: Until recently, the existence of collection of trapdoor permutations (TDP) was believed (and claimed) to imply almost all of the major cryptographic primitives, including public-key encryption (PKE), oblivious transfer (OT), and non-interactive zero-knowledge (NIZK). It was recently realized, however, that the commonly accepted general definition of TDP needs to be strengthened slightly in order to make the security proofs of TDP-based OT go through. We present an implementation of oblivious transfer based on collection of dense trapdoor permutations. The latter is a collection of trapdoor permutations, with the property that the permutation domains are polynomially dense in the set of all strings of a particular length. Previous TDP-based implementations of oblivious transfer assumed an enhancement of the hardness assumption (of the collection).
For the entire collection see [Zbl 1048.94003].