I get some errors when trying to update the package list with sudo apt-get update
command, specifically the error messages are as follows:
W: GPG error: http://dl.google.com stable Release: The following signatures were invalid: BADSIG A040830F7FAC5991 Google, Inc. Linux Package Signing Key W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://archive.canonical.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://extras.ubuntu.com precise Release: The following signatures were invalid: BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key W: Failed to fetch http://archive.canonical.com/ubuntu/dists/precise/Release W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/Release W: Some index files failed to download. They have been ignored, or old ones used instead.
I'm using Kubuntu 12.04.
EDIT
I performed the commands suggested by terdon in his answer, but it still doesn't work; when trying to update the keys, I got the following output:
Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /tmp/tmp.OE3Vb6NDgl --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --recv-keys --keyserver keyserver.ubuntu.com A040830F7FAC5991 gpg: requesting key 7FAC5991 from hkp server keyserver.ubuntu.com gpg: key 7FAC5991: "Google, Inc. Linux Package Signing Key " not changed gpg: Total number processed: 1 gpg: unchanged: 1 Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /tmp/tmp.QFmVRIYHrE --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --recv-keys --keyserver keyserver.ubuntu.com 40976EAF437D05B5 gpg: requesting key 437D05B5 from hkp server keyserver.ubuntu.com gpg: key 437D05B5: "Ubuntu Archive Automatic Signing Key " not changed gpg: Total number processed: 1 gpg: unchanged: 1 Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /tmp/tmp.kJGIgNoOEW --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --recv-keys --keyserver keyserver.ubuntu.com 16126D3A3E5C1192 gpg: requesting key 3E5C1192 from hkp server keyserver.ubuntu.com gpg: key 3E5C1192: "Ubuntu Extras Archive Automatic Signing Key " not changed gpg: Total number processed: 1 gpg: unchanged: 1
And trying to use sudo apt-get update
still gives me the same errors as before.