What is an SSH key pair?

By Joe Gardiner Tuesday, 23rd March 2010

An SSH key pair is the authentication used to create a secure channel for the SSH network protocol.

SSH is used to secure exchange data across a network, and is commonly used to issue commands to Linux based servers. You have SSH access to your vCluster, which allows you to carry out administrative tasks such as creating cron jobs.

To make an SSH connection secure public-key cryptography is used. In it simplest form this is a method for turning a message into an encrypted form that is only decrypted by the intended recipient.

For this encryption to work a Public and Private key are needed. The public key is used to transform the message into an encrypted for, and the public is required to then decrypt the message so it can be understood.

The user who expects to receive a message first must create a public and private key, and publish their public key. The person then sending the message takes this publicised key to encrypt the message at their location. This message is then sent to the original recipient who uses the private key to decrypt the message.

The sender can easily encrypt as many messages as they like using the published public key, however the private key is extremely difficult to work out based on their access to the public key.

When communicating with servers, your public key is saved on the server so that it can decrypt any incoming message or commands from your computer. The private key is saved on your computer so any communication using the SSH protocol, such as issuing terminal commands, can be decrypted successfully.

We have two guides for creating your own SSH key pair: Generating an SSH Key: Windows, and Generating an SSH Key: Mac OSX.

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