17 Dec
2003
17 Dec
'03
11:17 p.m.
Bill Stewart writes:
It's _not_ free after 1997! I thought of it last fall, was surprised I couldn't find it anywhere in the literature, given that it's pretty obvious, but eventually found that a guy from Siemens had patented it in Germany and then gotten a US patent in ~1994. Unfortunately, he phrased it in terms of "commutative hash functions", with g^X mod p as an example, so it's more general.
Given all the prior art, I have a solid suspicion that the patent wouldn't hold up. The existance of the publically published Diffie Hellman patent, for instance, makes it rather hard to patent the more general case. Perry