SSH keys are a means of authenticating a user to an SSH server without using a password. Each “key” is actually a key pair consisting of a public key and a private key. Keys are more secure than passwords because they are significantly more complex.
While a password of eight characters is 72 bits long, SSH keys are often 2048 bits or longer. This longer string has many more possible permutations and therefore takes much more time to crack with a brute force attack.
If you require SSH access for multiple users, the use of SSH keys instead of individual logins can bypass many of the headaches involved in user management without violating PCI DSS. See What are the advantages of using SSH keys to control access for multiple users? for details.
The process involves generating a pair of SSH key files containing a private key and a public key. The private key is known only to the user’s computer; the public key will be known to the server. Each key is useless without the other; therefore, only individuals with both the private and the public key can gain access to the server, and the private key is never revealed to the server.
Users should take special care to not lose the private key. A lost private key cannot be replicated; therefore, the user cannot access the server until an administrator generates a new key pair. If you lose access to your server due to a lost key, contact our Support Team for assistance.
test@demo:~$ ssh-keygen -t rsa -b 4096 Generating public/private rsa key pair. Enter file in which to save the key (/home/test/.ssh/id_rsa): Created directory '/home/test/.ssh'. Enter passphrase (empty for no passphrase):
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