These three statements are *most* interesting. The Diffie-Hellman patent (4,200,770) itself references the Information Theory and AFIPS papers and their publication dates. And as stated, the patent filing date was Sept 6, 1977. Clearly anything in the AFIPS paper is fair game since it appeared more than a year before filing. But for the IT paper, I don't know whether the clock starts when the paper is submitted or when it is actually published; that would make a difference here. Anybody know? --Phil ------- 36. The idea of public key cryptography and digital signatures is disclosed in a paper titled "Multiuser cryptographic techniques" by Whitfield Diffie and Martin E Hellman, National Computer Conference, vol. 45, 1976. The paper was presented at a public conference in mid-June 1976, and published as part of the conference proceedings shortly thereafter. This was more than one year before any patents were filed, and therefore in the public domain according to 35 USC 102(b). A copy of the paper is attached as Exhibit T. 37. Another paper by Diffie and Hellman, "New Directions in Cryptography", IEEE Transactions on Information Theory, vol. IT-22, no. 6, Nov. 1976, was submitted on June 3, 1976. It discloses the public key distribution system of the DiffieHellman patent. A copy of the paper is attached as Exhibit U. 38. A survey paper, "The First Ten Years of Public-Key Cryptography", was published by Diffie in Proceedings of the IEEE, vol. 76, no. 5, May 1988. A copy of the paper is attached as Exhibit V. It states on p. 563 that Exhibit U was publicly distributed in June 1976 and publicly disclosed at the National Computer Conference, also in June 1976. The Diffie-Hellman patent was filed on Sept. 6, 1977. This was more than one year later, and hence the patent is invalid and unenforceable according to 35 USC 102(b).