In reference to the patent: US20140359280

There is prior art that has been published by myself and colleagues in

D. W. Chadwick, A. Basden. “Evaluating Trust in a Public Key Certification Authority”, Computers and Security, Vol 20, No 7, (Nov 2001) pp 592-611.


E.Ball, D.W Chadwick, A. Basden. “The Implementation of a System for Evaluating Trust in a PKI Environment” in Trust in the Network Economy, Evolaris vol 2. Eds Otto Petrovic, Michael Ksela, Markus Fallenbock, Christian Kitti. Pp 263-279, SpringerWein, 2003. ISBN 3-211-06853-8. Available from http://www.cs.kent.ac.uk/pubs/2003/2126/index.html

My question is, does this work invalidate any of this patent? Does it invalidate any similar patents?

  • 1
    I am not sure we can answer such type of question its out of scope of 'Ask Patents' but just to provide and index prior art you know for subject patent I am not flagging it for technology and production.
    – Pushpak
    May 26, 2015 at 6:02

1 Answer 1


I think there are some gaps between what is shown in your publication and the application's Claim 1, though your publication is clearly not without some relevance to the field of the invention.

Other prior art may be needed to fill this gap if you have the time or inclination to find it.

In Claim 1, what seems like the crux of the method is "for respective certificates issued by the certificating authority, determine a certificate trust level; and according to the certificate trust levels of the certificates issued by the certificating authority, determine a certificating authority trust level of the certificating authority".

Thus, the invention first assigns trust scores to individual issued certificates, and then to the CA based on a calculation on these individual trust scores.

Here's the part of the patent specification that discusses why it might make sense to do so:

As a fourth such example, some types of exploits may be detectable only by a collective evaluation of many certificates; e.g., the issuance of certificates on behalf of a particular domain concurrently by two or more different certificating authorities 108 may raise a security concern, but the detection of this condition may be difficult to discern from the examination of any particular certificate 106 in isolation.

Your publication on the other hand does not seem to take individual issued certificates into account at all.

Myself, I am not able to see why the existence of multiple certificates for a domain should reflect poorly on the trustworthiness of the CAs issuing those certificates (assuming they were issued to the same entity).

In any case, having skimmed the abstract of your publication, it seems to me that it does not disclose the crux of the claimed method.

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