PhilipBrown\Signature\Request::sign PHP Method

    public function sign(Token $token, $prefix = self::PREFIX)
    {
        $auth = [$prefix . 'version' => self::VERSION, $prefix . 'key' => $token->key(), $prefix . 'timestamp' => $this->timestamp];
        $payload = $this->payload($auth, $this->params);
        $signature = $this->signature($payload, $this->method, $this->uri, $token->secret());
        $auth[$prefix . 'signature'] = $signature;
        return $auth;
    }

 /** @test */
 public function should_accept_custom_prefix()
 {
     $auth = $this->request->sign($this->token, 'x-');
     $this->assertEquals('5.1.2', $auth['x-version']);
     $this->assertEquals('abc123', $auth['x-key']);
     $this->assertEquals('1412506800', $auth['x-timestamp']);
     $this->assertRegExp('/[a-z0-9]{64}/', $auth['x-signature']);
 }