Generating a SSH key with PuTTY

PuTTY is a free implementation of SSH- and Telnet-services for Windows.

To be able to use an SSH Client you need first of all the program PuTTY and an public-/private key pair. To generate a new key pair, you need the program PuTTYgen, which is a part of the installation of PuTTY.

This is how you make an SSH key:

  • Download and install Putty from https://www.putty.org/ 
  • Start PuTTYgen. Choose RSA, type a bit size of 4096 and press the Generate Button.
  • After you pressed the Button, the program tells you to move your mouse. Based on your movements the program generates an SSH key.
  • After the process, you should use your username as your key comment.
  • As your key passphrase, you should choose a fitting password.

Register your SSH key

How to register your Public key:

  • Copy the Public key from the text field and write it on your target machine in the file authorized_keys.
  • We also need the public-key to allow access from outside via gateway.kph.uni-mainz.de.

How to register your Private key (OS specific):

Windows:

  • Below the Button Generate some new buttons enabled. Click on Save private key.
  • Start PuTTY then go to the menu Connection > SSH > Auth. Press the Browse... Button and select your private key. The Key will now be used in your next Session.
  • Go to Sessions and write your target Host name or IP-Adress, give your Session a suitable name and click Save. Now you can double click your Session and your private key will be automatically loaded.

Linux/Mac:

  • In the menu Conversions > Export OpenSSH Key in PuTTYgen, you can save the private key into the OpenSSH format, which is needed.
  • Name your key "id_rsa" and copy it in your Linux system.
  • Safe the file into the directory.ssh/.
  • With the command sudo chmod ~/.ssh/id_rsa you can reset the permissions for your key. This step is needed because the key is still unprotected and the system will most likely ignore your key.