I have this error
SSL peer had some unspecified issue with the certificate it received.
I'm use centos, NSS library.
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($fields));
curl_setopt($ch, CURLOPT_POST,1);
curl_setopt($ch, CURLOPT_VERBOSE, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSLVERSION, 4);
curl_setopt($ch, CURLOPT_SSLCERT, <cert_path>);
curl_setopt($ch, CURLOPT_SSLKEY, <key_path>);
curl_setopt($ch, CURLOPT_SSLKEYPASSWD, 'password');
curl_setopt($ch, CURLOPT_URL, $this ->url_merchant);