Is it possible to add an option into "openssl_pkcs7_verify" to save the store the certificate into a variable instead of into a file? 

I tried:
---------------------------------------
ob_start();
openssl_pkcs7_verify("/home/busia/mail_firmata_mittente_cambiato", PKCS7_DETACHED, "php://stdout");
$pem=ob_get_contents();
ob_end_clean();
---------------------------------------

But I receive this warning:
---------------------------------------
PHP Warning:  openssl_pkcs7_verify() [<a href='http://www
.php.net/function.openssl-pkcs7-verify'>function.openssl-pkcs7-verify</a>]: sign
ature OK, but cannot open php://stdout for writing in /home/busia/prova2.php on
line 5
---------------------------------------

Writing the file and the reding it seems a waste of resources.

Thanks
Andrea Busia