Index: wp-pass.php
===================================================================
--- wp-pass.php	(revision 17420)
+++ wp-pass.php	(working copy)
@@ -11,9 +11,11 @@
 
 if ( get_magic_quotes_gpc() )
 	$_POST['post_password'] = stripslashes($_POST['post_password']);
+	
+$postid = (int) $_POST['post_ID'];
 
 // 10 days
-setcookie('wp-postpass_' . COOKIEHASH, $_POST['post_password'], time() + 864000, COOKIEPATH);
+setcookie("wp-postpass_{$postid}_" . COOKIEHASH, $_POST['post_password'], time() + 864000, COOKIEPATH);
 
 wp_safe_redirect(wp_get_referer());
 exit;
Index: wp-includes/post-template.php
===================================================================
--- wp-includes/post-template.php	(revision 17420)
+++ wp-includes/post-template.php	(working copy)
@@ -554,10 +554,10 @@
 	if ( empty($post->post_password) )
 		return false;
 
-	if ( !isset($_COOKIE['wp-postpass_' . COOKIEHASH]) )
+	if ( !isset($_COOKIE["wp-postpass_{$post->ID}_" . COOKIEHASH]) )
 		return true;
 
-	if ( $_COOKIE['wp-postpass_' . COOKIEHASH] != $post->post_password )
+	if ( $_COOKIE["wp-postpass_{$post->ID}_" . COOKIEHASH] != $post->post_password )
 		return true;
 
 	return false;
@@ -1204,16 +1204,18 @@
  * @since 1.0.0
  * @uses apply_filters() Calls 'the_password_form' filter on output.
  *
+ * @param int|object $post An optional post.  Global $post used if not provided.
  * @return string HTML content for password form for password protected post.
  */
-function get_the_password_form() {
-	global $post;
-	$label = 'pwbox-'.(empty($post->ID) ? rand() : $post->ID);
-	$output = '<form action="' . get_option('siteurl') . '/wp-pass.php" method="post">
-	<p>' . __("This post is password protected. To view it please enter your password below:") . '</p>
-	<p><label for="' . $label . '">' . __("Password:") . ' <input name="post_password" id="' . $label . '" type="password" size="20" /></label> <input type="submit" name="Submit" value="' . esc_attr__("Submit") . '" /></p>
-	</form>
-	';
+function get_the_password_form( $post = null ) {
+	$post = get_post( $post );
+
+	$label = 'pwbox-' . $post->ID;
+	$output = '<form action="' . get_option('siteurl') . '/wp-pass.php" method="post">';
+	$output .= 	'<p>' . __('This post is password protected. To view it please enter your password below:') . '</p>';
+	$output .= "<p><label for='$label'>" . __('Password:') . " <input name='post_password' id='$label' type='password' size='20' /></label> <input type='hidden' name='post_ID' value='$post->ID' /> <input type='submit' name='Submit' value='" . esc_attr__('Submit') . "' /></p>";
+	$output .= '</form>';
+	
 	return apply_filters('the_password_form', $output);
 }