How to generate a public key from a private key using Elliptic Curve Digital Signature Algorithm I'm trying to understand the graphical basis that underlies the discreet logarithmic Elliptic Curve Digital Signature Algorithm (ECDSA) introduced in Chapter 4 of "Mastering Bitcoin" by Andreas Antonopolous: https://github.com/aantonop/bitcoinbook/blob/develop/ch04.asciidoc

Andreas says a point in an elliptic curves can be added to itself by drawing a tangent, finding the intersection, then reflecting the new point on the x-axis. This makes no sense to me, but for now I'll just blindly believe. Then K = k * G, where k is the private key, G is a constant "Generator Point" and K is the public key. 

Then he shows the attached figure which graphically shows how to get from G to 8G.


Is "8" the private key in this example?
Given K and G, it doesn't seem like this function would be irreversible. Am I missing something or does it only become irreversible in the discrete logarithmic equivalent.
Yes.
Imagine that all you can see is the point at G, and the point at 8G. You're trying to determine how many times the point was added. And the number isn't 8, it's somewhere between 1 and 2^256.



  Am I missing something or does it only become irreversible in the discrete logarithmic equivalent.


I have no idea what that means; I'll leave that for someone else to answer.