Computationally Efficient Distributed and Delegated Certification

Certification in public key cryptographic applications concerns the involvement of a CA (Certifying Agent) in approving the validity of users' public keys. Distributed certification pertains to the case where several CAs are involved in issuing certificates. This also includes the case of multi-attribute certification, where different CAs approve different user's attributes. In delegated certification, agents transfer certificate issuing authority in hierarchical chain. Distributed, multi-attribute and delegated certification techniques having a low computational complexity are presented in this paper. It is shown how multiplicity aspects of the various applications are mapped into a multiplied exponents mathematical implementation of the form Pi
_i=1

^m
A
_i

^bi
mod p, which is essentially equivalent to a single exponentiation for a moderate m. A fundamental feature of the presented procedures pertains to implementing distributed/multi-attribute certification by referring to any desired subset of participating CAs.