# SSH Key Pair

An SSH (Secure Shell) key pair is used for identity authentication and encrypted communication, consisting of a public key and a private key. The public key can be used to encrypt messages that **only** the private key can decrypt. This property is employed as a way of authenticating using the key pair. Your SSH key pair contains several public keys that can be placed on your server to access it securely.

## Supported Formats <a href="#supported-formats" id="supported-formats"></a>

SSH keys are typically stored in the \~/.ssh/ directory.

<table><thead><tr><th width="196">Format</th><th width="265">Start With</th><th>Minimum Length</th></tr></thead><tbody><tr><td><strong>RSA</strong></td><td>ssh-rsa</td><td>2048 bits</td></tr><tr><td><strong>ED25519</strong></td><td>ssh-ed25519</td><td>256 bits</td></tr><tr><td><strong>ECDSA</strong></td><td>ecdsa-sha2-nistp</td><td>256 bits</td></tr></tbody></table>

{% hint style="info" %} <mark style="color:blue;">**Note**</mark>

* <mark style="color:blue;">Provide your public key. Be careful not to use your private key.</mark>
* <mark style="color:blue;">You're recommended to use</mark> <mark style="color:blue;"></mark><mark style="color:blue;">**RSA**</mark> <mark style="color:blue;"></mark><mark style="color:blue;">or</mark> <mark style="color:blue;"></mark><mark style="color:blue;">**ED25519**</mark> <mark style="color:blue;"></mark><mark style="color:blue;">keys, as they have good compatibility and security.</mark>
  {% endhint %}

## Example <a href="#example" id="example"></a>

Here we take RSA format as an example.

### Public key <a href="#public-key" id="public-key"></a>

```
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDx6VN...
```

### Private key <a href="#private-key" id="private-key"></a>

```
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-256-CBC,5764636E65726F726974686D616E6F6E
...
-----END RSA PRIVATE KEY-----
```

## Limit <a href="#limit" id="limit"></a>

You can add up to 5 public SSH keys to create an SSH key pair.