IACR paper details
Title  On Signatures of Knowledge 

Booktitle  IACR Eprint archive 

Pages  

Year  2006 

URL  http://eprint.iacr.org/2006/184 

Author  Melissa Chase 

Author  Anna Lysyanskaya 

Abstract 
In a traditional signature scheme, a signature $\sigma$ on a message $m$ is issued under a public key $\pk$, and can be interpreted as follows: "The owner of the public key $\pk$ and its corresponding secret key has signed message $m$." In this paper we consider schemes that allow one to issue signatures on behalf of any NP statement, that can be interpreted as follows: "A person in possession of a witness $w$ to the statement that $x \in L$ has signed message $m$." We refer to such schemes as \emph{signatures of knowledge}.
We formally define the notion of a signature of knowledge. We begin by extending the traditional definition of digital signature schemes, captured by Canetti's ideal signing functionality, to the case of signatures of knowledge. We then give an alternative definition in terms of games that also seems to capture the necessary properties one
may expect from a signature of knowledge. We then gain additional
confidence in our two definitions by proving them equivalent.
We construct signatures of knowledge under standard complexity assumptions in the commonrandomstring model.
We then extend our definition to allow signatures of knowledge to be \emph{nested} i.e., a signature of knowledge (or another accepting
input to a UCrealizable ideal functionality) can itself serve as a
witness for another signature of knowledge. Thus, as a corollary, we obtain the first \emph{delegatable} anonymous credential system, i.e., a system in which one can use one's anonymous credentials as a secret key for issuing anonymous credentials to others.


Search for the paper
@misc{eprint200621677,
title={On Signatures of Knowledge},
booktitle={IACR Eprint archive},
keywords={signature schemes, NIZK, proof of knowledge, UC, anonymous},
url={http://eprint.iacr.org/2006/184},
note={this is the full version of a paper which will appear in CRYPTO 06 mchase@cs.brown.edu 13368 received 1 Jun 2006, last revised 8 Aug 2006},
author={Melissa Chase and Anna Lysyanskaya},
year=2006
}
Download a complete BibTeX file.