Check Apt GPG will scan the already downloaded Release files cached by apt (and siblings) and will check that any needed GPG keys are available. Will print a GPG status for each repository found. If GPG keys are found to be missing, it will attempt to download the missing GPG key(s) from one of several large keyservers.
MX Linux stretch
MX Linux mx15
MX Linux stretch stretch/main: Updated from 19.01.23mx17+1 to 19.04.05mx17+1
MX Linux stretch stretch/main: Updated from 18.02.28mx17+1 to 19.01.23mx17+1
MX Linux stretch stretch/main: Version 18.02.28mx17+1 introduced
MX Linux mx15 mx15/main: Version 17.03mx15+1 introduced