Patent ID: 8296829

Claim:
A method of searching and retrieving certificates relating to a message received from a sender via a server remote from a computing device, the message comprising a first part and a second part, the first part comprising a header and a message body of the message, and the second part comprising data identifying a sender certificate associated with the message, wherein the method comprises: at the computing device, receiving, from the server remote from the computing device, at least some data of the first part of the message but not of the second part of the message, wherein the at least some data of the first part of the message contains first certificate identification data that uniquely identifies the sender certificate, the first certificate identification data having been added to the at least some data by the server; and determining whether the sender certificate is stored on the computing device, by generating second certificate identification data associated with each of a plurality of certificates stored on the computing device, and comparing the generated second certificate identification data for each of the plurality of stored certificates to the first certificate identification data contained in the at least some data of the first part of the message received from the server, to identify the one stored certificate matching the sender certificate.