如何以安全的方式处理Web应用程序中的ftp密码

I'm working on a script (PHP+MySQL) that will let you edit file over FTP. What I'm trying to do is when user is logged in and connects to the server I want to memorize ftp password so it can be reused to reconnect to the server transparently (for example when browsing files). I don't want to store raw password in database for security reasons. I was thinking about storing password in a cookie with reference to the connection id in the database. But this doesn't sound secure enough either. How about storing temporary password entry in a database?I'm working on a script (PHP+MySQL) that will l