WebApp Sec: Re: How to perform SSL certificate validation ?

[Ron <ron () gwn ca>]

Hello,

Nagareshwar Talekar wrote:
>  I don't know how to perform the check for 3rd step. How can we ensure
>  that CA is trusted? One of my colleague told that I have to store all
> trusted
>  root certificates and then compare incoming certificate with existing
> ones..
>
>  Is there any better way to check this ...?
As far as I know, that's the only way it's done.  If you check the
settings of any web browser, it stores a list of trusted CA's.  You can
probably use one of those lists.

>  Also I was told that certificate validation is done to prevent the
> SSL-MITM attack
>  Is this the only reason or is there any other reason for which the
> SSL certificate
>  validation is done ?
As far as I know, that's the only reason.  If some malicious individual
(like Cathy) manages to get between your client and server, Cathy can
send the client her certificate and the client will happily encrypt the
data destined to Cathy, thus giving Cathy all your data.

If you check the certificate against a trusted CA, it'll tell you that
the certificate you were given isn't actually the intended server's, and
you know that an attack is going on.  For a trusted SSL system, that is
a very important step to take.

> It will be great if you can throw some light in this matter. Any
> links to relevant
> websites will do as well.
>
> Thanks
I don't have any links, but Googling "SSL MITM" should pull up something
useful.


Hope that helps,

Ron

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