Why Point Addition and Point Doubling return different points for the same number of P? Like the value of 8P is different when doubling 4P and when adding 4P and 4P in the code below.
I've used this Python library for Elliptic curve point multiplication
My Code:
G2 = ECdouble(GPoint)print 'G2 \t\t '+ str(G2[0])G4 = ECdouble(G2)print 'G4 \t\t '+ str(G4[0])G8 = ECdouble(G4)print 'G8 \t\t '+ str(G8[0])G8ByAddition = ECadd(G4,G4)print 'G8ByAddition \t '+ str(G8ByAddition[0])Output:
Why is the G8 value different from G8ByAddition? Have I understood the point multiplication concept wrong?