ECDH.py

import hashlib

Pcurve = 2**256 - 2**32 - 2**9 - 2**8 - 2**7 - 2**6 - 2**4 - 1
N = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCEAF48A03BBFD25E8CD0364141
Acurve = 0; Bcurve = 7
Gx = 55066263022277343669578718895168534326250603453777594175500187360389116729240
Gy = 32670510020758816978083085130507043184471273380659243275938904335757337482424
GPoint = (Gx,Gy)

privKey = 0xAAAAA

def modinv(a,n=Pcurve):
    lm, hm = 1,0
    low, high = a%n,n
    while low >1:
        ratio = high/low
        nm, new = hm-lm*ratio, high-low*ratio
        lm, low, hm, high = nm, new, lm, low
    return lm%n

def ECadd(a,b):
    LamAdd = ((b[1]-a[1])*modinv(b[0]-a[0],Pcurve))%Pcurve
    x = (LamAdd*LamAdd-a[0]-b[0]) % Pcurve
    y = (LamAdd*(a[0]-x)-a[1]) % Pcurve
    return (x,y)

def ECdouble(a):
    Lam = ((3*a[0]*a[0]+Acurve)*modinv((2*a[1]),Pcurve))%Pcurve
    x = (Lam*Lam-2*a[0])%Pcurve
    y = (Lam*(a[0]-x)-a[1])%Pcurve
    return(x,y)

def EccMultiply(GenPoint, ScalarHex):
    if ScalarHex == 0 or ScalarHex >= N: raise Exeption("Invalid Scalar/Privat Key")