Oct 05, 2007 Generating Keys. Generating public keys for authentication is the basic and most often used feature of ssh-keygen. Ssh-keygen can generate both RSA and DSA keys. RSA keys have a minimum key length of 768 bits and the default length is 2048. When generating new RSA keys you should use at least 2048 bits of key length unless you really have a good reason for using a shorter and less secure.
One effective way of securing SSH access to your cloud server is to usea public-private key pair. This means that a public key is placed onthe server and a private key is placed on your local workstation.Using a key pair makes it impossible for someone to log in by using justa password, as long as you set up SSH to deny password-basedauthentication.
This article provides steps for generating RSA keys by using PuTTYgen onWindows for secure SSH authentication with OpenSSH.
In Windows, use PuTTYgen to generate your public and private keys.
You can use the RSA key pair in the following ways.
When you create a cloud server, you can assign a public key from the list of keys.If your key is not already in the list, you may add it, and then assign it.
Add a new public key to the list
Assign a public key
To make use of your newly generated RSA key pair, you must tell PuTTY touse it when connecting to your cloud server.
To edit the file (or create it), run the following command on the cloud server:
Paste the text onto its own line in the file.
You must have the key available in your clipboard to paste it. The key and itsassociated text (the ssh-rsa identified at the start and the comment at the end)must be on one line in the file. If the text is word-wrapped onto multiple linesan error might occur when connecting.
If you created the authorized_keys file, change its permissionsafter you’re done editing it by running the following command:
Open PuTTY, and go to the SSH > Auth section.
Browse to the location of the key file, and load the private key.
Go to the Session page, and save the session. This saves the configurationso that PuTTY uses the key every time that you connect to your cloudserver.
After you save your session, your key is loaded automatically when youconnect to your server.
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