openssl_spki_export_challenge

(PHP 5 >= 5.6.0, PHP 7)

Exports the challenge assoicated with a signed public key and challenge

string openssl_spki_export_challenge ( string &$spkac )

Exports challenge from encoded signed public key and challenge

Parameters:

spkac

Expects a valid signed public key and challenge

Returns:

Returns the associated challenge string or NULL on failure.

Exception:

Emits an E_WARNING level error if an invalid argument is passed via the spkac parameter.

Examples:

openssl_spki_export_challenge() example

Extracts the associated challenge string or NULL on failure.

<?php
$pkey = openssl_pkey_new('secret password');
$spkac = openssl_spki_new($pkey, 'challenge string');
$challenge = openssl_spki_export_challenge(preg_replace('/SPKAC=/', '', $spkac));
?>

openssl_spki_export_challenge() example from <keygen>

Extracts the associated challenge string issued from the <keygen> element

<?php
$challenge = openssl_spki_export_challenge(preg_replace('/SPKAC=/', '', $_POST['spkac']));
?>
<keygen name="spkac" challenge="challenge string" keytype="RSA">