Patent ID: 7558956

Claim:
A communications device that performs encrypted communications by establishing, based on IPsec (IP security protocol) and IKE (Internet Key Exchange), an ISAKMP (Internet Security Association and Key Management Protocol) SA (Security Association) and an IPsec SA, comprising: a managing unit that stores an identifier of another communications device with which said encrypted communications is performed; an identifier of an IPsec SA established with that other communications device; and an identifier of an ISAKMP SA established with that other communications device; a judging unit that, from among ISAKMP SAs whose identifiers are stored by said managing unit, specifies one or a plurality of ISAKMP SAs established with the other communications device and satisfying an IPsec SA Delete Payload transmission condition stored by said managing unit; a transmitting unit that uses the ISAKMP SAs specified by said judging unit to transmit a Delete Payload of the IPsec SA; and a deleting unit that deletes from said managing unit the identifier of the IPsec SA to be deleted by the Delete Payload, wherein, the transmission condition is that the Delete Payload of the IPsec SA should be transmitted using all the ISAKMP SAs established with the other communications device.