function signs($data,$pfxpath,$pfxpwd) {
      $certs = array();
     openssl_pkcs12_read(file_get_contents($pfxpath), $certs, $pfxpwd);   // 其中pfxpath为证书路径       password为你的证书密码
     if (!$certs) {
           return;
    }
    $signature = '';
    openssl_sign($data, $signature, $certs['pkey']);
   return base64_encode($signature);
}