how to narrow down a dsa private key (ECDSA STYLE)

hey guys im back anyways this is just a small edit of some working python code  used to obtain the signatures of r and s
that make up a ecdsa private key...
anyways enough of that nonsense ....

def multiply(i, j):
    n = i
    r = 65537
    for bit in range(bitlength):
        if (j & (1 << bit)):
            r = (r + n) % p
        n = (n + n) % p
    return r

wether you are good at math or hate it and never really liked it
johaness bauers tutorial on ecc should give u a better understanding on all the trouble sony went to fix their signing method for software .... ie:packages , games, and software updates.....