# If you are seeing ...

Reading package lists... Done
W: GPG error: http://security.debian.org stable/updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A70DAF536070D3A1
W: GPG error: http://http.us.debian.org stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A70DAF536070D3A1 NO_PUBKEY B5D0C804ADB11277
W: You may want to run apt-get update to correct these problems

# You can try

debian:~# gpg --keyserver wwwkeys.eu.pgp.net --recv-keys A70DAF536070D3A1
debian:~# gpg --keyserver wwwkeys.eu.pgp.net --recv-keys B5D0C804ADB11277
debian:~# gpg --armor --export A70DAF536070D3A1 | sudo apt-key add -
debian:~# gpg --armor --export B5D0C804ADB11277 | sudo apt-key add -