Abstract: A hybrid communications link includes a slow, reliable communications link and a fast unreliable communications link. Communication via the hybrid communications link selectively uses both the slow, reliable communications link and the fast, unreliable communications link.

Abstract: Method and apparatus for varying the times and channels of broadcast beacons. The method and apparatus make it more difficult to monitor and/or disrupt such beacon transmissions. In one embodiment, pseudo-random times and pseudo-random channels are selected for transmitting the beacon messages. Preferably these times and channels are included in a beacon schedule which is transmitted with the beacon messages. In select embodiments, the beacon messages include schedules for both the transmitting node and other nodes, so that all of the nodes in the network may quickly learn the beacon schedules of the other nodes.

Abstract: A method, a node and an energy-conserving ad hoc network are provided that facilitate nodes joining the energy-conserving ad hoc network. A node includes a transceiver (210), a transmitter (206), and processing logic (202). The processing logic (202) is configured to control operation of the transceiver (210) and the transmitter (206). The processing logic (202) is further configured to transmit a wake-up signal via the transmitter (206) and receive a network entry message (600) from one of a group of existing nodes (101) in the network (100). The network entry message (600) includes scheduled times (620, 640) in which at least one of the existing nodes (101) in the network is available to receive. The processing logic (202) is further configured to join the network (100) based on the received scheduled times (620, 640).

Abstract: A system for optical channel access in a network (105) includes multiple distributed nodes (205) that further include a first node (420), a second node (410) and a third node (415). The first node (420) of the multiple distributed nodes requests optical channel access with at least one other node via radio-frequency (RF) messaging. A second node (410) of the multiple distributed nodes grants or denies the requested optical channel access. The third node (415) establishes optical channel access to the first node (420) based on whether the second node (410) grants or denies the requested optical channel access.

Abstract: Systems and a methods are provided for reserving a rate at which cryptographic material is provided. A reservation request [700] for reserving the rate is sent from a secret bits consuming application [410] to a secret bit producing application [405]. The secret bits producing application [405] determines whether the reservation request can be satisfied. When the secret bits producing application determines that the reservation can be satisfied, the rate is reserved for the secret bits consuming application [410].

Abstract: A system transports a key between a first node (505) at one end of a path (500) through a quantum cryptographic key distribution (QKD) network to a second node (525) at an opposite end of the path (500), where the QKD network includes multiple nodes. The system transmits secret bits between the multiple nodes of the QKD network using quantum cryptographic mechanisms. The system reserves (530), from the first node (505), portions of the transmitted secret bits at each intermediate node along the path between the first (505) and the second node (525). The system transports a key between the second node (525) and the first node (505) using the reserved portions (555, 560, 565, 575) of the transmitted secret bits.

Abstract: The present invention performs “flow control” based on the remaining encryption capacity of an encrypted outbound network interface link of a network routing device, such as a router or switch. As the encrypted link begins to run low on encryption key material, this invention begins to discard datagrams queued for transit across that link, in order to signal distant host computers that they should slow down the rate at which they are sending datagrams. The invention, which is particularly useful in cryptographically protected networks that run the TCP/IP protocol stack, allows fine-grained flow control of individual traffic classes because it can determine, for example, how various classes of data traffic (e.g., voice, video, TCP) should be ordered and transmitted through a network. Thus, the invention can be used to implement sophisticated flow control rules so as to give preferential treatment to certain people, departments or computers.

Abstract: A system (125) performs network management in a quantum cryptographic network (115). The system (125) monitors parameters associated with multiple links and multiple nodes of the quantum cryptographic network (115). The system (125) manages the multiple links and multiple nodes of the quantum cryptographic network (115) based on the monitored parameters.

Abstract: Methods and systems are provided for distributing key information by securely transmitting light information in a network along a path comprised of a plurality of network devices and by using a key distribution center (KDC) connected with the network. Three or more user devices connected with the network are specified as constituting a secure communication group. Each user device sets up an end-to-end path to the KDC by configuring at least one of the network devices to direct light information along the path. Thereafter, a user key is established between each user device and the KDC, by sending light information using randomly selected quantum bases through the path. The KDC determines a shared secret key, and notifies each user device of the shared secret key by sending the result of a calculation based on the shared secret key and each user key through the network.

Abstract: The present invention performs “flow control” based on the remaining encryption capacity of an encrypted outbound network interface link of a network routing device, such as a router or switch. As the encrypted link begins to run low on encryption key material, this invention begins to discard datagrams queued for transit across that link, in order to signal distant host computers that they should slow down the rate at which they are sending datagrams. The invention, which is particularly useful in cryptographically protected networks that run the TCP/IP protocol stack, allows fine-grained flow control of individual traffic classes because it can determine, for example, how various classes of data traffic (e.g., voice, video, TCP) should be ordered and transmitted through a network. Thus, the invention can be used to implement sophisticated flow control rules so as to give preferential treatment to certain people, departments or computers.

Abstract: A method and system for distributing quantum cryptographic keys among a group of user devices through a switch connected to the user devices are provided. A switch [1000] establishes a connection between two user devices [405a, 405b] according to a schedule. A Quantum Key Distribution (QKD) session is established between the two user devices [405a, 405b] to facilitate sharing of secret key material between the two user devices. Connections and QKD sessions may be established for different pairs of the user devices.

Abstract: The present invention, which may be embodied in or carried out by various components of a data communications network, provides an improved criterion for tearing down network links. The invention allows network components to take into account the quality, status and performance of other network links, as well as the overall performance of the network, when deciding whether to remove a failing network from service.

Abstract: A first node (205) in a network includes a non-optical transceiver (415) and an optical subsystem (410). The non-optical transceiver (415) sends a request message to establish an optical link from the first node (205) to a second node via electrical signals over an electrically transmissive medium. The optical subsystem (410) establishes an optical link between the first node and the second node based on the receipt of the request granted message and transmits data between the first node and the second node via optical signals over the optical link.

Abstract: A wireless network (100) includes a communications node (120) configured to periodically generate and transmit at least one reception definition. Each reception definition indicates a time and manner in which the node will operate to receive information messages.

Abstract: The present invention is useful for routing data traffic in data communications networks where some or all of the network interface links are protected by cryptographic techniques, e.g., encryption. The invention routes datagram traffic in such networks toward interface links perceived to have strong encryption protection and away from interface links perceived to have weak or weakening encryption protection, based on the remaining encryption capacity for such links.

Abstract: A satellite network [100] includes backbone satellites [110]. The backbone satellites [110] act as routers for data units transmitted through network [100]. The backbone satellites [110] communicate with one another through inter-satellite links [111]. The satellite network [100] may further include user satellites [120] and ground stations [140]. The user satellites [120] may communicate with the backbone satellites [110] through omni-directional links [112].

Abstract: A quantum cryptographic device provides authentication services over the optical (quantum) channel and the public channel. In one implementation, polarizers generate optical pulses that have a polarization state based on a bit from a first bit sequence. A polarization rotator further rotates the polarization basis of the optical pulse by a rotation angle specified by one or more bits of a second bit sequence. A receiving device receives the modulated optical pulses, demodulates the pulses, and may determine whether the optical channel can be authenticated. In an alternate implementation, phase modulation, instead of polarization modulation, is used to similarly modulate the optical pulses.

Abstract: Methods and systems are disclosed in which information is securely transmitted in a network comprising untrusted network devices. Setup messages are sent to a networking device, and based on the setup messages, light directing devices are configured to direct light along a path from an origin endpoint to a terminal endpoint, thus providing a path through the network. Through the path, a stream of light information is sent using a plurality of light pulses to carry out quantum-cryptographic key distribution.

Abstract: A method, a device and a system for communications to and from a retro-reflector device (302) is provided. The retro-reflector device (302) receives a first frame (400) encoded in an input beam (106). The retro-reflector device (302) creates and sends a second frame (420) in a first reflected beam (108) formed by the retro-reflector device (302) reflecting the input beam (106) along a path closely aligned with a path of the input beam. At least one of the first frame (400) and the second frame (420) includes medium access control information. In some implementations, the first frame (400) may include a data throughput rate (404, 406), a preamble (402) and an error correction code (412).

Abstract: A method for operating a user communication device (18a, 18b, 19a, 19b), and a program and user communication device that operate in accordance with that method. An interface (2d, 2b, 23, 22) of the communication device (18a, 18b, 19a, 19b) is operated to enter identifiers identifying respective calling sources (18a, 18b, 19a, 19b) from which call signals may be received. The interface also is operated for entering into the device (18a, 18b, 19a, 19b) electrical signals representing corresponding audible signals that are to be individually generated in response to calls being received from the respective calling sources (18a, 18b, 19a, 19b). The identifiers are stored in a memory (2c, 24) in association with respective ones of the electrical signals.