Patent ID: 6986046

Claim:
A method of adding an invitee having a public/private key pair to a secure group of collaborators who communicate with messages protected with inter-member keys, the method comprising: (a) selecting at least one of the group members as a chair with authority to add new members to the group and a public/private key pair; (b) sending an invitation message from the chair to the invitee; the invitation message including a signed invitation nonce that is time-varying and includes information identifying the chair, invitation information encrypted with the invitee's public key and signed with the chair's private key; (c) sending an acceptance message from the invitee to the chair, the acceptance message including the signed invitation nonce, a signed acceptance nonce that is time-varying and includes information identifying the invitee, acceptance information encrypted with the chair's public key; (d) sending a new member message from the chair to all members of the secure group of collaborators, the new member message including new inter-member keys; and (e) sending a group data message from the chair to the invitee, the group data message including the signed acceptance nonce and group information protected with the invitee's public key.