guruuser@GRU01DBS01TEST:/etc/apt$ sudo apt-key list
/etc/apt/trusted.gpg
--------------------
pub 1024D/437D05B5 2004-09-12
uid Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
sub 2048g/79164387 2004-09-12
pub 1024D/FBB75451 2004-12-30
uid Ubuntu CD Image Automatic Signing Key <cdimage@ubuntu.com>
pub 4096R/C0B21F32 2012-05-11
uid Ubuntu Archive Automatic Signing Key (2012) <ftpmaster@ubuntu.com>
pub 4096R/EFE21092 2012-05-11
uid Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>
gpg: [don't know]: invalid packet (ctb=2d)
gpg: keydb_search_next failed: invalid packet
guruuser@GRU01DBS01TEST:/etc/apt$
guruuser@GRU01DBS01TEST:/etc/apt$
guruuser@GRU01DBS01TEST:/etc/apt$ sudo mv trustdb.gpg trustdb.gpg.old
guruuser@GRU01DBS01TEST:/etc/apt$
guruuser@GRU01DBS01TEST:/etc/apt$
guruuser@GRU01DBS01TEST:/etc/apt$ sudo apt-key list
gpg: /etc/apt/trustdb.gpg: trustdb created
/etc/apt/trusted.gpg
--------------------
pub 1024D/437D05B5 2004-09-12
uid Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
sub 2048g/79164387 2004-09-12
pub 1024D/FBB75451 2004-12-30
uid Ubuntu CD Image Automatic Signing Key <cdimage@ubuntu.com>
pub 4096R/C0B21F32 2012-05-11
uid Ubuntu Archive Automatic Signing Key (2012) <ftpmaster@ubuntu.com>
pub 4096R/EFE21092 2012-05-11
uid Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>
gpg: [don't know]: invalid packet (ctb=2d)
gpg: keydb_search_next failed: invalid packet