Patent ID: 7461250

Claim:
A method performed by a trusted party for exchanging a plurality of certificates together certifying a principal's public key for a single substitute certificate, comprising the steps of: receiving a plurality of certificates each comprising a respective public key and signature of a corresponding distinct certificate signer; determining whether the plurality of certificates forms a certification chain that begins with a root certificate and ends with a final certificate, wherein (1) the certificate signer for the root certificate is trusted by the trusted party, and the respective certificate signers for all the certificates except the root certificate are not required to be trusted by the trusted party, and (2) each certificate in the chain, starting with the root certificate, is unexpired and attests for the validity of a subsequent certificate in the chain, and wherein only the final certificate attests to the validity of the principal's public key; and only if the plurality of certificates forms such a certificate chain, then subsequently issuing a single substitute certificate signed by the trusted party and certifying the principal's public key, in exchange for the plurality of certificates.