root@free:~# apt-get update
Get:1 http://security.debian.org wheezy/updates Release.gpg [1,554 B]
Get:2 http://ftp.debian.org wheezy Release.gpg [2,390 B]
Get:3 http://security.debian.org wheezy/updates Release [102 kB]
Get:4 http://ftp.debian.org wheezy Release [168 kB]
Get:5 http://security.debian.org wheezy/updates/main amd64 Packages [318 kB]
Get:6 http://ftp.debian.org wheezy/main amd64 Packages [5,841 kB]
Get:7 http://security.debian.org wheezy/updates/contrib amd64 Packages [14 B]
Get:8 http://security.debian.org wheezy/updates/non-free amd64 Packages [14 B]
Get:9 http://security.debian.org wheezy/updates/main i386 Packages [321 kB]
Get:10 http://security.debian.org wheezy/updates/contrib i386 Packages [14 B]
Get:11 http://security.debian.org wheezy/updates/non-free i386 Packages [14 B]
Get:12 http://security.debian.org wheezy/updates/contrib Translation-en [523 B]
Get:13 http://security.debian.org wheezy/updates/main Translation-en [182 kB]
Get:14 http://security.debian.org wheezy/updates/non-free Translation-en [14 B]
Get:15 http://ftp.debian.org wheezy/contrib amd64 Packages [42.0 kB]
Get:16 http://ftp.debian.org wheezy/non-free amd64 Packages [80.8 kB]
Get:17 http://ftp.debian.org wheezy/main i386 Packages [5,859 kB]
Get:18 http://ftp.debian.org wheezy/contrib i386 Packages [42.3 kB]
Get:19 http://ftp.debian.org wheezy/non-free i386 Packages [77.6 kB]
Get:20 http://ftp.debian.org wheezy/contrib Translation-en [34.8 kB]
Get:21 http://ftp.debian.org wheezy/main Translation-en [3,848 kB]
Get:22 http://ftp.debian.org wheezy/non-free Translation-en [66.1 kB]
Fetched 17.0 MB in 1min 33s (182 kB/s)
Reading package lists... Done
W: There is no public key available for the following key IDs:
9D6D8F6BC857C906
W: There is no public key available for the following key IDs:
7638D0442B90D010

Надо установить старые ключи

apt-get install debian-keyring debian-archive-keyring
apt-key update