Using PuTTY and PuTTY Private Keys for server login are considered to be most secured way to log in to servers. They are but only to the extent of data transaction between your system and the cloud server.
But within your organization, if a unauthorized person gets hold of the PuTTY Private Key (.ppk) file he can misuse the same making the entire system more vulnerable.
Clouds like Amazon AWS, GitHUB, IBM allows PuTTY and ppk file to log in.
TSafe2 file Protection for PuTTY is designed especially to prevent unauthorized use of PuTTY private key files (.ppk files).
Here is a brief guide on how to use TSafe2 Putty file Protection Tool.