Tree-based reliable multicast system where sessions are established by repair nodes that authenticate receiver nodes presenting participation certificates granted by a central authority

A method of establishing a reliable multicast data distribution session, comprising:

• at a network node acting as a central authority, providing each of a plurality of network nodes with a respective participation certificate serving as a credential enabling the node to participate in the reliable multicast data distribution session, each certificate being digitally signed by the central authority and containing authorization information specifying the manner in which the respective node is authorized to participate in the multicast session, the network nodes including a sender and a plurality of receivers, the receivers being organized into repair groups each including one receiver designated as a repair node for the group, the repair node for each group being responsible for reliably re-transmitting multicast messages received from the sender to any of the other receivers of the group upon request;
• at the repair node for each repair group:
• exchanging participation certificates with the other receivers of the repair group when engaging in dialog with respect to the establishment of the multicast session;
• authenticating the other receivers of the repair group based on their presentation of their respective participation certificates;
• and
• verifying the right of each of the other receivers of the repair group to participate as a receiver in the session based on the authorization information contained in the respective participation certificate;
• and
• at each receiver other than the repair node in each repair group, upon exchanging participation certificates with the repair node of the group when engaging in dialog with respect to the establishment of the multicast session:
• authenticating the repair node of the group based on its presentation of its participation certificate;
• and
• verifying the right of the repair node to participate as a repair node in the session based on the authorization information contained in its participation certificate.

A system for establishing a reliable multicast data distribution session, comprising:

• a central authority;
• and
• a plurality of network nodes, the network nodes including a sender and a plurality of receivers, the receivers being organized into repair groups each including one receiver designated as a repair node for the group, the repair node for each group being responsible for reliably transmitting multicast messages received from the sender to each of the other receivers of the group;
• the central authority being operative to provide each of the network nodes with a respective participation certificate serving as a credential enabling the node to participate in the reliable multicast data distribution session, each certificate being digitally signed by the central authority and containing authorization information specifying the manner in which the respective node is authorized to participate in the multicast session,
• the repair node for each repair group being operative to:
• exchange participation certificates with the other receivers of the repair group when engaging in dialog with respect to the establishment of the multicast session;
• authenticate the other receivers of the repair group based on their presentation of their respective participation certificates;
• and
• verify the right of each of the other receivers of the repair group to participate as a receiver in the session based on the authorization information contained in the respective participation certificate, and
• each receiver other than the repair node of each repair group being operative to:
• (i) exchange participation certificates with the repair node of the group when engaging in dialog with respect to the establishment of the multicast session,
• (ii) verify the right of the repair node to participate as a repair node in the session based on the authorization information contained in the participation certificate received from the repair node, and
• (iii) use the repair node's public key included in the participation certificate to verify and accept digitally signed messages sent by the repair node.

A system for establishing a reliable multicast data distribution session, comprising:

• means, at a network node acting as a central authority, for providing each of a plurality of network nodes with a respective participation certificate serving as a credential enabling the node to participate in the reliable multicast data distribution session, each certificate being digitally signed by the central authority and containing authorization information specifying the manner in which the respective node is authorized to participate in the multicast session the network nodes including a sender and a plurality of receivers, the receivers being organized into repair groups each including one receiver designated as a repair node for the group, the repair node for each group being responsible for reliably re-transmitting multicast messages received from the sender to any of the other receivers of the group upon request;
• means at the repair node for each repair group for:
• exchanging participation certificates with the other receivers of the repair group when engaging in dialog with respect to the establishment of the multicast session;
• authenticating the other receivers of the repair group based on their presentation of their respective participation certificates;
• and
• verifying the right of each of the other receivers of the repair group to participate as a receiver in the session based on the authorization information contained in the respective participation certificate;
• and
• means, at each receiver other than the repair node in each repair group, upon exchanging participation certificates with the repair node of the group when engaging in dialog with respect to the establishment of the multicast session, for (i) verifying the right of the repair node to participate as a repair node in the session based on the authorization information contained in the participation certificate received from the repair node, and (ii) using the repair node's public key included in its participation certificate to verify and accept digitally signed messages sent by the repair node.

A method of establishing a reliable multicast data distribution session, comprising:

• at a network node,
• receiving from a central authority a participation certificate serving as a credential enabling the node to participate in the reliable multicast data distribution session, each certificate being digitally signed by the central authority and containing information specifying that the node is authorized to participate as a repair node in the multicast session;
• exchanging participation certificates with receiver network nodes when engaging in dialog with respect to the establishment of the multicast session;
• authenticating the receiver nodes based on their presentation of their respective participation certificates;
• and
• verifying the right of each receiver node to participate as a receiver node in the session based on the authorization information contained in the participation certificate received from the receiver node.