How to generate a public key from a private ECDSA key? Having some specific ECDSA curve and a private key, how does one calculate the public key? I am having a hard time finding the algorithm and equations for it.
The write up on Wikipedia is pretty good. I won't go into all the detail that they do there, but your private key is a randomly selected integer $d_A$ selected from $[1,n-1]$ where $n$ is the order of the group. The public key is $Q_A=d_AG$ where $G$ is the base point on the curve defined in the publicly agreed upon parameters.