新安装的Ubuntu在使用sudo apt-get update更新源码的时候出现如下错误：
W: GPG 错误：http://ppa.launchpad.net precise Release: 由于没有公钥，无法验证下列签名： NO_PUBKEY 3EE66BD3F599ACE3 W: GPG 错误：http://ppa.launchpad.net precise Release: 由于没有公钥，无法验证下列签名： NO_PUBKEY 6AF0E1940624A220 W: 无法下载 bzip2:/var/lib/apt/lists/partial/mirrors.163.com_ubuntu_dists_precise_main_binary-i386_Packages Hash 校验和不符 W: 无法下载 bzip2:/var/lib/apt/lists/partial/mirrors.163.com_ubuntu_dists_precise-security_main_binary-i386_Packages Hash 校验和不符 W: 无法下载 bzip2:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_binary-amd64_Packages Hash 校验和不符 W: 无法下载 bzip2:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_binary-i386_Packages Hash 校验和不符 E: Some index files failed to download. They have been ignored, or old ones used instead.
解决方法很简单，下载导入公钥就行，下载导入key的命令如下：
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 6AF0E1940624A220 #此处6AF0E1940624A220需要是错误提示的key
此时继续更新发现没有公钥错误提示，但是还是效验存在问题，此时需要打开软件源的界面，将其他软件选项中的Canpnical合作伙伴/独立等四个选项取消勾选，再执行sudo apt-get update
此时发现可以顺利更新了。
sanbo@ubuntu:~/dev$ sudo apt-get update 命中 http://mirrors.163.com precise Release.gpg 命中 http://mirrors.163.com precise-updates Release.gpg 命中 http://mirrors.163.com precise-security Release.gpg 命中 http://mirrors.163.com precise Release 命中 http://mirrors.163.com precise-updates Release 命中 http://mirrors.163.com precise-security Release 命中 http://mirrors.163.com precise/main Sources 命中 http://mirrors.163.com precise/restricted Sources 命中 http://mirrors.163.com precise/universe Sources 命中 http://mirrors.163.com precise/multiverse Sources 命中 http://mirrors.163.com precise/main amd64 Packages 命中 http://mirrors.163.com precise/restricted amd64 Packages 命中 http://mirrors.163.com precise/universe amd64 Packages 命中 http://mirrors.163.com precise/multiverse amd64 Packages 命中 http://mirrors.163.com precise/main i386 Packages 命中 http://mirrors.163.com precise/restricted i386 Packages 命中 http://mirrors.163.com precise/universe i386 Packages 命中 http://mirrors.163.com precise/multiverse i386 Packages 命中 http://mirrors.163.com precise/main TranslationIndex 命中 http://mirrors.163.com precise/multiverse TranslationIndex 命中 http://mirrors.163.com precise/restricted TranslationIndex 命中 http://mirrors.163.com precise/universe TranslationIndex 命中 http://mirrors.163.com precise-updates/main Sources 命中 http://mirrors.163.com precise-updates/restricted Sources 命中 http://mirrors.163.com precise-updates/universe Sources 命中 http://mirrors.163.com precise-updates/multiverse Sources 命中 http://mirrors.163.com precise-updates/main amd64 Packages 命中 http://mirrors.163.com precise-updates/restricted amd64 Packages 命中 http://mirrors.163.com precise-updates/universe amd64 Packages 命中 http://mirrors.163.com precise-updates/multiverse amd64 Packages 命中 http://mirrors.163.com precise-updates/main i386 Packages 命中 http://mirrors.163.com precise-updates/restricted i386 Packages 命中 http://mirrors.163.com precise-updates/universe i386 Packages 命中 http://mirrors.163.com precise-updates/multiverse i386 Packages 命中 http://mirrors.163.com precise-updates/main TranslationIndex 命中 http://mirrors.163.com precise-updates/multiverse TranslationIndex 命中 http://mirrors.163.com precise-updates/restricted TranslationIndex 命中 http://mirrors.163.com precise-updates/universe TranslationIndex 命中 http://mirrors.163.com precise-security/main Sources 命中 http://mirrors.163.com precise-security/restricted Sources 命中 http://mirrors.163.com precise-security/universe Sources 命中 http://mirrors.163.com precise-security/multiverse Sources 命中 http://mirrors.163.com precise-security/main amd64 Packages 命中 http://mirrors.163.com precise-security/restricted amd64 Packages 命中 http://mirrors.163.com precise-security/universe amd64 Packages 命中 http://mirrors.163.com precise-security/multiverse amd64 Packages 命中 http://ppa.launchpad.net precise Release.gpg 命中 http://ppa.launchpad.net precise Release.gpg 命中 http://mirrors.163.com precise-security/main i386 Packages 命中 http://mirrors.163.com precise-security/restricted i386 Packages 命中 http://mirrors.163.com precise-security/universe i386 Packages 命中 http://mirrors.163.com precise-security/multiverse i386 Packages 命中 http://mirrors.163.com precise-security/main TranslationIndex 命中 http://mirrors.163.com precise-security/multiverse TranslationIndex 命中 http://mirrors.163.com precise-security/restricted TranslationIndex 命中 http://mirrors.163.com precise-security/universe TranslationIndex 获取：1 http://mirrors.163.com precise/main Translation-zh_CN [100 kB] 命中 http://mirrors.163.com precise/main Translation-en 获取：2 http://mirrors.163.com precise/multiverse Translation-zh_CN [6,476 B] 命中 http://mirrors.163.com precise/multiverse Translation-en 获取：3 http://mirrors.163.com precise/restricted Translation-zh_CN [2,620 B] 命中 http://mirrors.163.com precise/restricted Translation-en 获取：4 http://mirrors.163.com precise/universe Translation-zh_CN [139 kB] 命中 http://ppa.launchpad.net precise Release 命中 http://mirrors.163.com precise/universe Translation-en 获取：5 http://mirrors.163.com precise-updates/main Translation-zh_CN [100 kB] 命中 http://mirrors.163.com precise-updates/main Translation-en 获取：6 http://mirrors.163.com precise-updates/multiverse Translation-zh_CN [6,476 B] 命中 http://mirrors.163.com precise-updates/multiverse Translation-en 获取：7 http://mirrors.163.com precise-updates/restricted Translation-zh_CN [2,620 B] 命中 http://mirrors.163.com precise-updates/restricted Translation-en 获取：8 http://mirrors.163.com precise-updates/universe Translation-zh_CN [139 kB] 命中 http://mirrors.163.com precise-updates/universe Translation-en 命中 http://mirrors.163.com precise-security/main Translation-en 命中 http://mirrors.163.com precise-security/multiverse Translation-en 命中 http://mirrors.163.com precise-security/restricted Translation-en 命中 http://mirrors.163.com precise-security/universe Translation-en 命中 http://ppa.launchpad.net precise Release 命中 http://ppa.launchpad.net precise/main Sources 命中 http://ppa.launchpad.net precise/main amd64 Packages 命中 http://ppa.launchpad.net precise/main i386 Packages 忽略 http://ppa.launchpad.net precise/main TranslationIndex 命中 http://ppa.launchpad.net precise/main Sources 命中 http://ppa.launchpad.net precise/main amd64 Packages 命中 http://ppa.launchpad.net precise/main i386 Packages 忽略 http://ppa.launchpad.net precise/main TranslationIndex 忽略 http://ppa.launchpad.net precise/main Translation-zh_CN 忽略 http://ppa.launchpad.net precise/main Translation-zh 忽略 http://ppa.launchpad.net precise/main Translation-en_US 忽略 http://ppa.launchpad.net precise/main Translation-en 忽略 http://ppa.launchpad.net precise/main Translation-zh_CN 忽略 http://ppa.launchpad.net precise/main Translation-zh 忽略 http://ppa.launchpad.net precise/main Translation-en_US 忽略 http://ppa.launchpad.net precise/main Translation-en 下载 497 kB，耗时 7秒 (66.3 kB/s) 正在读取软件包列表... 完成
搞定收工！
另外送上一个163源，更新的速度挺不错，品种也挺全的:
# deb cdrom:[Ubuntu 12.04.1 LTS _Precise Pangolin_ - Release i386 (20120817.3)]/ precise main restricted # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://mirrors.163.com/ubuntu/ precise main restricted deb-src http://mirrors.163.com/ubuntu/ precise main restricted ## Major bug fix updates produced after the final release of the ## distribution. deb http://mirrors.163.com/ubuntu/ precise-updates main restricted deb-src http://mirrors.163.com/ubuntu/ precise-updates main restricted ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team. Also, please note that software in universe WILL NOT receive any ## review or updates from the Ubuntu security team. deb http://mirrors.163.com/ubuntu/ precise universe deb-src http://mirrors.163.com/ubuntu/ precise universe deb http://mirrors.163.com/ubuntu/ precise-updates universe deb-src http://mirrors.163.com/ubuntu/ precise-updates universe ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://mirrors.163.com/ubuntu/ precise multiverse deb-src http://mirrors.163.com/ubuntu/ precise multiverse deb http://mirrors.163.com/ubuntu/ precise-updates multiverse deb-src http://mirrors.163.com/ubuntu/ precise-updates multiverse ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://mirrors.163.com/ubuntu/ precise-security main restricted deb-src http://mirrors.163.com/ubuntu/ precise-security main restricted deb http://mirrors.163.com/ubuntu/ precise-security universe deb-src http://mirrors.163.com/ubuntu/ precise-security universe deb http://mirrors.163.com/ubuntu/ precise-security multiverse deb-src http://mirrors.163.com/ubuntu/ precise-security multiverse ## Uncomment the following two lines to add software from Canonical‘s ## ‘partner‘ repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. deb http://archive.canonical.com/ubuntu precise partner deb-src http://archive.canonical.com/ubuntu precise partner ## This software is not part of Ubuntu, but is offered by third-party ## developers who want to ship their latest software. deb http://extras.ubuntu.com/ubuntu precise main deb-src http://extras.ubuntu.com/ubuntu precise main # codeblock deb http://ppa.launchpad.net/pasgui/ppa/ubuntu precise main deb-src http://ppa.launchpad.net/pasgui/ppa/ubuntu precise main # ubuntu tweak deb http://ppa.launchpad.net/tualatrix/ppa/ubuntu precise main deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu precise main