# of

Learn how to create an API key from an identifier and a private key.

This method creates an API key from a UUID identifier and an optional private key.

## Signature

This method has the following signature:

```php
public static function of(string $identifier, ?string $privateKey = null): self
```

This method returns a new instance built from the given identifier and private key.

## Example

Here is a basic example of how to use this method:

```php
<?php
use Croct\Plug\ApiKey;

$apiKey = ApiKey::of('f47ac10b-58cc-4372-a567-0e02b2c3d479');
```

## Parameters

The following list describes the supported parameters:

- `identifier`: `string`

  The public identifier of the key, as a UUID.

- `privateKey`: `string|null` (optional) (default: null)

  The private key used to sign user tokens. When omitted, the key cannot sign tokens.