While a password can be cracked with a brute force attack, SSH keys are almost impossible to decipher by brute force alone. When generating a key pair, two long character strings are created. These are called the public key and the private key. You can place the public key on any server and then connect to this server with a client on which the private key is stored. If the two match, the system unlocks without the need to enter a password.

To increase security even further, the private key can be provided with a password. This must be entered once before a connection is established.