Digital Signatures and Authorship
TL;DR
Digital signatures prove that a message was created by a specific sender and has not been altered, providing “unforgeable authorship.”
What Is It?
A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. It uses Asymmetric Cryptography:
- Private Key: Used to “sign” the message. Only the owner knows it.
- Public Key: Used by anyone to “verify” that the signature matches the message and the private key.
Why Does It Matter?
In Bitcoin, digital signatures are used to prove ownership of coins. When you send bitcoin, you are signing a message that says: “I, the owner of this public key, authorize the transfer of these funds to a new public key.” Without digital signatures, anyone could pretend to be you and spend your money (Identity Theft).
Key Properties
- Authenticity: You know who sent it.
- Non-repudiation: The sender cannot deny signing it later.
- Integrity: If even one bit of the message changes, the signature becomes invalid.