A Secure Shell key — usually called SSH key — allows you to create a secure connexion on a network that is not secure, such as the Internet.

The use of SSH keys is of great importance in terms of Web security, as they allow commands to be launched on a server in a secure manner.

An SSH key has two components:

  • A public key that is available for all (the client and the server). It is a cryptographic key that can be obtained and used by anyone to encrypt messages intended for a particular recipient. The server uses it for authentication.
  • A private key (kept secret). It is known only by the client and is kept on  their machine. The private key is used for deciphering messages with the corresponding public key.

Using an SSH key to create a connection between two computers offers the advantage that only the public key needs to be exchanged on the network. Since transmissions encrypted with a public key can only be deciphered with the corresponding private key and a password, a pirate cannot do anything to decipher communications on the Web, as they have no access to the private key.