messagesigning

Message signing is a cryptographic process used to ensure the authenticity and integrity of a digital message. It involves using a sender's private key to create a unique digital signature that is then attached to the message. This signature acts as a form of electronic fingerprint for the message.

When a recipient receives a signed message, they can use the sender's corresponding public key to verify the signature. If the verification is successful, it confirms two key aspects. Firstly, it proves that the message originated from the claimed sender, as only their private key could have generated a signature verifiable by their public key. This is known as authentication. Secondly, it guarantees that the message has not been altered in transit. If even a single character of the message is changed, the signature verification will fail, indicating tampering.

Message signing is a fundamental component of secure digital communication and is widely used in various applications, including email security (like S/MIME and PGP), digital certificates, and secure financial transactions. It helps prevent impersonation and ensures that recipients can trust the content they receive. The process relies on asymmetric cryptography, where a pair of keys, one private and one public, are mathematically linked.