I have a Debian Squeeze EC2 AMI. On booting up an instance with it and trying to install packages with apt-get I get errors saying there is no keyring installed. Here is the error with apt-get update:

root@ip:~# apt-get update
Get:1 http://ftp.us.debian.org squeeze Release.gpg [1672 B]
Ign http://ftp.us.debian.org/debian/ squeeze/contrib Translation-en
Ign http://ftp.us.debian.org/debian/ squeeze/main Translation-en
Ign http://ftp.us.debian.org/debian/ squeeze/non-free Translation-en
Get:2 http://security.debian.org squeeze/updates Release.gpg [836 B]          
Ign http://security.debian.org/ squeeze/updates/contrib Translation-en                                  
Ign http://security.debian.org/ squeeze/updates/main Translation-en           
Hit http://ftp.us.debian.org squeeze Release                                  
Ign http://ftp.us.debian.org squeeze Release                                                         
Ign http://security.debian.org/ squeeze/updates/non-free Translation-en                              
Ign http://ftp.us.debian.org squeeze/main Sources/DiffIndex                                         
Get:3 http://security.debian.org squeeze/updates Release [86.9 kB]                                  
Ign http://security.debian.org squeeze/updates Release                         
Ign http://ftp.us.debian.org squeeze/contrib Sources/DiffIndex          
Ign http://ftp.us.debian.org squeeze/non-free Sources/DiffIndex
Ign http://ftp.us.debian.org squeeze/main amd64 Packages/DiffIndex
Ign http://ftp.us.debian.org squeeze/contrib amd64 Packages/DiffIndex
Ign http://ftp.us.debian.org squeeze/non-free amd64 Packages/DiffIndex
Ign http://security.debian.org squeeze/updates/main Sources/DiffIndex
Hit http://ftp.us.debian.org squeeze/main Sources                    
Hit http://ftp.us.debian.org squeeze/contrib Sources
Hit http://ftp.us.debian.org squeeze/non-free Sources
Hit http://ftp.us.debian.org squeeze/main amd64 Packages             
Hit http://ftp.us.debian.org squeeze/contrib amd64 Packages          
Ign http://security.debian.org squeeze/updates/contrib Sources/DiffIndex
Ign http://security.debian.org squeeze/updates/non-free Sources/DiffIndex
Ign http://security.debian.org squeeze/updates/main amd64 Packages/DiffIndex
Ign http://security.debian.org squeeze/updates/contrib amd64 Packages/DiffIndex
Ign http://security.debian.org squeeze/updates/non-free amd64 Packages/DiffIndex
Hit http://ftp.us.debian.org squeeze/non-free amd64 Packages         
Get:4 http://backports.debian.org squeeze-backports Release.gpg [836 B]
Ign http://backports.debian.org/debian-backports/ squeeze-backports/main Translation-en
Hit http://security.debian.org squeeze/updates/main Sources
Hit http://security.debian.org squeeze/updates/contrib Sources
Hit http://security.debian.org squeeze/updates/non-free Sources
Hit http://security.debian.org squeeze/updates/main amd64 Packages
Hit http://security.debian.org squeeze/updates/contrib amd64 Packages
Hit http://security.debian.org squeeze/updates/non-free amd64 Packages
Get:5 http://backports.debian.org squeeze-backports Release [77.6 kB]
Ign http://backports.debian.org squeeze-backports Release
Hit http://backports.debian.org squeeze-backports/main amd64 Packages/DiffIndex
Hit http://backports.debian.org squeeze-backports/main amd64 Packages
Fetched 3346 B in 0s (5298 B/s)
Reading package lists... Done
W: GPG error: http://ftp.us.debian.org squeeze Release: No keyring installed in /etc/apt/trusted.gpg.d/.
W: GPG error: http://security.debian.org squeeze/updates Release: No keyring installed in /etc/apt/trusted.gpg.d/.
W: GPG error: http://backports.debian.org squeeze-backports Release: No keyring installed in /etc/apt/trusted.gpg.d/.

Googling around didn't really help me fix this problem. I tried installing the packages "debian-keyring" and "debian-archive-keyring" but the error does not go away. I'd like to avoid installing unstrusted packages. Any help is appreciated! Why does this error happen and where can I learn more?