Notice how the output when you run apt-get update only has precise-security. I would expect there to be lines that say precise in addition to the lines that say precise-security.
Are you having trouble installing any other software? What does your /etc/apt/sources.list file look like?
Here is an example sources.list file.
For dpkg-sig, you should at least have the following lines in sources.list:
deb http://us.archive.ubuntu.com/ubuntu/ precise universe
deb http://us.archive.ubuntu.com/ubuntu/ precise-updates universe
If you edit sources.list, make sure you run sudo apt-get update again.