Is this repository still valid.
It is on the installation help for muTect.
sudo git clone git@github.com:broadgsa/gatk-protected.git
Cloning into 'gatk-protected'...
Warning: Permanently added the RSA host key for IP address '192.xx.xxx.xx0' to the list of known hosts.
Permission denied (publickey).
fatal: Could not read from remote repository.