$ sudo apt-get install build-essential
[sudo] password for mypc:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
dpkg-dev g++ g++-4.4 libstdc++6-4.4-dev xz-utils
Suggested packages:
debian-keyring debian-maintainers g++-multilib g++-4.4-multilib gcc-4.4-doc
libstdc++6-4.4-dbg libstdc++6-4.4-doc
The following NEW packages will be installed:
build-essential dpkg-dev g++ g++-4.4 libstdc++6-4.4-dev xz-utils
0 upgraded, 6 newly installed, 0 to remove and 0 not upgraded.
Need to get 8,173kB of archives.
After this operation, 26.2MB of additional disk space will be used.
Do you want to continue [Y/n]? Y
WARNING: The following packages cannot be authenticated!
libstdc++6-4.4-dev g++-4.4 g++ xz-utils dpkg-dev build-essential
Install these packages without verification [y/N]? N
E: Some packages could not be authenticated
$ sudo apt-get install debian-archive-keyring
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
debian-archive-keyring
0 upgraded, 1 newly installed, 0 to remove and 10 not upgraded.
Need to get 13.1kB of archives.
After this operation, 65.5kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
debian-archive-keyring
Install these packages without verification [y/N]? N
E: Some packages could not be authenticated