The Generalized Montgomery Coordinate: A New Computational Tool for Isogeny-based Cryptography
The Generalized Montgomery Coordinate: A New Computational Tool for Isogeny-based Cryptography
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发表时间:
2022
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通讯作者:
Tomoki Moriya;Hiroshi Onuki;Yusuke Aikawa;T. Takagi
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作者:
Tomoki Moriya;Hiroshi Onuki;Yusuke Aikawa;T. Takagi
. Recently, some studies have constructed one-coordinate arith-metics on elliptic curves. For example, formulas of the x -coordinate of Montgomery curves, x -coordinate of Montgomery − curves, w -coordinate of Edwards curves, w -coordinate of Hu(cid:11)’s curves, ω -coordinates of twisted Jacobi intersections have been proposed. These formulas are useful for isogeny-based cryptography because of their compactness and e(cid:14)ciency. In this paper, we de(cid:12)ne a novel function on elliptic curves called the generalized Montgomery coordinate that has the (cid:12)ve coordinates described above as special cases. For a generalized Montgomery coordinate, we construct an explicit formula of scalar multiplication that includes the division polynomial, and both a formula of an image point under an isogeny and that of a coe(cid:14)cient of the codomain curve. Finally, we present two applications of the theory of a generalized Mont-gomery coordinate. The (cid:12)rst one is the construction of a new e(cid:14)cient formula to compute isogenies on Montgomery curves. This formula is more e(cid:14)cient than the previous one for high degree isogenies as the √ (cid:19)elu’s formula in our implementation. The second one is the construction of a new generalized Montgomery coordinate for Montgomery − curves used for CSURF.