A communication device collects encrypted packet data passing through the communication device. The communication device extracts parameters required to generate a decryption key used when the collected packet data is decrypted. The communication device notifies a key managing device of the extracted parameters. The communication device acquires the decryption key, generated by the key managing device using the parameters of which notification has been given, from the key managing device. The communication device decrypts the collected packet data using the acquired decryption key and analyzes the decrypted packet data. The communication device extracts profile information from the analyzed packet data. The communication device transmits the extracted profile information and network information related to a network through which the encrypted packet data passes to a communication log device as a communication log.