[Hampshire] Graphical encrypted folder utility?

I'm looking for a GUI utility, usable by ordinary users, that can manage
an encrypted directory. Ideally I'd like:

- all files in directory [or "folder" as we should call it now] are
encrypted

- one password/passphrase makes all files readable (ie, decrypted)

- adding a new file to the directory automatically encrypts it

- it would be nice if the utility would remember the password for a set
time (eg, five minutes)

Can anyone provide pointers to applications that do something like this?

Thanks,
Keith