# Using the a multiple of the x coordinate as a private key

ECDSA specs require private key ($d$) to be a random integer ($r$) in the range $[1, N-1]$, where $N$ is the order of the base point ($G$). What if the private key instead is set to the x-coordinate of the EC point $r \cdot G$ (i.e., $G$ added $r$ times)?

• That’s effectively the formula for the public key. You’d need to pretty much change everything. – bartonjs May 11 '18 at 17:18

What if the private key instead is set to the x-coordinate of the EC point $r\cdot G$