I ran “apt-get update” on my Debian Box this morning and the following message appeared:

deb-sig-keys

W: GPG error: http://debian.indika.net.id unstable Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 010908312D230C5F
W: You may want to run apt-get update to correct these problems

I later found out that Debian had just updated their signature keys for 2006. The message simply means that the repository from where we are updating is NOT trusted.
Simple steps to make the repositories trusted:

Step 1: #wget http://ftp-master.debian.org/ziyi_key_2006.asc
Or, if you prefer you can download or save it from your browser.
Step 2: #apt-key add ziyi_key_2006.asc
Step 3: #apt-get update

That should work ; )