cryptotools/examples/elliptic/point_at_infinity.py

44 lines
898 B
Python

#!/usr/bin/env python3
from Cryptotools.Groups.point import Point
from Cryptotools.Groups.curve import Curve
import numpy as np
import matplotlib.pyplot as plt
from math import sqrt
a = 3
b = 8
curve = Curve(a, b, Curve.WEIERSTRASS)
x = curve.x
curve.generatePoints()
y = curve.y
yn = curve.yn
points = curve.getPoints()
pointsReverse = curve.getPointsSym()
P = points[10]
Q = curve.find_reverse(P)
# We made the addition
# The result is the point at infinity
R = curve.add(P, Q)
print(f"{R.x} {R.y}")
plt.figure(figsize=(10, 6))
plt.plot(x, y, color='b', label=f'$y^2 = x^3 + {a}x + {b}$')
plt.plot(x, yn, color='b', )
plt.plot(P.x, P.y, marker='o', color="red")
plt.annotate('P', (P.x, P.y + 0.5))
plt.plot(Q.x, Q.y, marker='o', color="red")
plt.text(-1 , 11, f"R = infinity")
plt.annotate('Q', (Q.x, Q.y + 0.5))
plt.axline([P.x, P.y], [Q.x, Q.y], color="red")
plt.legend()
plt.show()