NO_PUBKEY 9AA38DCD55BE302B

W: GPG error: http://mirrors.163.com unstable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9AA38DCD55BE302B
W: You may want to run apt-get update to correct these problems




To be executed as root:

gpg --keyserver pgpkeys.pca.dfn.de --recv-keys 9AA38DCD55BE302B
gpg --fingerprint 9AA38DCD55BE302B
# compare the fingerprint with a fingerprint on a machine with a trust path
gpg --export -a 9AA38DCD55BE302B| apt-key add -

This is for a different key, but besides that, that's it - and you may use a
different keyserver.