Genus-1 curves over large-characteristic fields

Twisted Edwards curves

a*x^^{2}+y^^{2}=1+d*x^^{2}*y^^{2}

Extended coordinates [database entry] represent x y as X Y Z T satisfying the following equations:

x=X/Z y=Y/Z x*y=T/Z

This representation was introduced in the Hisil–Wong–Carter–Dawson paper "Twisted Edwards curves revisited" (Asiacrypt 2008).

- 9M for addition: 9M. 9M.
- 8M for addition with Z2=1: 8M. 8M.
- 7M for addition with Z1=1 and Z2=1: 7M.
- 9M for readdition: 9M after 9M. 9M after 9M.
- 8M for readdition with Z2=1: 8M after 8M. 8M after 8M.
- 7M for readdition with Z1=1 and Z2=1: 7M after 7M.
- 8M for doubling: 4M+4S.
- 7M for doubling with Z1=1: 3M+4S.
- 14M for tripling: 11M+3S.

- 9M for addition: 9M. 9M.
- 8M for addition with Z2=1: 8M. 8M.
- 7M for addition with Z1=1 and Z2=1: 7M.
- 9M for readdition: 9M after 9M. 9M after 9M.
- 8M for readdition with Z2=1: 8M after 8M. 8M after 8M.
- 7M for readdition with Z1=1 and Z2=1: 7M after 7M.
- 7.2M for doubling: 4M+4S.
- 6.2M for doubling with Z1=1: 3M+4S.
- 13.4M for tripling: 11M+3S.

- 9M for addition: 9M. 9M.
- 8M for addition with Z2=1: 8M. 8M.
- 7M for addition with Z1=1 and Z2=1: 7M.
- 9M for readdition: 9M after 9M. 9M after 9M.
- 8M for readdition with Z2=1: 8M after 8M. 8M after 8M.
- 7M for readdition with Z1=1 and Z2=1: 7M after 7M.
- 6.68M for doubling: 4M+4S.
- 5.68M for doubling with Z1=1: 3M+4S.
- 13.01M for tripling: 11M+3S.

Operation | Assumptions | Cost | Readdition cost |
---|---|---|---|

addition | Z1=1 and Z2=1 | 7M + 1*a | 7M + 1*a |

addition | Z1=1 and Z2=1 | 7M + 1S + 1*a + 1*d | 7M + 1S + 1*a |

addition | Z2=1 | 8M + 1*a | 8M + 1*a |

addition | Z2=1 | 8M + 1*a + 1*d | 8M + 1*a |

addition | 9M + 1*a | 9M + 1*a | |

addition | 9M + 1*a + 1*d | 9M + 1*a | |

doubling | Z1=1 | 3M + 4S + 1*a | |

doubling | 4M + 4S + 1*a | ||

tripling | 11M + 3S + 1*a |

- Assumptions: Z1=1 and Z2=1.
- Cost: 7M + 1*a + 7add.
- Cost: 7M + 1*a + 6add dependent upon the first point.
- Source: 2008 Hisil–Wong–Carter–Dawson, http://eprint.iacr.org/2008/522, Section 3.2, plus assumption Z1=1.
- Explicit formulas:
A = X1*X2 B = Y1*Y2 C = T2 D = T1 E = D+C F = (X1-Y1)*(X2+Y2)+B-A G = B+a*A H = D-C X3 = E*F Y3 = G*H T3 = E*H Z3 = F*G

- Assumptions: Z1=1 and Z2=1.
- Cost: 7M + 1S + 1*a + 1*d + 8add.
- Cost: 7M + 1S + 1*a + 7add dependent upon the first point.
- Source: 2008 Hisil–Wong–Carter–Dawson, http://eprint.iacr.org/2008/522, Section 3.1, plus assumption Z1=1, plus standard simplification.
- Strongly unified.
- Explicit formulas:
A = X1*X2 B = Y1*Y2 C = T1*d*T2 E = (X1+Y1)*(X2+Y2)-A-B F = 1-C G = 1+C H = B-a*A X3 = E*F Y3 = G*H T3 = E*H Z3 = 1-C^

^{2}

- Assumptions: Z2=1.
- Cost: 8M + 1*a + 7add.
- Cost: 8M + 1*a + 6add dependent upon the first point.
- Source: 2008 Hisil–Wong–Carter–Dawson, http://eprint.iacr.org/2008/522, Section 3.2.
- Explicit formulas:
A = X1*X2 B = Y1*Y2 C = Z1*T2 D = T1 E = D+C F = (X1-Y1)*(X2+Y2)+B-A G = B+a*A H = D-C X3 = E*F Y3 = G*H T3 = E*H Z3 = F*G

- Assumptions: Z2=1.
- Cost: 8M + 1*a + 1*d + 7add.
- Cost: 8M + 1*a + 6add dependent upon the first point.
- Source: 2008 Hisil–Wong–Carter–Dawson, http://eprint.iacr.org/2008/522, Section 3.1.
- Strongly unified.
- Explicit formulas:
A = X1*X2 B = Y1*Y2 C = T1*d*T2 D = Z1 E = (X1+Y1)*(X2+Y2)-A-B F = D-C G = D+C H = B-a*A X3 = E*F Y3 = G*H T3 = E*H Z3 = F*G

- Cost: 9M + 1*a + 7add.
- Cost: 9M + 1*a + 6add dependent upon the first point.
- Source: 2008 Hisil–Wong–Carter–Dawson, http://eprint.iacr.org/2008/522, Section 3.2.
- Explicit formulas:
A = X1*X2 B = Y1*Y2 C = Z1*T2 D = T1*Z2 E = D+C F = (X1-Y1)*(X2+Y2)+B-A G = B+a*A H = D-C X3 = E*F Y3 = G*H T3 = E*H Z3 = F*G

- Cost: 9M + 1*a + 1*d + 7add.
- Cost: 9M + 1*a + 6add dependent upon the first point.
- Source: 2008 Hisil–Wong–Carter–Dawson, http://eprint.iacr.org/2008/522, Section 3.1.
- Strongly unified.
- Explicit formulas:
A = X1*X2 B = Y1*Y2 C = T1*d*T2 D = Z1*Z2 E = (X1+Y1)*(X2+Y2)-A-B F = D-C G = D+C H = B-a*A X3 = E*F Y3 = G*H T3 = E*H Z3 = F*G

- Assumptions: Z1=1.
- Cost: 3M + 4S + 1*a + 7add + 1*2.
- Source: 2008 Hisil–Wong–Carter–Dawson, http://eprint.iacr.org/2008/522, Section 3.3, plus assumption Z1=1, plus standard simplification.
- Explicit formulas:
A = X1^

^{2}B = Y1^^{2}D = a*A E = (X1+Y1)^^{2}-A-B G = D+B H = D-B X3 = E*(G-2) Y3 = G*H T3 = E*H Z3 = G^^{2}-2*G

- Cost: 4M + 4S + 1*a + 6add + 1*2.
- Source: 2008 Hisil–Wong–Carter–Dawson, http://eprint.iacr.org/2008/522, Section 3.3.
- Explicit formulas:
A = X1^

^{2}B = Y1^^{2}C = 2*Z1^^{2}D = a*A E = (X1+Y1)^^{2}-A-B G = D+B F = G-C H = D-B X3 = E*F Y3 = G*H T3 = E*H Z3 = F*G

- Cost: 11M + 3S + 1*a + 7add + 2*2.
- Source: 2015 Chuengsatiansup.
- Explicit formulas:
YY = Y1^

^{2}aXX = a*X1^^{2}Ap = YY+aXX B = 2*(2*Z1^^{2}-Ap) xB = aXX*B yB = YY*B AA = Ap*(YY-aXX) F = AA-yB G = AA+xB xE = X1*(yB+AA) yH = Y1*(xB-AA) zF = Z1*F zG = Z1*G X3 = xE*zF Y3 = yH*zG Z3 = zF*zG T3 = xE*yH