Private/Public Key Authentication

Creating a Private/Public Key Pair

If you have never use public key authentication before, you will have to start by creating a key pair. Once the key pair is created, you need to keep the private key in a safe location. Never upload the private key, and never send it by Email. Whoever has your private key can use it to try logging in to ARROW. So, treat the private key as a secret at all times.

The easiest way to prepare a key pair is the use of "puttygen", part of the "putty" software on Windows. Pressing the Windows Key together with R will open a window where you enter "puttygen". Once you press "Ok", the software opens up:

We can go with the defaults and just click on the "Generate" button. Some randomness depends on you moving the mouse around on the screen. Once enough random data is gathered, the private and public key will be generated.

Once the keys have been generated, you need to store the private key in a easy to find location on your local file system. I recommend creating a folder "Keys" within your "Documents" folder, but any other location is fine as well. The idea is that you may easily forget where the key is stored when you need it a later point in time.

Click on "Save private key", which will create the following dialog box for you:

In an ideal world, assigning a password for your private key would be best, but that also means that you may have to enter that password every time you use the key, which can be a problem. Not assigning a password is one more reason to never risk losing this private key file.

Navigate to the "Keys" folder in the "Documents: folder, and give the key a meaningful name. Something that tells you what it is used for, like "arrow-private". The extension ppk is automatically added when the key is saved.

Regarding the public key: It is not necessary to save the public key. When loading a private key, the public key is automatically displayed again at the top of the "puttygen" window. It looks somewhat like this:

ssh-rsa AAAAB3NzaC1yc2EAfAADAQABAAABAQDOHgbwUYAAo+BMpvskvLw6eTqqs8OVUMSbAIobbC2/518PpJ/b
jW0n9NM4jlNJlEpuT79ZSv5RwSW8rP82qtcLdSEisxhXkyRLLjbzRWQSGxlVUI+K6MfZeFRYD+nqEH4Q1nSvxWJM
FigswLuWsygcJnGxv0FBGBP7pUrK5pz6AEv5Blf0MCuy0bvuIGhOYEMO4JeId6WYrAwJmZ3mjHqVwO3uQtrYP1Gi
71A+yk4x2hZepwW5fHiTbeCU/kDycqWPsXOI3e+eBIDBHmaaD7uOkIWT/GnSBTvYr4NkF2xVxnmCsQ5eks13QdY6
MX1/gjwLl3nOPl6HBLc+KiHPLlMB rsa-key-20260325