Addressing mechanisms in mobile IP

An IP client terminal arranged in use to lease an IP address from another IP network node, at least a part of the IP address being derivable from a public key of a public/private key pair belonging to the owning node, the client terminal comprising:

• means for notifying the owning node of a public key of a public/private key pair belonging to the client terminal;
• means for receiving from the owning node, an authorisation certificate including the public key of the client terminal signed with the private key of the owning node;
• wherein the authorisation certificate is subsequently included with messages relating to said IP address and signed with the private key of the client terminal, sent from the client terminal to receiving nodes, and is used by the receiving nodes to verify the client terminal's claim on the IP address.

An IP client terminal arranged in use to authorise a delegated IP network node to use an IP address owned by the client terminal, at least a part of the IP address being derivable from a public key of a public/private key pair belonging to the client terminal, the client terminal comprising:

• means for receiving from said delegated node a public key of a public/private key pair belonging to the delegated node;
• means for generating an authorisation certificate including the public key of the delegated node signed with the private key of the client terminal, and for sending the certificate to the delegated node;
• wherein the authorisation certificate is subsequently included with messages relating to said IP address and signed with the private key of the delegated node, sent from the delegated node to receiving nodes, and is used by the receiving nodes to verify the delegated node's claim on the IP address.

An IP server arranged in use to authorise a client IP node to use an IP address owned by the server, at least a part of the IP address being derivable from a public key of a public/private key pair belonging to the server, the server comprising:

• means for receiving from said client terminal a public key of a public/private key pair belonging to the client terminal;
• means for generating an authorisation certificate including the public key of the client terminal signed with the private key of the server, and for sending the certificate to the client terminal;
• wherein the authorisation certificate is subsequently included with messages relating to said IP address and signed with the private key of the client terminal, sent from the client terminal to receiving nodes, and is used by the receiving nodes to authenticate the messages.

An IP server arranged in use to assume responsibility for an IP address owned by a client terminal, at least a part of the IP address being derivable from a public key of a public/private key pair belonging to the client terminal, the server comprising:

• means for sending to said client terminal a public key of a public/private key pair belonging to the server;
• means for receiving from the client terminal, an authorisation certificate including the public key of the server signed with the private key of the client terminal;
• wherein the authorisation certificate is subsequently included with messages relating to said IP address and signed with the private key of the server, sent from the server to receiving nodes, and is used by the receiving nodes to verify the server's claim on the IP address.