Patent ID: 7917939

Claim:
An IPSec processing device that performs communications by encrypting IP packets exchanged between a first IP network and a second IP network, wherein the IPSec processing device includes a security policy database that stores security policies, wherein the security policy database includes a first security policy database, a second security policy database, and a third security policy database, wherein the first security policy database and the third security policy database include a linear list structure, wherein the second security policy database includes a hash list structure, wherein the IPSec processing device, when performing at least one of transmission and reception of the IP packet, retrieves a security policy to be applied to the IP packet in the order of the first security policy database, the second security policy database, and the third security policy database; and wherein the IPSec processing device stores security policies applied to system-based communications having higher priority than inter-user communications in the security policy databases as security policies for the system, and disposes the security policies for the system in positions preferentially retrieved.