>Yes Mr Guy Barrete,
>
>Physically in the database (.mdb) the data should be encrypted?
>How much volume of data access can handle to get good performance?
>How much access is reliable?(like corruption of database)
>
>please help me

Well if you want to encryp data itself, you can come up with your own encryption method and store the encrypted data in the database. You can use Microsoft Crypto API if you want more robust encryption.

>How much volume?
I depends.
10 users with a lot of transactions. 25 with less transactions.

>reliable?
That's a problem.
You have to come up with a maintenance plan to do a Compact each day. It should solve the corruction problem that appears from time to time in a multi-user environement with Access files.