Verifying debian images signatures and checksums

Install debian-keyring

( for sum in MD5SUMS SHA1SUMS SHA256SUMS SHA512SUMS; do LANG=C gpg --keyring /usr/share/keyrings/debian-role-keys.gpg --verify debian-8.5.0-openstack.$sum.sign; done; )

More details in blog post

http://www.LuftHans.com/node/5707