How to solve "The following packages cannot be authenticated"

How to solve "The following packages cannot be authenticated"



Users of Debian's testing or unstable distributions may be noticing messages from apt saying things like:



WARNING: The following packages cannot be authenticated!



foo bar baz



Install these packages without verification [y/N]?



I noticed today that google doesn't turn up good hits for the fix. The fix is really simple:



apt-get install debian-archive-keyring

apt-get update