Schnorr signatures are a fast, secure, and cost-effective cryptographic signature scheme used for transaction signing.
Schnorr signatures are a cryptographic signature scheme invented in 1991 by the German mathematician and cryptographer Claus Peter Schnorr. The invention remained patented until 2008, only becoming freely usable afterward.
This signature scheme is often utilized for its efficiency in terms of space and simplicity.
In cryptography, a digital signature is a method to ensure the integrity and authenticity of a message. Digital signatures provide a range of security attributes that make it virtually impossible to falsify the original data.
Schnorr signatures are more space-efficient compared to other digital signature schemes, such as the Elliptic Curve Digital Signature Algorithm (ECDSA), the alternative open-source version. Schnorr signatures were introduced into the Bitcoin protocol through the Taproot soft fork.
They have several advantageous properties compared to other methods of digital signatures:
- Efficiency: Schnorr signatures occupy less space compared to other digital signature systems, such as ECDSA (Elliptic Curve Digital Signature Algorithm). By reducing storage space within the block, Schnorr signatures contribute to better network scalability;
- Non–malleability: once the signature is created, no party involved in the transaction can modify or alter a signature to generate a double spend;
- Increased privacy: one of the advantages of Schnorr signatures is the ability to aggregate multiple keys within a transaction and produce a single unique signature, offering benefits not only in terms of fee savings but also in terms of privacy. For example, a multi-sig wallet requires multiple signatures to execute a transaction. All signatures are visible on the blockchain, so before the Taproot soft fork, all multi-sig wallets were easily identifiable. For example, a company using a 5-of-7 multi-sig wallet for managing their bitcoin would be part of a very small set of users using the same signature scheme, making it very easy to identify all transactions related to it.
With the activation of the Taproot soft fork, Schnorr signatures offer an alternative to the Elliptic Curve Digital Signature Algorithm (ECDSA), which has been used since the creation of Bitcoin.
In addition to Bitcoin, Schnorr signatures can be used for electronically signing documents, ensuring the integrity and authenticity of the document.
