(PHP 4 >= 4.0.6, PHP 5, PHP 7)
openssl_pkcs7_sign — Sign an S/MIME message
$flags= PKCS7_DETACHED [, string
openssl_pkcs7_sign() takes the contents of the file
infilename and signs them using the
certificate and its matching private key specified by
headers is an array of headers that
will be prepended to the data after it has been signed (see
openssl_pkcs7_encrypt() for more information about
the format of this parameter).
flags can be used to alter the output - see PKCS7 constants.
extracerts specifies the name of a file containing
a bunch of extra certificates to include in the signature which can for
example be used to help the recipient to verify the certificate that you used.
TRUE on success or
FALSE on failure.
Example #1 openssl_pkcs7_sign() example
// the message you want to sign so that recipient can be sure it was you that
// sent it
$data = <<<EOD
You have my authorization to spend $10,000 on dinner expenses.
// save message to file
$fp = fopen("msg.txt", "w");
// encrypt it
if (openssl_pkcs7_sign("msg.txt", "signed.txt", "mycert.pem",
array("To" => "email@example.com", // keyed syntax
"From: HQ <firstname.lastname@example.org>", // indexed syntax
"Subject" => "Eyes only")
// message signed - send it!
exec(ini_get("sendmail_path") . " < signed.txt");