我有一台Linux Mint 17（Qiana）机器，它从Linux Mint 14更新到15到16到17.目前，apt-get更新始终失败（现在已经持续数周），并显示以下错误消息：
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://packages.linuxmint.com qiana Release: The following signatures were invalid: BADSIG 3EE67F3D0FF405B2 Clement Lefebvre (Linux Mint Package Repository v1) <root@linuxmint.com>
W: Failed to fetch http://packages.linuxmint.com/dists/qiana/Release
W: Some index files failed to download. They have been ignored, or old ones used instead.
这里有什么问题？
我看到类似的问题被关闭为“如何更改我的源列表”的重复 - 这不是我要问的，我知道如何编辑/etc/apt/sources.list文件。如果解决方案是对该文件的特定更改，我很乐意知道。
对于它的价值，这些是我的/etc/apt/sources.list文件的内容：
deb http://packages.linuxmint.com/ qiana main upstream import
# deb http://archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ trusty main
deb http://archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://archive.canonical.com/ubuntu/ trusty partner
deb http://cran.rstudio.com/bin/linux/ubuntu trusty/
# deb http://archive.getdeb.net/ubuntu trusty-getdeb apps
# deb http://archive.getdeb.net/ubuntu trusty-getdeb games
# deb-src http://packages.mate-desktop.org/repo/ubuntu precise main