The manual page and help for the apt-key linux command. Apt-key is a command to manage the list of keys used by apt to authenticate packages. Packages authenticated with these keys can be considered trusted. Note that if you need to use apt-key, you will need to install the GNU Privacy Guard tool, which is included in the gnupg package. For this reason alone, automated use is not recommended (especially in package maintenance scripts!). Furthermore, the output format of all commands is not specified and may change and will change as the underlying commands change. Apt-key attempts to detect such usage and, in these cases, generates alerts for standard error output.