Abstract: Disclosed is a method for encrypted communications. A first IPsec endpoint selects a security association (SA) from a security association database (SAD) by using a selector and then extracts an indexing parameter from SA. The indexing parameter is used to determine an active key location from a key storage database (KSD). Data packets are then encrypted using a key from the active key location. The first IPsec endpoint also forms a security parameter index (SPI) in a header of the data packet by using a keyID from the active key location and transmits the encrypted data packet with the header indicating the SPI to a second IPsec endpoint.

Abstract: A sending device generates a first and a second KMM, wherein the first KMM includes a first KEK and a KMM encryption key, and the second KMM includes a set of symmetric encryption keys. The sending device further encrypts the set of symmetric encryption keys using the first KEK; encrypts the first KEK and the KMM encryption key using a first public key of a receiving device; and encrypts the second KMM using the KMM encryption key to generate an encrypted second KMM before sending the first KMM and the encrypted second KMM to the receiving device. The receiving device decrypts the first KEK and the KMM encryption key using a first private key that corresponds to the first public key; and decrypts the encrypted second KMM using the KMM encryption key to obtain the encrypted set of symmetric keys.

Abstract: A method for managing a packet in a communication system between two or more endpoints, a sender and one or more recipients, comprises receiving a first packet comprising a source identifier that uniquely identifies a sender of the first packet and a current source time assigned to the first packet by the sender, determining a received time for the first packet, retrieving a cached source time assigned by the sender to a second packet that was received prior to receiving the first packet, and determining whether to discard or process the first packet based on the current source time, the received time, and the cached source time. The current source time, the received time, and the cached time, in addition to predetermined parameters such as a maximum age and an anti-replay window allows a recipient to determine whether to process or discard a packet.

Abstract: A method and system include de-keying a base station in a conventional TDMA communications system and staffing a timer in the base station when the base station de-keys. The method and system further include receiving a transmission from a mobile station and re-keying and repeating the transmission, if the transmission is received with proper synchronization before expiration of the timer.

Abstract: In a TDMA system whereby the TDMA system comprises a plurality of subscriber units and a plurality of base radios, a method and system for providing access to a channel for voice transmissions where the first subscriber unit determines whether it is provisioned for polite access to the channel. In addition, the first subscriber unit is characterized by a first color code and a first talkgroup ID. The first subscriber unit also examines the voice transmissions on the channel for voice transmissions that are from a second subscriber unit with a second color code and a second talkgroup ID. If the first color code and the second color code match and if the first talkgroup ID and the second talkgroup match, then the first subscriber unit is allowed access to the channel for voice transmissions even though the channel is being used for voice transmissions by the second subscriber unit.

Abstract: A method and system for scanning a TDMA channel by a subscriber unit in a wireless communications landscape 100 is disclosed. The subscriber unit locks onto a channel that is preprogrammed in the subscriber unit. A base radio transmits a control message to the subscriber unit. The control message informs the subscriber unit of activity present on the channel. The subscriber unit receives and decodes the control message to determine whether there is activity on the channel. If there is, the subscriber unit determines whether the activity is of interest. If it is, then the subscriber unit remains on the channel to receive the activity present on the channel.

Abstract: Methods are described that enable host devices of a multicast IP network to reliably join multicast group address(es) in talkgroup or point-to-point calls. For a talkgroup call, a sourcing host sends “hello” packets or payload to one or more network devices, addressed to a multicast group address. The receiving host issues a join command to the one or more network devices in an attempt to reliably join the multicast group address. If any packets are received by the receiving host within a designated time period associated with the attempt, the receiving host is reliably joined to the multicast group address. For a point-to-point call, a controller sends a pair of multicast group addresses, one designated for sourcing packets and the other designated for receiving packets, to a first and second host participating in the point-to-point call. The designated “source” and “receive” multicast group address are complementary for the first and second hosts.

Abstract: Methods are described that enable host devices of a multicast IP network to reliably join multicast group address(es) in talkgroup or point-to-point calls. For a talkgroup call, a sourcing host sends “hello” packets or payload to one or more network devices, addressed to a multicast group address. The receiving host issues a join command to the one or more network devices in an attempt to reliably join the multicast group address. If any packets are received by the receiving host within a designated time period associated with the attempt, the receiving host is reliably joined to the multicast group address. For a point-to-point call, a controller sends a pair of multicast group addresses, one designated for sourcing packets and the other designated for receiving packets, to a first and second host participating in the point-to-point call. The designated “source” and “receive” multicast group address are complementary for the first and second hosts.