Page password protect – changing log in time

Hi there,

I have a number of pages on my website which I have password protected. Unfortunately the cookie sets the time to stay logged in at 10 days. I want to reduce this to 20 minutes. I have read around and found a lot of references to older methods, but as I’m running 3.5.1 its a bit different and i’m not sure what to change.

What I have found is this, but what do I alter?

// 10 days
	setcookie( 'wp-postpass_' . COOKIEHASH, $wp_hasher->HashPassword( stripslashes( $_POST['post_password'] ) ), time() + 10 * DAY_IN_SECONDS, COOKIEPATH );

Please help, thanks.