Schnorr Signatures Gain Ground on Bitcoin Network

For twelve years, Bitcoin relied solely on the Elliptic Curve Digital Signature Algorithm (ECDSA) for signing transactions. However, with the Taproot upgrade in November 2021, a new signature scheme was quietly introduced, Schnorr signatures, standardized as BIP340. By 2026, this second scheme is expected to handle more of the network's heavy lifting than most users realize.

ECDSA has been the default signing scheme for Bitcoin, Ethereum, and many TLS certificates since its inception. It builds a signature from a random nonce, private key, and message hash, producing two values, r and s, that are checked against the signer's public key. In contrast, Schnorr signatures compute a signature as s = k + e·x, where k is a nonce, e is a challenge hash, and x is the private key.

The difference in math between ECDSA and Schnorr shows up in signature size, verification speed, and how many keys can be combined into a single proof. Schnorr signatures are fixed at 64 bytes, whereas ECDSA's on-chain size ranges from 70-72 bytes due to DER encoding. Additionally, Schnorr is non-malleable by design, unlike ECDSA which was historically malleable but mitigated by the low-S rule.