Other ways to determine the validity of a public key

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Public key 3, 4 fits the equation of y^2 = x^2 + 7

Yet this comes up as an "invalid public key". How is that invalid? Sure, it deviates extremely from other numbers, but what other equations are being applied to the public key to determine its validity?

Mine

Posted 2014-07-13T17:27:15.233

Reputation: 1 142

1The formula is y^2 = x^3 + 7. I don't think there are any small-number solutions.Pieter Wuille 2014-07-13T18:45:09.913

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Not sure this is what you are talking about, but apparently y^2=x^3+7 has no integral solutions.

Murch 2014-07-14T15:05:11.873

1That's OK because secp256k1 doesn't just use plain integers, the equation above is evaluated with integers modulo a very large prime N. Really the equation is: y^2 = x^3 + 7 mod N.David Grayson 2015-02-02T18:46:22.017

Answers

1

You got the formula wrong.

The correct formula is

y2 = x3 + 7 mod N

where N is a very large prime.

Murch

Posted 2014-07-13T17:27:15.233

Reputation: 41 609