Abstract: A first code is read from a user carried device useable in an access control system. The first code is an encoded form of at least an ID of a user carrying the device and at least one privilege. The privilege defines the user's access to a resource. The first code is compared to a second code, and access is permitted only if the first code compares favorably to the second code. A reader of the access control system computes the second code based on the user ID and the privilege. The first and second codes may be also based on a secret key applicable only to the user.

Abstract: In one embodiment, a method of forming a secure group from a plurality of nodes for communicating with a user A comprises performing a discover protocol, wherein after performing the discover protocol, all nodes belong to at most one small group and wherein all nodes in each small group share a common key. The method further comprises selecting a leader for each small group. The method further comprises, for each of the leaders, generating a respective common key for the user A and that respective leader. The method further comprises generating a key tree having a plurality of levels, wherein the keys for the lowest level of the key tree are the common keys generated for each leader and wherein the keys for each successive layer are generated by combining pairs of keys from lower levels of the key tree.

Abstract: Non-overlapping time slots are allocated to a plurality of nodes in a network by a mobile agent that moves from node to node of the network. At a current node of the network, the mobile agent accesses neighbor information that includes time slot information relative to neighbor nodes of the current node. The neighbor nodes are neighbors of the current node. At the current node of the network, the mobile agent also assigns mutually exclusive time slots for the neighbor nodes.

Abstract: In one embodiment, a network comprises a plurality of nodes that communicate with one another. A first node included in the plurality of nodes generates a plan comprising a plurality of marker states. Each marker state comprises a value for a property associated with the first node. When the first node broadcasts information indicative of a given marker state included in the plan, at least one node other than the first node verifies the value of the property included in the given marker state.

Abstract: A single mobile agent, multiple mobile agents, or a query mobile agent traverse the nodes of a network. As the single mobile agent, multiple mobile agents, or a query mobile agent visits a nodes of a network, the mobile agent performs a function at the node such as depositing data or software at the node or collecting data from the node. The single mobile agent, multiple mobile agents, or a query mobile agent may be arranged so that all nodes of the network are visited.

Abstract: A first code is read from a user carried device useable in an access control system. The first code is an encoded form of at least an ID of a user carrying the device and at least one privilege. The privilege defines the user's access to a resource. The first code is compared to a second code, and access is permitted only if the first code compares favorably to the second code. A reader of the access control system computes the second code based on the user ID and the privilege. The first and second codes may be also based on a secret key applicable only to the user.

Abstract: In one embodiment, a method of forming a secure group from a plurality of nodes for communicating with a user A comprises performing a discover protocol, wherein after performing the discover protocol, all nodes belong to at most one small group and wherein all nodes in each small group share a common key. The method further comprises selecting a leader for each small group. The method further comprises, for each of the leaders, generating a respective common key for the user A and that respective leader. The method further comprises generating a key tree having a plurality of levels, wherein the keys for the lowest level of the key tree are the common keys generated for each leader and wherein the keys for each successive layer are generated by combining pairs of keys from lower levels of the key tree.