Case study - Patent invalidation - Finding hidden prior art for billion dollar patent suit against Apple using no-cost trial version of Ambercite

Technology investor VirnetX has recently convinced a jury in Texas to award US$502 million in patent infringement damages relating to secure communication in its FaceTime, iMessage, and VPN On Demand services. VirnetX is now seeking to have these damages raised up to one billion dollars.

Ambercite has been following this case with interest for many years. More recently, it has released a trial version of its innovative Ambercite patent searching tool. While lacking in some features compared to the professional version, we were curious to ask - just what could the trial version tell us about prior art for the patents at suit in this case?

We will investigate this below - and also provide some details about the additional knowledge provided by the paid version. Firstly though, lets focus on what any one can find after registering for the trial version.

What hidden prior can the no-cost trial version of Ambercite find?

Arstechnica has reported that their are 4 patents in suit:

  • US6502135Agile network protocol for secure communications with assured system availability
  • US7418504, Agile network protocol for secure communications using secure domain names
  • US7490151Establishment of a secure communication link based on a domain name service (DNS) request
  • US7921211,  Agile network protocol for secure communications using secure domain names

These patents are found in two patent families, both with priority dates of 30 October 1998, with the first listed granted family members for these patent families being the first two patents on this list.  Both of these first patent claim a method of creating a virtual private network.


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Ambercite applies innovative AI algorithms to a database of 106 million patents and 156 million patent citations to determine the most similar patents to one or more starting patents. The simplest possible query using the trial software would look like this:












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However, even within the trial version, we can go beyond this. We could, for example. request a patent validity search, in this case for patent families first published before the priority of date of October 1998. The requesting query would like this - the changes over the default settings are circled below. 










The top six patents found by this search are shown below, and if you double click on this, you can gain the see the full list of patents returned by this query. Note too that we have highlighted all references to the term secure, as this is an important part of the claimed technology. 

Of these top six patents, three are hidden in this trial version  - but only a further two patents are hidden of the remaining 19 patents.


"Known" vs "unknown" patents

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An important part of the Ambercite Algorithm is the ability to find what we define as 'unknown' patents, which are patents families that have not been previously cited against the patents being analysed. The full list of 25 patents contains both known and unknown patents - but it is possible to apply a filter to only show the unknown patents, as shown in the box to the right:








If we do this, we will see that six of these patents are unknown, including US5864683. This is shown below in the patent review mode available in Ambercite, and selected by clicking on the image or abstract for any patent found.

US5864683 patent found.gif

What if you were to run a search in the paid version?

This would produce a much longer list of similar patents, 360 in total, of which 317 would be similar but not previously cited patents. 59 of these unknown patents have references to secure or security in their title or abstract, 190 refer to networks, while 23 of these unknown patents refer to both. Many of the unknown patents are quite relevant to the technology in questions, with just one example being US5684951Method and system for user authorization over a multi-user computer system.


Are any of these patents filed by Apple?


Apple licensing query

None of the prior art patents in either of the trial or paid list of results are filed by Apple.

It is also possible to run a similar query for similar patents filed after the priority date of the two Virnetx patent families - the resulting query looks like this:

Again this produces a list of 25 patents, all filed after October 1998. None of these 25 patents are filed by Apple.

We do get a different result if we run a search in the paid version, and search for a greater number of patents. This does return an Apple patent, being US7532862, for a Method and apparatus for configuring a wireless device through reverse advertising, priority date of 2002, which at one part discloses: 

In a variation on this embodiment, the new wireless device additionally receives an encryption key to facilitate secure communications across the existing wireless network. 

Disclosure of a similar concept in a later patent is not proof of infringement of course, but it does  provide an interesting perspective.


How to access the trial version

You can sign up to the no-cost trial version via the button found below. Some limitations apply, but even so you can run a functional search and see just what Ambercite is capable of.

Mike Lloyd