ECDSA: Elliptic Curve Signatures (2024)

It is important to know that the ECDSA signature scheme allows the public key to be recovered from the signed message together with the signature. The recovery process is based on some mathematical computations (described in the

SECG: SEC 1

standard) and returns 0, 1 or 2 possible EC points that are valid public keys, corresponding to the signature. To avoid this ambiguity, some ECDSA implementations add one additional bit v to the signature during the signing process and it takes the form {r, s, v}. From this extended ECDSA signature {r, s, v} + the signed message, the signer's public key can be restored with confidence.