Patent ID: 9455827
Filing Date: 2016-09-27
CPC Classification: H04L

Claim Text:
1. A communication apparatus comprising: a cryptographic key storage configured to store therein one or more cryptographic keys shared with an external device; a transmitter configured to transmit first specifying information that specifies at least one of the cryptographic keys to the external device, the first specifying information including at least identification information and a hash value of the cryptographic key, the identification information identifying the cryptographic key; a receiver configured to receive determination information that indicates a result of determination, which is made by the external device based on the first specifying information, on whether the shared cryptographic key is consistent between the apparatus and the external device; and a sharing controller configured to, when receiving the determination information indicating that the shared cryptographic key is inconsistent between the apparatus and the external device, delete the cryptographic key identified by the identification information included in the first specifying information from the cryptographic key storage; wherein when receiving the determination information indicating that the shared cryptographic key is inconsistent between the apparatus and the external device, the transmitter transmits, to the external device, second specifying information that specifies at least one of the cryptographic keys other than the cryptographic keys identified by the identification information included in the first specifying information, and the cryptographic key storage stores therein a cryptographic key generated by quantum key distribution with the external device.