When you would like putty to autologin to the HPC servers without asking for username and password every time you connect.

Step-by-step guide

Creating the Public/Private Key Pairs

1. Open puttygen.exe
2. Click Key → Parameters for Saving File
   
   1. Set PPK file Version: 2
      
   2. Click OK
3. Click Generate
   1. Create some chaos (i.e. jiggle the mouse)
4. Click Save private key
   1. Click yes to save it without a passphrase to protect it 
   2. Save it somewhere on a secure location (not "publicly" accessible)
5. Copy all the text within the "Public key for pasting into OpenSSH authorized_keys file:" box

   
   

   Make sure you copy all the text as there usually is a scrollbar within the box. Your ending text should usually include "rsa-key-" or similar.

6. Open up a putty terminal
   1. Connect to HPC of choice 
   2. navigate to ~/.ssh
   3. Add what you copied (your public key) to a new line in "authorized_keys" file
      1. You can use VIM, nano, or other

Setting Up Putty

1. Open Putty (https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html)
2. Connection→SSH→Auth
   1. Under "Private key file for authentication" click Browse
   2. Navigate to your private key file that you saved in step 4 
   3. Click open
      
3. Go back to session
   1. In "Host Name (or IP address)" put in: username@quantum-login1-ema
      1. Port: 22
4. Don't forget to save your session so you don't have to repeat these steps
   1. Under "Saved Sessions" box enter a session name (e.g. EMA)
   2. Click Save
      

Related articles

https://groups.google.com/a/solvay.com/g/sbs-quantum-hpc/c/7LqS_iGvRz8?hl=fr