Patent ID: 9525670
Filing Date: 2016-12-20
CPC Classification: H04L

Claim Text:
1. A non-transitory computer-readable recording medium storing therein a communication program that causes a computer to execute a process comprising: receiving from a communication counterpart apparatus encrypted data and identification information of a first key with which the encrypted data was encrypted, the first key being one of a plurality of keys used for a common key encryption between the computer and the communication counterpart apparatus; determining whether identification information of a key to be used subsequent to the first key is stored and correlated with the identification information of the first key, based on the identification information of the first key and by referring to a storing unit of the computer storing the plurality of keys and identification information corresponding to the plurality of the keys thereof; obtaining a second key and identification information of the second key when the identification information of the key is not stored according to the determining, the second key being one of the plurality of keys and different from the first key; storing and correlating the identification information of the second key with the identification information of the first key; encrypting the second key and the identification information of the second key with the first key; and transmitting the encrypted second key, the encrypted identification information of the second key, and the identification information of the first key to the communication counterpart apparatus.