Graded Public Key Infrastructure (GPKI Sample Clauses

Graded Public Key Infrastructure (GPKI. In a public key infrastructure (PKI) setting, parties have a globally consistent view of a keyset, containing n public keys, where n is the total number of parties. As a starting point, we present a construction which is similar to such a PKI. The challenge that we face without an a-priori setup is that we can not easily achieve a globally consistent view on the protocol participants. As discussed in the last Section 2.1, we do not know the exact number of parties, but a known upper bound n. We address this problem by building a so-called graded PKI. A graded PKI differs from a “real” PKI since the local views of parties Pi, Pj on their respective key sets KeySeti, KeySetj can differ. Here we present ΠKeyGrade (c.f. Figure 2), which achieves a graded PKI in the VDF + random oracle model. Our protocol builds on earlier works [KMS14,AD15] which achieve a stronger notion of GPKI with n grades but require O(nκ2) rounds to do so. In contrast, we run a 2-graded proto- col requiring only a constant number of rounds. We begin by giving some intuition about our protocol and identifying the main challenges that it has to overcome. We describe the protocol from the view of a (honest) party P with κ = 1.