Communication device and non-transitory computer-readable recording medium storing computer-readable instructions for communication device

A first communication device, wherein

• the first communication device supports a first version of an encrypted communication protocol and a second version of the encrypted communication protocol, the second version being newer than the first version,
• the first version is capable of using a first encryption scheme,
• the second version is capable of using the first encryption scheme and a second encryption scheme which is more secure than the first encryption scheme,
• the first communication device comprises a controller, and
• the controller is configured to:
• obtain a setting request related to the encrypted communication protocol;
• after the setting request has been obtained, receive candidate information from a second communication device, the candidate information including version information indicating a version of the encrypted communication protocol which the second communication device is capable of using and scheme information indicating an encryption scheme which the second communication device is capable of using;
• determine a target version and a target encryption scheme, the target version being a version of the encrypted communication protocol to be used in the encrypted communication with the second communication device, and the target encryption scheme being an encryption scheme to be used in the encrypted communication with the second communication device;
• and
• execute the encrypted communication with the second communication device by using the target version and the target encryption scheme,
• wherein in a case where a first setting request not including first version information indicating the first version but including second version information indicating the second version is obtained and first candidate information including the second version information and second scheme information indicating the second encryption scheme is received from the second communication device, the controller is configured to determine the second version as the target version and determine the second encryption scheme as the target encryption scheme,
• in a case where the first setting request is obtained and second candidate information including the second version information and first scheme information indicating the first encryption scheme but not including the second scheme information is received from the second communication device, the first encryption scheme is not determined as the target encryption scheme,
• in a case where a second setting request including the first version information and the second version information is obtained and the first candidate information is received from the second communication device, the controller is configured to determine the second version as the target version and determine the second encryption scheme as the target encryption scheme, and
• in a case where the second setting request is obtained and the second candidate information is received from the second communication device, the controller is configured to determine the second version as the target version and determine the first encryption scheme as the target encryption scheme.

A non-transitory computer-readable recording medium storing computer-readable instructions for a first communication device,

• wherein the first communication device supports a first version of an encrypted communication protocol and a second version of the encrypted communication protocol, the second version being newer than the first version,
• the first version is capable of using a first encryption scheme,
• the second version is capable of using the first encryption scheme and a second encryption scheme which is more secure than the first encryption scheme, and
• the computer-readable instructions, when executed by a processor of the first communication device, cause the first communication device to:
• obtain a setting request related to the encrypted communication protocol;
• after the setting request has been obtained, send setting information according to the setting request to a second communication device;
• and
• after the setting information has been sent to the second communication device, execute an encrypted communication with the second communication device by using a version and an encryption scheme that were determined by the second communication device based on the setting information,
• wherein in a case where a first setting request not including first version information indicating the first version but including second version information indicating the second version is obtained, first setting information is sent to the second communication device, the first setting information including the second version information and second scheme information indicating the second encryption scheme but not including first scheme information indicating the first encryption scheme, and
• in a case where a second setting request including the first version information and the second version information is obtained, second setting information is sent to the second communication device, the second setting information including the first version information, the second version information, the first scheme information, and the second scheme information.

A non-transitory computer-readable recording medium storing computer-readable instructions for a first communication device,

• wherein the first communication device supports a first version of an encrypted communication protocol and a second version of the encrypted communication protocol, the second version being newer than the first version,
• the first version is capable of using a first encryption scheme,
• the second version is capable of using the first encryption scheme and a second encryption scheme which is more secure than the first encryption scheme, and
• the computer-readable instructions, when executed by a processor of the first communication device, cause the first communication device to:
• obtain a setting request related to the encrypted communication protocol;
• after the setting request has been obtained, receive candidate information from a second communication device, the candidate information including version information indicating a version of the encrypted communication protocol which the second communication device is capable of using and scheme information indicating an encryption scheme which the second communication device is capable of using;
• determine a target version and a target encryption scheme, the target version being a version of the encrypted communication protocol to be used in the encrypted communication with the second communication device, and the target encryption scheme being an encryption scheme to be used in the encrypted communication with the second communication device;
• and
• execute the encrypted communication with the second communication device by using the target version and the target encryption scheme,
• wherein in a case where a first setting request not including first version information indicating the first version but including second version information indicating the second version is obtained and first candidate information including the second version information and second scheme information indicating the second encryption scheme is received from the second communication device, the second version is determined as the target version and the second encryption scheme is determined as the target encryption scheme,
• in a case where the first setting request is obtained and second candidate information including the second version information and first scheme information indicating the first encryption scheme but not including the second scheme information is received from the second communication device, the first encryption scheme is not determined as the target encryption scheme,
• in a case where a second setting request including the first version information and the second version information is obtained and the first candidate information is received from the second communication device, the second version is determined as the target version and the second encryption scheme is determined as the target encryption scheme, and
• in a case where the second setting request is obtained and the second candidate information is received from the second communication device, the second version is determined as the target version and the first encryption scheme is determined as the target encryption scheme.