Signatures couldn't be verified because the public key is not available: NO_PUBKEY

Eror PPA for GNOME Do Core Team ERROR:

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Reading package lists... Done
W: GPG error: http://ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 423A2125D782A00F
Reading package lists... Done

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Solution:

apt-get update 2> /tmp/keymissing; for key in $(grep "NO_PUBKEY" /tmp/keymissing |sed "s/.*NO_PUBKEY //"); do echo -e "\nProcessing key: $key"; gpg --keyserver subkeys.pgp.net --recv $key && sudo gpg --export --armor $key | apt-key add -; done