OK Thanks again I just realize that there are 2 points with x = 17: 7 * G = (17,9) and 24*g = (17,20) And for the exemple in http://www.royalforkblog.com/2014/09/04/ecc/ the point I was looking for is (17,9)!!!
My goal is to verify a signature in a bitcoin transaction. I need a public Key which is a point on the elliptic curve: pubKeyPoint = privateKey * G = (X, Y) where G is the generator point. In a transaction we can find X and Y but sometimes only X. Same for the ramdom number. In order to sign a transaction the user pick a random number RN and compute RN * G = (RNx, RNy). Only RNx is given in a transaction. In order to verify the validity of a signature, I must find Y and RNy. I don't see other way to do it. In this case p is very large: is there a non-negligible risk of collision like (17,9) and (17,20) ? -- -- You received this message because you are subscribed to the "Crypto++ Users" Google Group. To unsubscribe, send an email to [email protected]. More information about Crypto++ and this group is available at http://www.cryptopp.com. --- You received this message because you are subscribed to the Google Groups "Crypto++ Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
