[cryptography] What is the state of patents on elliptic curve cryptography?

D. J. Bernstein djb at cr.yp.to
Sun Aug 25 17:55:43 EDT 2013

Zooko Wilcox-OHearn writes (on the old cryptography at metzdowd.com list):
> I'd be keen to see a list of potentially-relevant patents which have
> expired or are due to expire within the next 5 years.

http://ed25519.cr.yp.to/software.html includes a chart and pointers.
Pretty much the entirety of the ECC patent FUD comes from patents that

   * have expired by now (Schnorr in 2008, Crandall in 2011, etc.) and
   * never claimed in the first place to cover anything that we're
     actually doing in real-world ECC.

The only exception I'm aware of is the point-compression patent 6141420,
but there's very solid prior art for that one, and in any case it'll
expire in July 2014.

---D. J. Bernstein
   Research Professor, Computer Science, University of Illinois at Chicago

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