TQP are currently suing more large companies for using RC4 and SSL/TLS, but the way the patent was awarded confuses me.
From the Cipherlawgroup article linked to:
The application for the ’730 patent was filed on April 23, 1992, and claimed priority as a continuation-in-part to an earlier application filed on Oct. 6, 1989. The ’730 patent was originally issued with only two claims:
- A method for transmitting data comprising a sequence of blocks in encrypted form over a communication link from a transmitter to a receiver
- The method as set forth in claim 1 further including the step of altering said predetermined number of blocks each time said new key value in said first and said second sequences is produced.
Now, since that 1989 wording, TQP have been allowed to add features to the patent and expand it through continuation and the 1992 additions appear to be the core of the lawsuit.
So if one was searching for prior art, would it need to be found before 1989 or 1992? What is the date of validity of this patent?