It's specific to ECDSA recovery, where instead of using a pubkey and message to validate a signature you use a signature and message to recover the pubkey, so the age of ECDSA isn't particularly relevant in and of itself.

Huh, interesting! I somehow assumed that that fact would be obvious enough to implementers for there to be prior art. Do you have any more details?

> obvious enough to implementers for there to be prior art. Do you have any more details?

I haven't made any comment in this thread on its validity. :)

US8788 827B2