EXPKEYSIG F42ED6FBAB17C654 [closed]

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I coudn't install new ROS package to my PC. And here is my log (something wrong with GPG ?)

Is there any solutions?

Environment; OS : ubuntu 18.04 ROS : 18.04

$ sudo apt update
Hit:1 http://archive.raspberrypi.org/debian jessie InRelease                                                  
Hit:2 http://ports.ubuntu.com/ubuntu-ports bionic InRelease                                                   
Hit:3 http://ports.ubuntu.com/ubuntu-ports bionic-updates InRelease                                        
Hit:4 http://packages.ros.org/ros/ubuntu bionic InRelease                            
Hit:5 http://ports.ubuntu.com/ubuntu-ports bionic-backports InRelease
Hit:6 http://ports.ubuntu.com/ubuntu-ports bionic-security InRelease
Err:4 http://packages.ros.org/ros/ubuntu bionic InRelease
  The following signatures were invalid: EXPKEYSIG F42ED6FBAB17C654 Open Robotics <info@osrfoundation.org>
Reading package lists... Done
Building dependency tree       
Reading state information... Done
119 packages can be upgraded. Run 'apt list --upgradable' to see them.
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://packages.ros.org/ros/ubuntu bionic InRelease: The following signatures were invalid: EXPKEYSIG F42ED6FBAB17C654 Open Robotics <info@osrfoundation.org>
W: Failed to fetch http://packages.ros.org/ros/ubuntu/dists/bionic/InRelease  The following signatures were invalid: EXPKEYSIG F42ED6FBAB17C654 Open Robotics <info@osrfoundation.org>
W: Some index files failed to download. They have been ignored, or old ones used instead.