參考資訊：
https://elkano.org/blog/debian-8-jessie-signatures-verified-public-key/
解決方式如下：
$ wget -O - https://ftp-master.debian.org/keys/archive-key-8.asc | sudo apt-key add - $ wget -O - https://ftp-master.debian.org/keys/archive-key-8-security.asc | sudo apt-key add - $ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 8B48AD6246925553 $ aptitude install debian-keyring debian-archive-keyring $ sudo apt-get update