W: GPG error: http://security.debian.org jessie/updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9D6D8F6BC857C906 NO_PUBKEY 8B48AD6246925553
Reading package lists...
Building dependency tree...
The following packages will be upgraded:
ubuntu-keyring
1 upgraded, 0 newly installed, 0 to remove and 87 not upgraded.
Need to get 16.7 kB of archives.
After this operation, 5120 B of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu/ precise-updates/main ubuntu-keyring all 2011.11.21.1 [16.7 kB]
Hit http://security.debian.org jessie/updates/main Translation-en
Hit http://archive.ubuntu.com precise/main Translation-en
Hit http://archive.ubuntu.com precise/restricted Translation-en
Fetched 63.1 kB in 1s (59.3 kB/s)
Reading package lists...
W: GPG error: http://security.debian.org jessie/updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9D6D8F6BC857C906 NO_PUBKEY 8B48AD6246925553