Re: Determine if a public key point y is negative or positive, odd or even?
can you write something more about these calculation methods
in ecc secp256k1
1/2 = 57896044618658097711785492504343953926418782139537452191302581570759080747169
7/2 = 57896044618658097711785492504343953926418782139537452191302581570759080747172
57896044618658097711785492504343953926418782139537452191302581570759080747172 / 57896044618658097711785492504343953926418782139537452191302581570759080747169 = 7
So the above method from @sss555 is not work to define the pubkey is odd or even. I already try many use method to separate odd and even but pattern to cyclic odd and even is always same.
7/2 - 1/2 = 3,
7 -3 = odd
remember we just have the pubkey as known variable, no decimal or pvkey
I talk abot this
1/2 = 57896044618658097711785492504343953926418782139537452191302581570759080747169
7/2 = 57896044618658097711785492504343953926418782139537452191302581570759080747172
just run ecctools from @Alberto
I using ecctools
another situation:
x = 0x123456789
b = 1
c = 0x100000000
Xx = x + b
Xx = Xx - c
# = 0x2345678a
print(hex(x-Xx))
output:
0xffffffff
[Program finished]
if know range of pubkey after subtraction it is posible or not, verify with brute in range ffffff,like in scrypt , brute 0xffffffff
anyone try their examples and you get fffff too