Patent ID: 7797533

Claim:
A communication system in which an image processing apparatus and a client communicate data with each other through a network, wherein said image processing apparatus comprises: a root certificate creator which creates a root certificate including a public key paired with a private key and being signed with the private key; a second certificate creator which creates, when a connection for communication is requested by said client, a second certificate designating the root certificate created by said root certificate creator as a certificate authority at a higher level and being signed with the private key used to sign the root certificate; and a communication device which transmits the second certificate created by said second certificate creator to said client; and wherein said client comprises: a storage device which has stored therein, before the connection for communication is requested to said image processing apparatus, the root certificate created by said root certificate creator; and a verifier which verifies the signature of the second certificate received from said image processing apparatus with the root certificate stored in said storage device.