On 06 Nov 2014, at 8:05 AM, Kaspar Brand <[email protected]> wrote:

>> Is there another way to do this?
> 
> "Manually" performing what certificateExactMatch is specifying, I would
> say - i.e., use the (SSL_CLIENT_M_SERIAL,SSL_CLIENT_I_DN) tuple as a
> unique identifier for a specific client certificate.

Imagine I trust two roots, A and X, where X has been compromised.

I authorize the certificate chain A->B->C to perform a specific action. What 
stops the root X from issuing an intermediate certificate with subject “B” and 
a leaf certificate with subject “C” to produce a chain that goes X->B->C, and 
the client provides both the intermediate cert B and leaf certificate C during 
the SSL handshake?

In other words, if I only consider the serial number and issuer during 
authorization, what stops a compromised-but-still-trusted CA from issuing an 
intermediate cert that replaces another trusted issuer?

Regards,
Graham
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