The ECDSA key-pair consists of:
- private key (integer): privKey
- public key (EC point): pubKey = privKey * G
The private key is generated as a random integer in the range [0...n-1]. The public key pubKey is a point on the elliptic curve, calculated by the EC point multiplication: pubKey = privKey * G (the private key, multiplied by the generator point G).
The public key EC point {x, y} can be compressed to just one of the coordinates + 1 bit (parity). For the secp256k1 curve, the private key is 256-bit integer (32 bytes) and the compressed public key is 257-bit integer (~ 33 bytes).