Replacing apt-key on Ubuntu CRAN

If you have used apt-key on Ubuntu (or Debian) recently, you may mave noticed a message along the lines of Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)). The final Ubuntu release with apt-key will be Ubuntu 22.04.

As the warning suggests, keyring files should be located in the /etc/apt/trusted.gpg.d/ directory. The first step is to download my .asc key file, which is an armored, ASCII version of my public key file.

wget https://cloud.r-project.org/bin/linux/ubuntu/marutter_pubkey.asc

It should be noted that the .asc public key file is no longer stored on a keyserver, but in the Ubuntu directory on CRAN. To verify that this is indeed my public key file, run

gpg --show-keys ./marutter_pubkey.asc   

The resulting output should contain my fingerprint E298A3A825C0D65DFD57CBB651716619E084DAB9 with an expiration date of 2027-09-30.

Once you have verified the key, you can copy the .asc file to /etc/apt/trusted.gpg.d/. It is also possible to download the file and copy it to the proper directory with the following command:

wget -qO- https://cloud.r-project.org/bin/linux/ubuntu/marutter_pubkey.asc | sudo tee -a /etc/apt/trusted.gpg.d/cran_ubuntu_key.asc

This information has been added to the readme files on the CRAN Ubuntu site.