一般出现这个问题基本上都是都是因为想要装ibus输入法，添加了ppa的源，例如： GPG error: http://ppa.launchpad.net jaunty Release: The following signatures The last 3 times I have updated, this missing key keeps coming up. Can some one direct me to the public key? W: GPG error: http://ppa.launchpad.net jaunty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 632D16BB0C713DA6 解决方法是 执行下面两行命令 $gpg [...]