Hi gangl:
I realize that the problem stated herein has been solved by others,
so I'm not claiming I've done anything new -- it's only new to me. It
was a learning experience for *me* and my solution may help others.
In any event, I've finished creating a method for establishing what I
think is secure communication between two servers. I've written two
scripts that run on different servers, which confirm communication
between them via hard-wired urls and creating/writing/reading a
url-confirmation file.
The purpose of this exercise was to simply to keep database-access
data (i.e., user_name, password, key to decryption) secret. However,
the secret could be anything you want to keep secret -- secret being
defined as no data residing on the server of concern while allowing
that server access to the data when needed and under authorization.
Here's what I've done -- I have two domains, namely webbytedd.com
(the Master) and php1.net (the Slave) -- both domains reside on
different servers. The domain names really don't matter, it's just
that this method currently works between those two domains.
Statement of Requirements:
1. The Master requires "access" to it's database.
2. The Slave keeps "access" to Master's database in it's own database.
3. It's required that "access" remain secret in the event that the
Master is hacked.
*The term "access" above is defined as database-access data, such as
user_name, password, and key to decryption.
Description of Method:
1. When the Master wants access to it's database, it first creates a
url-confirmation file and writes a token to that file, which resides
on the Master. I've used time() as the token, but the token could be
any variable -- it really doesn't make much difference other than the
value should be different each time.
2. The Master then sends a cURL request to the Slave via a POST where
the POST variable contains the token.
3. The Slave when receiving the POST request from Master reads the
token from the newly created url-confirmation file residing on the
Master and then compares that token with the token provided by the
POST -- if the tokens match, then the Slave returns "the access" to
the Master. If not, the process fails.
4. After receiving "access" the Master deletes the url-confirmation
file and continues with it operation. If the Master does not receive
"access" then it deletes the url-confirmation file and exits.
This method sounds simple enough and does several things.
1. There is no "access" stored on the Master.
2. While the Slave has "access" for the Master stored in its
database, the access to the Slave's database is kept in an
out-of-root (not open to the web) file. Note, in this case, this was
not possible on the Master because the host did not allow out-of-root
files -- but that is only tangential to the problem addressed here.
3. If a hacker did obtain access to the Slave database, then the
hacker would discover the contents have been encrypted and only the
Master has the decryption key kept in it's database.
4. If a hacker did obtain access to the code residing on the Master,
then the hacker could not access the Master's database because the
"access" data is recorded on another server (i.e., Slave).
Furthermore, the hacker could not get the code to run anywhere else
because the Slave's "look-up URL" for the url-confirmation file is
hardwired to the Master address.
5. And lastly, all communication between both domains is done via https.
Now, for the exception of both server's being hacked at the same
time, what could go wrong?
Cheers,
tedd
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