Any body know if it is possible to know point is positive or negative? Or it is imposssible to know?
Only after solving the DL for that point, otherwise it would be trivial to solve the DLP on that curve. In a way, there are no negative or positive points because of the modular group.
Agree that it will be trivial task to solve key, but not agree that there are no negative or positive points.
#3-5=-2
#3
ptX=0xf9308a019258c31049344f85f89d5229b531c845836f99b08601f113bce036f9
ptY=0x388f7b0f632de8140fe337e62a37f3566500a99934c2231b6cb9fd7584b8e672
#5
ptsubX=0x2f8bde4d1a07209355b4a7250a5c5128e88b84bddc619ab7cba8d569b240efe4
ptsubY=0xd8ac222636e5e3d6d4dba9dda6c9c426f788271bab0d6840dca87d3aa6ac62d6
sub_point = (ptsubX, (p-ptsubY))
print ("sub_point= (%x,%x)" % sub_point)
result = addpt((ptX,ptY),sub_point, p)
print ("result_point= (%x,%x)" % result)
result_point= (c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5,e51e970159c23cc65c3a7be6b99315110809cd9acd992f1edc9bce55af301705)
As you can see Y coordinate is not the same as for 2, because 2 is
(c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5,1ae168fea63dc339a3c58419466ceaeef7f632653266d0e1236431a950cfe52a)
So we can say that (c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5,e51e970159c23cc65c3a7be6b99315110809cd9acd992f1edc9bce55af301705)
is negative point on curve and
(c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5,1ae168fea63dc339a3c58419466ceaeef7f632653266d0e1236431a950cfe52a)
is positive. But any way if there no way to get sign it is no matter.
