Ubuntu public key is not available

I use Ubuntu 10.04 as my system operation. When use command apt-get update in terminal, I get error message :

The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5

If we get error message Ubuntu public key is not available, It means that my APT doesn’t have needed the public key. In the example above, finger print of the public key is 40976EAF437D05B5. To solve Ubuntu public key is not available problem, we can use command :

gpg –keyserver hkp://subkeys.pgp.net –recv-keys KEY
gpg –export –armor KEY | sudo apt-key add –

This is a full command to solve at Ubuntu public key is not available, type this text in terminal :

gpg –keyserver hkp://subkeys.pgp.net –recv-keys 40976EAF437D05B5
gpg –export –armor 40976EAF437D05B5 | sudo apt-key add –