1.   run   ssh-keygen -t ecdsa -b 256 -C none -f authorized_keys

• "-t" determines the type of cipher to use

• "-b" is how many bytes

• "C" is the comment to place at end of key

• "-f" is the name of the private key file.  The public key will end with .pub

  2.  move the file that doesn't end in ".pub" from server

• Preferably onto machine that has PuTTY

• This is the private key used to access server

  3.  rename the .pub file to authorized_keys or whatever needed for sshd

• the contents can also be appended to existing file

• ensure home folder doesn't have "o-" or "g-" write permission

• file should only have "u+rw" permission

  3.  convert private key (.pem) into ".ppk" for use in PuTTY

• Open PuTTY Key Generator

• "Load" the .pem file

• Window should open explaining it's incompatibility and suggest selecting "Save Private Key"

View contents of file with:

ssh-keygen -l -f file_name