IPR Details
Riad S. Wahby's Statement about IPR related to draftirtfcfrghashtocurve belonging to Idemia Identity and Security France SAS
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I. Possible Patent Holder/Applicant ("Patent Holder")
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Idemia Identity and Security France SAS  Holder legal name  Idemia Identity and Security France SAS 
II. Contact Information for the IETF Participant Whose Personal Belief Triggered this Disclosure
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Riad S. Wahby  Name  Riad S. Wahby 
rsw@jfet.org  rsw@jfet.org  
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III. IETF Document or Other Contribution to Which this IPR Disclosure Relates
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IV. Disclosure of Patent Information
i.e., patents or patent applications required to be disclosed by RFC 8179
A. For granted patents or published pending patent applications, please provide the following information:
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Date: 20140506 
Patent, Serial, Publication, Registration, or Application/File number(s) 
Date: 20140506 
B. Does this disclosure relate to an unpublished pending patent application?:
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Has patent pending  No 
V. Contact Information of Submitter of this Form
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Riad S. Wahby  Submitter name  Riad S. Wahby 
rsw@jfet.org  Submitter email  rsw@jfet.org 
VI. Other Notes
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Additional notes 
Remediation: In draftirtfcfrghashtocurve05 and thereafter, the "Simplified SWU" method will be further differentiated from the algorithm described in Claim 13. A detailed discussion is available here: https://mailarchive.ietf.org/arch/msg/cfrg/jV4Wr4fbMKkd4vzsbEhKbous16Y To briefly summarize: Claim 13 is based on Skalba's equation, f(X1(t)) * f(X2(t)) * f(X3(t)) = U(t)^2 for polynomials X1, X2, X3, and U defined over a finite field F. In the method of Claim 13, the polynomial X3(t) is selected such that f(X3(t)) is nonsquare in F for all elements t in F. This method further describes an algorithm for evaluating the map that results from this choice of polynomials. In draft 05 and after, the hashtocurve standard lists criteria for selection of a constant Z for which there does not exist any polynomial X3 such that f(X3(t)) == Z for any t in F, and replaces Skalba's equation with the following simplified equation: f(X1(t)) * f(X2(t)) * Z = U(t)^2 To reiterate, it is impossible to arrive at the above equation by following the method described in Claim 13: that method entails selecting a polynomial X3, whereas by construction such a polynomial does not exist in the method described in draftirtfcfrghashtocurve05 and later drafts. 
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