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 ffff will be know range
but what about if "c" in my code wrong ?
subtraction cant give anything except pubkey in lower bits, I give illustration below use puzzle 130 with known decimal variable upper range and lower range.
# Another trial for p130
upper ranger
1,361,129,467,683,753,853,853,498,429,727,072,845,818
pvkey
1,103,873,984,953,507,439,627,945,351,144,005,829,577
lower range
680,564,733,841,876,926,926,749,214,863,536,422,908
Pvkey - lower range
1,103,873,984,953,507,439,627,945,351,144,005,829,577 - 680,564,733,841,876,926,926,749,214,863,536,422,908 = 423,309,251,111,630,512,701,196,136,280,469,406,669
680,564,733,841,876,926,926,749,214,863,536,422,908 - 423,309,251,111,630,512,701,196,136,280,469,406,669 = 257,255,482,730,246,414,225,553,078,583,067,016,239
423,309,251,111,630,512,701,196,136,280,469,406,669 - 257,255,482,730,246,414,225,553,078,583,067,016,239 = 166,053,768,381,384,098,475,643,057,697,402,390,430
257,255,482,730,246,414,225,553,078,583,067,016,239 - 166,053,768,381,384,098,475,643,057,697,402,390,430 = 91,201,714,348,862,315,749,910,020,885,664,625,809
the challenge is until lowest bit we only have 1 known variable in decimal