If you've been sent a file containing the RADIUS server information then you'll need to uncompress, decrypt and untar the file to access the contents (a number of files equal to the number of your RADIUS servers):
Open a Finder Window and find the provided .tar.gpg.zip file.
Double click on it to unzip it. A .tar.gpg file is generated.
Double click on the .tar.gpg file and you should be prompted for a password. Enter the supplied password. A .tar file should generated.
Double click on the .tar file and a directory should be generated.
Double click on the directory to show the files.
gpg <filename.tar.gpg> > <filename.tar> (prompts for password)
tar xvf <filename.tar>
doctor@jadzia/tmp What? unzip holby.nhs.uk.tar.gpg.zip
doctor@jadzia/tmp What? gpg holby.nhs.uk.tar.gpg
gpg: AES256 encrypted data
gpg: encrypted with 1 passphrase
doctor@jadzia/tmp What? tar xvf holby.nhs.uk.tar
Install Kgpg, igoring the key generation.
Click on the .tar.gpg.zip file in a file browser. Ark should open with the .tar.gpg in it.
Click 'Extract' and save the file out.
File the new .tar.gpg file in a file browser and click on it.
You should be prompted for the passphrase. Enter it.
A new .tar file should be saved next to the .tar.gpg file.
Click on the .tar file and the contents should open in Ark.