At a high level the steps are
1. Create a RSA public/private key pair. I am using PuTTY generator but there are a lot of other tools out there which do the same.
2. Create a URL definition in PeopleSoft and associate the RSA keys with the same.
So lets look at creating the RSA key pair first.
Launch the PuTTY Key Generator and select SSH-2 RSA (default) and then click on the Generate button. Once complete the public key, key fingerprint and key comment values are displayed. Key comment can be updated to some other value or can be left as-is. Put in a key passphrase.
Save the keys by clicking on the "save public key" and "save private key" button respectively.
Use .pub extension for the public key and .ppk for the private key. Filename can be anything for your choice. So for this discussion we will call this putty-gen.pub and putty-gen.ppk.
The highlighted text in blue in the above picture is the public key in OpenSSH format so copy that and then paste it to a text file. We will name this file sftpuser. No extension just sftpuser. I will explain shortly the reason behind this naming convention.
Provide putty-gen.pub or sftpuser file to the vendor so that they can add it to their sftp server.
Once vendor sets an account for you they will provide the sftp address, port is generally 22 and an userid. This userid should match the filename, so we will consider that the userid created by the external vendor is called sftpuser. Hence the naming convention. When you send the public key to the vendor you wouldn't know the userid so at that point the file can be called anything, the filename is more critical to the PeopleSoft setup than the vendor's setup.
Via the PuTTY gen tool navigate to Conversions > export OpenSSH Key and export the private key to a text file. Name this file sftpuser.ppk
You can always go back in time load the privatekey "putty-gen.ppk" file in PuTTY Generator and update the private key password.
While the vendor is doing their setup and configuration we have following two options in PeopleSoft.
The first one and the preferred one is to import the keys in the Digital Certificates component as this options stores them in the database. The second option is to store the keys on the file server. We will discuss both the options here.
where N_VENDOR is the URL definition created above
&filename is the filename as it test.txt