Import the public key used by the package management system.

From a terminal, install gnupg and curl if they are not already available:

sudo apt-get install gnupg curl

To import the MongoDB public GPG key, run the following command:

curl -fsSL https://www.mongodb.org/static/pgp/server-4.4.asc | \
sudo gpg -o /usr/share/keyrings/mongodb-server-4.4.gpg \ --dearmor