In computers based on a Debian operating system that uses Linux kernel, error messages similar to NO_PUBKEY may appear. This happens while using the Apt-Get command line tool, and this error is associated with the tool's update feature. This problem can be solved by simply keying in the appropriate commands.
To solve the Apt-get : NO_PUBKEY / GPG error in Debian, simply type the following commands, taking care to replace the number below with that of the key that was displayed in the error message:
gpg --keyserver pgpkeys.mit.edu --recv-key 010908312D230C5F gpg -a --export 010908312D230C5F | sudo apt-key add -