With regards to the IPR disclosure available at https://datatracker.ietf.org/public/ipr_detail_show.cgi?ipr_id=1036, the authors of that draft believe that there is no claims to do with regards to the patent; each of these two documents describes its own way to negotiate the identity protection during the TLS negotiation (the draft enables that by defining a set of specific TLS Cipher Suites, whereas the patent proposes specifying a new TLS extension for that purpose).
Computing a key from the premaster secret and the random values using the PRF function isn't patentable, since this is specified by TLS and SSL documents. From the authors' point of view, the way for the client and the server to negotiate the identity protection feature is the only part to be patentable. This is why the authors estimated that no IPR disclosure is required. On the other hand, the draft authors - one of them is also a co-inventor of the patent - already discussed of this situation with the involved entity during the draft revision process and explained their point of view regarding the relationship between the draft - which is not aiming at Standards Track - and the patent. Moreover, they proposed sending at that time an IPR disclosure, if needed.
In any case, the way for encrypting the certificate during key exchange protocols (i.e., TLS) is not new and had been said many times before the patent publication date. Below some non-exclusive publications that enable identity protection by asymmetrically or symmetrically encrypting the certificate using a secret key computed during the key exchange establishment. Some of them compute the key to encrypt the certificate, in the same way as the patent proposes today.
1- Adding client identity protection to TLS (2000): available at http://www.imc.org/ietf-tls/mail-archive/msg02004.html: It consists of sending the ChangeCipherSpec message before the Certificate and the CertificateVerify messages and after the ClientKeyExchange message. The ChangeCipherSpec message is sent to notify the receiving party that subsequent messages will be protected under the cipher suite and keys negotiated during the TLS Handshake. The keys are computed by applying the PRF on the premaster secret and on the random values generated by both the client and the server, as described in TLS and SSL documents.
2- Beller-Yacobi protocol (1997): described in "Handbook of applied cryptography", CRC PRESS SERIES ON DISCRETE MATHEMATICES AND ITS APPLICATIONS, BOXA RATON, FL, CRC PRESS, US, 1997, pages 37- 39, 428, XP002204463, ISBN 0-8493-8523-7.
3- Aura T, Ellison C, "Privacy and Accountability in Certificate Systems", Research reports 61, [online], April 2000, htpp://www.citeseer.ist.psu.edu/cs. This document describes an authentication mechanism in which the client certificate is sent encrypted.
4- Samfat D, et. al., "Untraceability in Mobile Network", Mobicom proceeding, 1995, pages 26-36.
5- US Patent 6189098 - Client/server protocol for proving authenticity (2001), Figures 3a, 3b. This patent also describes a way to symmetrically encrypt the certificate by its owner before sending it over the wire.
6- http://www.niksula.cs.hut.fi/~sjsavola/SoN/essay.html (1999), Identity Protection Exchange: The Identity Protection Exchange is designed to separate the Key Exchange information from the identity and authentication related information. A common share secret can be established before identification and authentication related information is exchanged and encryption provides protection of the communicating identities.
7- Just Fast Keying (JFKi, 2003), http://people.csail.mit.edu/canetti/materials/jfk.pdf, computes a secret key from DH exchange and encrypts the certificate with this key.
8- The SIGMA protocol (2001), idem for JFK.
9- http://pastel.paristech.org/1168/01/these_ibrahim_02-04-05.pdf (French document, 2004), see Chapter 6. |