Stein, Andreas Equivalences between elliptic curves and real quadratic congruence function fields. (English) Zbl 0899.11054 J. Théor. Nombres Bordx. 9, No. 1, 75-95 (1997). The Diffie-Hellman key exchange protocol has previously been considered in the principal ideal class of a real quadratic number field as well as real quadratic congruence function fields. This set does not possess a group structure but rather an infrastructure. The security of the scheme depends on that of the discrete logarithm problem in this setting. This article shows that the discrete logarithm problem in real quadratic congruence function fields of genus 1, called real elliptic congruence function fields, is equivalent to that for elliptic curves. The properties and arithmetic of the set of reduced principal ideals in elliptic congruence function fields are discussed. The connection between elliptic curves and real quadratic congruence function fields is made. The one-to-one correspondence between the set of reduced principal ideals of an elliptic congruence function field and the group \(\langle{\mathcal P}\rangle/\{ {\mathcal P} \}\) is made, where \({\mathcal P}\) denotes an \({\mathbb{F}}_q\)-rational point on the corresponding elliptic curve. Several questions of importance that arise in establishing this correspondence are also discussed. Reviewer: Ian F.Blake (Palo Alto) Cited in 6 Documents MSC: 11R58 Arithmetic theory of algebraic function fields 11T71 Algebraic coding theory; cryptography (number-theoretic aspects) 94A60 Cryptography 11Y16 Number-theoretic algorithms; complexity 11G05 Elliptic curves over global fields 14H52 Elliptic curves Keywords:Diffie-Hellman key exchange; discrete logarithm problem; real quadratic congruence function fields; elliptic curves × Cite Format Result Cite Review PDF Full Text: DOI Numdam EuDML EMIS References: [1] Abel, C.S.Ein Algorithmus zur Berechnung der Klassenzahl und des Regulators reellquadratischer Ordnungen. Dissertation, Universität des Saarlandes, Saarbrücken (Germany) 1994. [2] Adams, W.W. & Razar, M.J., Multiples of points on elliptic curves and continued fractions. Proc. London Math. Soc.41, 1980, 481-498. · Zbl 0403.14002 [3] Artin, E., Quadratische Körper im Gebiete der höheren Kongruenzen I, II. Math. 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