calculate.py

def h(n):
    return hex(n).replace("0x","")

def extended_gcd(aa, bb):
    lastremainder, remainder = abs(aa), abs(bb)
    x, lastx, y, lasty = 0, 1, 1, 0
    while remainder:
        lastremainder, (quotient, remainder) = remainder, divmod(lastremainder, remainder)
        x, lastx = lastx - quotient*x, x
        y, lasty = lasty - quotient*y, y
    return lastremainder, lastx * (-1 if aa < 0 else 1), lasty * (-1 if bb < 0 else 1)

def modinv(a, m):
    g, x, y = extended_gcd(a, m)
    if g != 1:
        raise ValueError
    return x % m
    
N = 0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141


K = 0x7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a0
R = 0x00000000000000000000003b78ce563f89a0ed9414f5aa28ad0d96d6795f9c63
S = 0x0a963d693c008f0f8016cfc7861c7f5d8c4e11e11725f8be747bb77d8755f1b8
Z = 0x521a65420faa5386d91b8afcfab68defa02283240b25aeee958b20b36ddcb6de


print (h((((S * K) - Z) * modinv(R,N)) % N))