Storing Encryption Keys

Apologies if this type of question has been answered before.

I am designing a website for which just 100 people will be registering and will only be up for a about 1 month and have been asked to collect sensitive data which requires some extra security (ie identification numbers). Which is the best type of encryption for this, I have thought to use the AES_encrypt function (I’m programming in PHP). The problem that I have is that I don’t know how to store the key. I gather that it’s not good practice to store this on the same servers where you are hosting the database (I am hosting on a 1and1 package).

Will a php compiler solve the problem?

Thanks in advance.

You need to store keys on a different machine? Try to send each key with e-mail to some “backup” address, or simply use free ftp

No and no. Never use Email or use FTP for anything sensitive or to be secured. That is a death wish.