Schnorr Signature

Schnorr signatures are a form of digital signature designed to prove ownership of a private key, similar in purpose to ECDSA, which Bitcoin has used since its early days. However, Schnorr signatures offer several notable advantages that have led to their adoption in Bitcoin through the Taproot upgrade.

One key improvement is security—Schnorr signatures are provably secure and robust against signature malleability, a vulnerability present in ECDSA. Schnorr also allows for signature and public key aggregation, enabling multiple signers to combine their signatures into one. This leads to greater efficiency, reduced verification time, and the ability to batch-verify multiple signatures at once.

Privacy is another benefit: by combining signatures, it becomes more difficult to determine how many parties were involved in authorizing a transaction. Additionally, Schnorr signatures are generally smaller in size than ECDSA signatures, resulting in lower transaction fees.

When Bitcoin was developed, the Schnorr signature algorithm was still covered by a patent, so Satoshi Nakamoto selected ECDSA instead. Now that the patent has expired, Schnorr signatures are being integrated into Bitcoin to improve efficiency, privacy, and network scalability.