GPG error when update 'Software Sources'

[yinglcs2]

Hi,

I Go to 'Settings' in Update Manger', I check the
* Canonical-supported Open Source
* Community-maintainted Open Soruce

But when I click 'Close' I get the following error
And I see the following GPG error.

Can you please tell me how can I fix it?

Thank you.




W: GPG error: http://dl.google.com stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A040830F7FAC5991
W: GPG error: http://archive.canonical.com natty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://security.ubuntu.com natty-security Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5

W: GPG error: http://us.archive.ubuntu.com natty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://us.archive.ubuntu.com natty-updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/Release

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/natty-updates/Release

W: Some index files failed to download. They have been ignored, or old ones used instead.

[lindsay7]

Do the following for the keys that you need,
NO_PUBKEY A040830F7FAC5991 and NO_PUBKEY 40976EAF437D05B5
, see the example. Run these in the terminal.

Code:
gpg --keyserver subkeys.pgp.net --recv KEY
gpg --export --armor KEY | sudo apt-key add -
When you get an error message, replace the word "KEY" with the numbers in the eror message. For your error you would enter this command
Code:
gpg --keyserver subkeys.pgp.net --recv F120156012B83718
After you press enter and it sends the command, you would enter the second line
Code:
gpg --export --armor F120156012B83718 | sudo apt-key add -


then type in the folling

sudo apt-get update

and


sudo apt-get upgrade

[yinglcs2]

Thanks.
But when I tried the commands, I get this:



$ gpg --keyserver subkeys.pgp.net --recv 40976EAF437D05B5
gpg: requesting key 437D05B5 from hkp server subkeys.pgp.net
gpg: keyserver timed out
gpg: keyserver receive failed: keyserver error


$ gpg --keyserver subkeys.pgp.net --recv A040830F7FAC5991
gpg: requesting key 7FAC5991 from hkp server subkeys.pgp.net
gpg: keyserver timed out
gpg: keyserver receive failed: keyserver error

[lindsay7]

try this, just use the last 8 digits of the key,

Code:
gpg --keyserver keyserver.ubuntu.com --recv 437D05B5
gpg --export --armor 437D05B5 | sudo apt-key add -
then run
Code:
sudo apt-get update