Patent ID: 7017181

Claim:
A method for using identity-based encryption (IBE) to securely convey messages in a system in which senders communicate with recipients over a communications network, wherein the recipients each have an associated IBE public key and an associated IBE private key for use in IBE encryption and decryption, wherein the system includes a plurality of IBE private key generators each of which generates a plurality of associated IBE private keys for a plurality of associated recipients to use in decrypting messages encrypted with their respective IBE public keys, wherein each IBE private key generator generates different IBE public parameter information to be used in encrypting messages for its associated recipients, wherein the different IBE public parameter information generated by each IBE public key generator is maintained by a different respective IBE public parameter host, and wherein each IBE public parameter host has a different service name that is used to communicate with that host over the network, the method comprising: at a sender who desires to send an encrypted message to a given recipient who is associated with a given one of the plurality of IBE public parameter information hosts, using a service name generation rule to determine which of the IBE public parameter hosts should be contacted to obtain the IBE public parameter information that is associated with the given recipient and that is to be used in encrypting the message to the given recipient, wherein using the service name generation rule comprises using the service name generation rule to generate the service name of the IBE public parameter information host that is associated with the given recipient based on the IBE public key of the recipient; using the service name to obtain the IBE public parameter information associated with the given recipient for the sender from the IBE public parameter host that is associated with the given recipient over the network; and at the sender, using the IBE public parameter information obtained from the IBE public parameter host and the IBE public key of the recipient to encrypt a message for the recipient.