缺少X509客户端证书

我通过命令行中的curl(但在php中需要)得到了我想要的(令牌),方法是:

curl -d "client_id=theClient" -d "grant_type=password" "https://auth.theClient.de/auth/openid-co/token"

然后我尝试用php实现它:

<?php
$requestURL = 'https://auth.theClient.de/auth/openid-co/token';
$postData = "grant_type=password&client_id=theClient&scope=openid";
$headers[0] = 'Content-Type: application/x-www-form-urlencoded';
$ch = curl_init();
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_URL, $requestURL);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
$response = curl_exec($ch);
$responseArray = json_decode($response, TRUE);
var_export($responseArray);

应该给我令牌,但我收到了错误的请求和响应:

array (
   'error_description' => 'X509 client certificate is missing.',
   'error' => 'invalid_request',
)

我把证书导入Chrome Webbrowser(Stand & Gt;Advanced)。

我假设在apache webserver或php脚本(p12密钥库)中的配置中缺少证书。