Presentation 2019-11-01
Character on elliptic curves over finite fields and even-oddness of the order of points
Masaaki Shirase,
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Abstract(in Japanese) (See Japanese page)
Abstract(in English) Let $p$ be a prime $ge 5$, $q$ be a power of $p$, and $Fq$ be a finite field with $q$ elements. Let $E/Fq$ be an elliptic curve, $#E(Fq)$ is an even number, and a point $P_0$ having order 2 is given, where $#$ means the number of elements. In a previous study, it is shown that a homomorphism map (or character) $chi_E: E(Fq) rightarrow {1, -1 }$ is defined using the coordinate of $P_0$, the Legendre symbol, and the norm. The main result of the previous study is that when $#E(Fq)=2 times$ odd, if $chi_E^{-1}(-1)ne emptyset$ then $Pin E(Fq)mbox{ has odd order}Leftrightarrow chi_E(P)=1$ holds. Also another proposition in the previous study needs the condition, lqlq if $chi_E^{-1}(-1)ne emptyset$.'' This report shows that if (a) $#E(Fp)=2times$ odd, or (b) $#E(Fq)[2]=4$ and $#E(Fq)=4times$ odd, then $chi_E^{-1}(-1)ne emptyset$. Also, this report shows if (b) holds then three characters are defined, and it holds that $P in E(Fq) mbox{ has odd order }Leftrightarrow chi_{E0}(P) =chi_{E1}(P)=1$, where $chi_{E0}$ and $chi_{E1}$ are two characters of them.
Keyword(in Japanese) (See Japanese page)
Keyword(in English) Elliptic curve / Finite field / Character / Order / Legendre symbol
Paper # ISEC2019-66,SITE2019-60,LOIS2019-25
Date of Issue 2019-10-25 (ISEC, SITE, LOIS)

Conference Information
Committee ISEC / SITE / LOIS
Conference Date 2019/11/1(2days)
Place (in Japanese) (See Japanese page)
Place (in English) Osaka Univ.
Topics (in Japanese) (See Japanese page)
Topics (in English)
Chair Shiho Moriai(NICT) / Tetsuya Morizumi(Kanagawa Univ.) / Tomohiro Yamada(NEL)
Vice Chair Shoichi Hirose(Univ. of Fukui) / Tetsuya Izu(Fujitsu Labs.) / Masaru Ogawa(Kobe Gakuin Univ.) / Takushi Otani(Kibi International Univ.) / Toru Kobayashi(Nagasaki Univ.)
Secretary Shoichi Hirose(NICT) / Tetsuya Izu(Tsukuba Univ.) / Masaru Ogawa(Toyo Eiwa Univ.) / Takushi Otani(KDDI Research) / Toru Kobayashi(Research Organization of Information and Systems)
Assistant Dai Yamamoto(Fujitsu Labs.) / Yuuji Suga(IIJ) / Nobuyuki Yoshinaga(Yamaguchi Pref Univ.) / Daisuke Suzuki(Hokuriku Univ.) / Kenichi Arai(Nagasaki Univ.)

Paper Information
Registration To Technical Committee on Information Security / Technical Committee on Social Implications of Technology and Information Ethics / Technical Committee on Life Intelligence and Office Information Systems
Language JPN
Title (in Japanese) (See Japanese page)
Sub Title (in Japanese) (See Japanese page)
Title (in English) Character on elliptic curves over finite fields and even-oddness of the order of points
Sub Title (in English)
Keyword(1) Elliptic curve
Keyword(2) Finite field
Keyword(3) Character
Keyword(4) Order
Keyword(5) Legendre symbol
1st Author's Name Masaaki Shirase
1st Author's Affiliation Future University Hakodate(FUN)
Date 2019-11-01
Paper # ISEC2019-66,SITE2019-60,LOIS2019-25
Volume (vol) vol.119
Number (no) ISEC-257,SITE-258,LOIS-259
Page pp.pp.25-32(ISEC), pp.25-32(SITE), pp.25-32(LOIS),
#Pages 8
Date of Issue 2019-10-25 (ISEC, SITE, LOIS)