Try to git clone with error permission denied
$ git clone git@github.com:x25/coinhive-stratum-mining-proxy.git
Cloning into 'coinhive-stratum-mining-proxy'...
Warning: Permanently added the RSA host key for IP address '192.30.253.112' to the list of known hosts.
Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.