From: Andrew Loewenstern <andrew_loewenstern@il.us.swissbank.com>
Date: Fri, 8 Sep 95 10:05:58 PDT
To: Hal <hfinney@shell.portal.com>
Subject: Re: GAK Hacks
Message-ID: <9509081705.AA03422@ch1d157nwk>
MIME-Version: 1.0
Content-Type: text/plain


Hal writes:
>  One would be to create a patcher which would let you change the
>  set of certificate authorities accepted by the browser.  Currently
>  the browser accepts at least one (an internal Netscape test CA)
>  which is not needed by end users.  Maybe its public key could be
>  statically overwritten by the patch program with the public key of
>  the replacement CA.  This sounds simple and safe.  The patch program
>  can confirm that the data being changed matches the test CA.

This is an excellent idea, assuming the new CA's key will fit in the same  
amount of space or less than the test CA.  How big is the test key?

Of course, Netscape could decide to remove the test CA certificate from  
future versions of the browser.  However, you could probably replace the  
Verisign certificate with your CA certificate and then have your CA sign the  
Verisign certificate so the browser can still use both.  :-)

>  This second patch is more advantageous for end users as it allows
>  them to have strong encryption rather than the weak 40 bits which
>  we have been breaking.  The first would be a more direct demonstration
>  of the difficulties of using certificate restrictions to limit
>  functionality.

I don't think this is necessary as domestic versions of Netscape have already  
been exported and are available on non-U.S. FTP sites...

>  The criteria.txt paper suggests checksumming the cryptographic
>  routines to prevent patches like this, but generally I think such
>  checksums can be defeated pretty easily.  I doubt that Netscape
>  currently has any such thing, though.

It only makes it harder to patch.  Anyone with a clue knows that there is no  
such software-only protection that can't be defeated.  Even hardware/software  
dongle type protection can be defeated by altering the software to not check.


andrew