Can We Derive X from Y in Bitcoin?

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boss2009Newbie
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#1Sep 30, 2017, 05:01 AM
If we have the y coordinate, can we figure out x? I feel like there must be a way.
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0xVaultNewbie
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#2Sep 30, 2017, 06:48 AM
No way that's possible. Just doesn't work like that.
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boss2009Newbie
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#3Sep 30, 2017, 07:52 AM
Why not? There’s gotta be some formula out there.
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#4Sep 30, 2017, 01:02 PM
There might be but it’s tricky. For every x, there are three possible y values, kinda like how you have two roots in a square root scenario. Just basic algebra.
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boss2009Newbie
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#5Sep 30, 2017, 03:52 PM
Can you break down the formula you’re talking about?
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stacksatsHero Member
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#6Sep 30, 2017, 08:22 PM
Well, solving cubic equations modulo a large prime is tough, especially with secp256k1. No known polynomial-time algorithm exists for this, so finding x from y is a real challenge.
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boss2009Newbie
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#7Oct 2, 2017, 05:34 AM
Thanks for the info. I heard somewhere that it’s impossible to derive x from y.
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Posts: 110 · Reputation: 19
#8Oct 2, 2017, 08:51 AM
Yeah, it’s not just hard, it’s nearly impossible. Saw some people trying to explain it earlier.
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boss2009Newbie
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#9Oct 2, 2017, 11:33 AM
Anyone know if it’s possible to get the private key from these public keys? What do you think about this?
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stacksatsHero Member
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#10Oct 2, 2017, 12:08 PM
I tried finding x1 = 1 once. Honestly, those points are pretty much a mystery to everyone. Finding them is super tough.
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