1 research outputs found
Witness Indistinguishability for any Single-Round Argument with Applications to Access Control
Consider an access policy for some resource which only allows access to users
of the system who own a certain set of attributes. Specifically, we consider
the case where such an access structure is defined by some monotone
function , belonging to some class of function
(e.g.\ conjunctions, space bounded computation), where is the number of
possible attributes.
In this work we show that any succinct single-round delegation scheme for the
function class can be converted into a succinct single-round
private access control protocol. That is, a verifier can be convinced
that an approved user (i.e.\ one which holds an approved set of attributes) is
accessing the system, without learning any additional information about the
user or the set of attributes.
As a main tool of independent interest, we show that assuming a
quasi-polynomially secure two-message oblivious transfer scheme with
statistical sender privacy (which can be based on quasi-polynomial hardness of
the DDH, QR, DCR or LWE assumptions), we can convert any single-round
protocol into a witness indistinguishable one, with similar
communication complexity