What Is the ‘R’ Value in an ECDSA Signature and How Is It Derived from ‘K’?

The 'R' value is the x-coordinate of the point on the elliptic curve resulting from the point multiplication of the nonce (k) and the base point (G). Mathematically, R = (k × G)x.

It is one of the two components of the ECDSA signature (R, S). Since 'R' is derived directly from 'k', if an attacker can determine 'k', they can predict 'R', which is part of the attack vector if 'k' is weak.