I was wondering if it is possible to create a secure database system
using RDBMS(MySQL, Oracle, SQL*Server, PostgreSQL etc) and web
scripting/programming language(Perl, PHP, Ruby, Java, ASP, etc) combination?

I have the following in mind:

I wanted to store all my( and my brothers and sisters) important
document
information such as birth certificate, SSN, passport number, travel
documents, insurance(car, home, etc) document, and other important
documents
imagined in the database.

The data will be entered either manually and/or scanned(with OCR). I
need to
be able to search on all the fields in the database.

We have 10 computers(5bros, 4sisters, and myself) plus 1 server with I
maintained. The data should be synchronize/replicate between those
computers.

Well, so far it is easy, isn't it?

Here's my question:

a) How can I make sure that it secure so only authorized person can
modify/add/delete the information? Beside transaction logs, are there
any
other method to trace any transaction(kind of paper trail)?

Assuming there are 3 step process to one enter the info e.g:
- One who enter the info (me)
- One who verify the info(the owner of info)
- One who verify and then commit the change!
How can I implement such a process in RDBMS and/or PHP or any  other web
language?

b) How can I make sure that no one can tap the info while we are
entering
the data in the computer? (our family are scattered within US and
Canada)

c) Is it possible to securely synchronize/replicate between our
computers
using VPN? Does RDBMS has this functionality by default?

d) Other secure method that I have not yet mentioned.

Anyone has good ideas on how to implement such a systems?

Thanks