Re: subtext search in encrypted text
From: Ernst Lippe (ernstl-at-planet-dot-nl_at_ignore.this)
Date: 05/26/04
- Next message: Guy Macon: "Re: Working on ARC4-16 bit"
- Previous message: David Wagner: "Re: subtext search in encrypted text"
- In reply to: Orjan Austvold: "Re: subtext search in encrypted text"
- Next in thread: David Wagner: "Re: subtext search in encrypted text"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
Date: Wed, 26 May 2004 10:29:44 +0200
On Wed, 26 May 2004 09:15:52 +0200, Orjan Austvold wrote:
> I haven't actually tried to describe threats to the system in so many
> words, and I probably should have done so before posting to this list.
>
> Anyhow, here is a short list of the main parameters describing the
> system and its configuration:
>
> * clients to the system are software on cellular phones (but could of
> course be an intruders software),
>
> * clients communicate with the system on a protocol carried on either
> HTTP or HTTPS (WSP if on the mobile network),
>
> * clients are authorized either by plaintext username/password, by
> challenge-response (md4/5/6,SHA), or by the mobile network),
>
> * clients access the system by communication with a application server
> through a firewall
>
> * only the business software on the application server have access to
> the database (keys are stored on the application servers business logic
> (obfuscated?)),
Ok, it looks like the major weak point in your system are the
clients. Of course, you should also secure the servers but that
seems all very standard.
The main problem seems to be: how you can authenticate legitimate
clients. A few ideas:
* All cellular phones have a SIM that can securely hold keys.
Is there any way that you could use them?
* The "obvious" solution in this case would be to use SSL with
both a client certificate and a server certificate. Does the
phone have enough processing power and memory to do this? Is
there any way that you could put the private keys plus the certificate
on the phone? How secure is the memory of the phone?
* The risk that a phone will be stolen is high. It seems wise
to use a separate password or PIN to protect your application
(in addition to other forms of authentication).
* Can you trust the information about the identity of the
caller that you receive from the phone company? AFAIK the normal
ANI number information is not reliable.
It is an interesting application, like I said it cannot be
very secure, but there are several things that you could do
to make life more difficult for attackers.
Ernst Lippe
- Next message: Guy Macon: "Re: Working on ARC4-16 bit"
- Previous message: David Wagner: "Re: subtext search in encrypted text"
- In reply to: Orjan Austvold: "Re: subtext search in encrypted text"
- Next in thread: David Wagner: "Re: subtext search in encrypted text"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
Relevant Pages
|
