When i try to install or update any packages I get:
Untrusted packages could compromise your system's security.
You should only proceed with the installation if you are certain that
this is what you want to do.
I strongly suspect this is related to the error i get on update:
$ sudo aptitude update
Get: 1 http://ftp.us.debian.org wheezy InRelease [208 kB]
Get: 2 http://debian.lcs.mit.edu wheezy InRelease [208 kB]
Ign http://ftp.us.debian.org wheezy InRelease
Hit http://ftp.us.debian.org wheezy/main amd64 Packages/DiffIndex
Hit http://ftp.us.debian.org wheezy/contrib amd64 Packages/DiffIndex
Hit http://ftp.us.debian.org wheezy/non-free amd64 Packages/DiffIndex
Hit http://ftp.us.debian.org wheezy/contrib Translation-en
Hit http://ftp.us.debian.org wheezy/main Translation-en
Hit http://ftp.us.debian.org wheezy/non-free Translation-en
Get: 3 http://debian.lcs.mit.edu wheezy-updates InRelease [116 kB]
Ign http://debian.lcs.mit.edu wheezy InRelease
Ign http://debian.lcs.mit.edu wheezy-updates InRelease
Hit http://debian.lcs.mit.edu wheezy/main Sources/DiffIndex
Hit http://debian.lcs.mit.edu wheezy/main amd64 Packages/DiffIndex
Hit http://debian.lcs.mit.edu wheezy/main Translation-en
Ign http://ftp.us.debian.org wheezy/contrib Translation-en_US
Ign http://debian.lcs.mit.edu wheezy-updates/main Sources/DiffIndex
Ign http://debian.lcs.mit.edu wheezy-updates/main amd64 Packages/DiffIndex
Ign http://ftp.us.debian.org wheezy/main Translation-en_US
Ign http://ftp.us.debian.org wheezy/non-free Translation-en_US
Hit http://debian.lcs.mit.edu wheezy-updates/main Sources
Hit http://debian.lcs.mit.edu wheezy-updates/main amd64 Packages
Ign http://debian.lcs.mit.edu wheezy/main Translation-en_US
Ign http://debian.lcs.mit.edu wheezy-updates/main Translation-en_US
Ign http://debian.lcs.mit.edu wheezy-updates/main Translation-en
Fetched 531 kB in 1s (304 kB/s)
W: GPG error: http://ftp.us.debian.org wheezy InRelease: Unknown error executing gpgv
W: GPG error: http://debian.lcs.mit.edu wheezy InRelease: Unknown error executing gpgv
W: GPG error: http://debian.lcs.mit.edu wheezy-updates InRelease: Unknown error executing gpgv
I have tried reinstalling the key ring:
sudo aptitude reinstall debian-archive-keyring
(which surprisingly doesn't cause a warning).