Digital Signature
Definition
A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature gives a recipient very strong reason to believe that the message was created by a known sender (authentication), that the sender cannot deny having sent the message (non-repudiation), and that the message was not altered in transit (integrity).
Why It Matters
Digital signatures are the equivalent of a handwritten signature or a seal for the digital world. They are essential for secure software distribution, e-commerce, and legally binding digital contracts.
Contextual Example
When you download a software update from a trusted vendor like Microsoft or Apple, it is digitally signed. Your operating system can verify this signature to ensure that the update is authentic and has not been tampered with by a third party.
Common Misunderstandings
- Digital signatures are typically created using asymmetric cryptography (public/private keys). The sender signs with their private key, and the receiver verifies with the sender's public key.
- It provides authentication, integrity, and non-repudiation.