newgen.py

import json
from sympy import mod_inverse, Pow

from fractions import Fraction

def mod_add(a, b, prime):
    return (a + b) % prime

def mod_sub(a, b, prime):
    return (a - b) % prime

def mod_mul(a, b, prime):
    return (a * b) % prime

def mod_inverse(a, prime):
    return pow(a, -1, prime)

def mod_div(a, b, prime):
    inverse_b = mod_inverse(b, prime)
    return mod_mul(a, inverse_b, prime)

def lagrange_interpolation(points,prime):
    if not points or len(points[0]) != 2:
        raise ValueError("Invalid input. Expected a 2D array with each row containing a point (x, y).")

    M = len(points)
    x_values, y_values = zip(*points)

    def calculate_lagrange_term(i, x):
        term = Fraction(1, 1)
        for j in range(M):
            if i != j:
                term = mod_mul(term,mod_div(x - x_values[j], x_values[i] - x_values[j],prime),prime)
                # term *= Fraction(x - x_values[j], x_values[i] - x_values[j])
        return term

    def generate_secret(x):
        secret = Fraction(0, 1)
        for i in range(M):
            secret = mod_add(secret,mod_mul(y_values[i], calculate_lagrange_term(i, x),prime),prime)
            # secret += y_values[i] * calculate_lagrange_term(i, x)
        return secret

    return generate_secret

with open('data.json', 'r') as file:
    data = json.load(file)
    k = data["k"]
    n = data["n"]
    shares_list = data["shares"]
    shares = [[share["value"]["value"] for share in shares_list]]
    print(shares)
    prime = int(data["shares"][0]["value"]["prime"], 16)
    hex_2d_array = [[share["index"], int(share["value"]["value"], 16)] for share in shares_list]
    print(hex_2d_array)
    interpolate = lagrange_interpolation(hex_2d_array,prime)
    print(interpolate(0))
    p = interpolate(0) % prime
    h = hex(int(p))
    print(p)