Constrained Pseudorandom Functions and Their Applications
Authors: D. Boneh and B. Waters
Abstract:
We put forward a new notion of pseudorandom functions (PRFs) we call
Constrained PRFs. In a standard PRF there is a master key k that enables
one to evaluate the function at all points in the domain of the
function. In a constrained PRF it is possible to derive constrained keys
kS from the master key k. A constrained key kS enables the
evaluation of the PRF at a certain subset S of the domain and
nowhere else. We present a formal framework for this concept and show
that constrained PRFs can be used to construct powerful primitives such as
identity-based key exchange and a broadcast encryption system with
optimal ciphertext size. We then construct constrained PRFs for several
natural set systems needed for these applications. We conclude with
several open problems relating to this new concept.
Reference:
In proceedings of Asiacrypt 2013, LNCS 8270, pp. 280-300.
Full paper: pdf