@dowsoninc
But have you connected the key with a droplet, when you create the droplet?
Try to login with PuTTY and the key, does that work?

@dowsoninc

The function name is actually ssh2_connect. In your code, you’re using ssh2connect – also ssh2_auth_pubkey_file instead of ssh2authpubkeyfile. It may be a formatting issue with your post, but just for clarity :-).

As for the connection, I’m using a slightly modified version of what you have right now and it works.

<?php
$host   = 'ip_or_hostname';
$port   = 22;
$user   = 'username';
$pass   = 'passphrase';
$pubkey = '/path/to/key.pub';
$prikey = '/path/to/privkey';

$conn   = ssh2_connect( $host, $port );
$auth   = ssh2_auth_pubkey_file( $conn, $user, $pubkey, $prikey, $pass );

if ( $auth )
{
    echo 'Public Key Authentication Successful.' . PHP_EOL;
}
else
{
    echo 'Public Key Authentication Failed.' . PHP_EOL;
}

In the code above:

$host should be the IP of the Droplet, or Hostname;

$port should be the port you connect to SSH on;

$user should be the username of the user you’re connecting as (i.e. root, for example);

$pubkey should be the path to the public key file;

$prikey should be the path to the private key file;

We initialize the connection by assigning the function call to $conn, then assign the authentication function call to $auth. This keeps the function calls out of the if/else statement and keeps things clean.

If $auth returns true (which it should only ever return true or false), we echo out that the connection was a success. If it returns false, we echo out that the connection was a failure.

If you’re not using a passphrase on your SSH Key Pair, you can remove $pass from line 5 and also from , $pass from line 10.

I would recommend using a passphrase for security, though removing those two instances would be how to handle authentication without a passphrase.

…

If that doesn’t work, then you need to check your keys. PuTTy uses and entirely different format for keys that isn’t compatible with standard SSH (OpenSSH), so trying to use keys that PuTTy creates won’t work unless you export them as OpenSSH keys specifically.