Digital Signature

A digital signature is an electronic, cryptographic method of signing a message or document. A valid digital signature provides a reason for the receiver to assume that the message originated by a recognized sender, that the sender cannot deny having written the message, and that the message was not modified in transit.

To remember these useful properties, let’s give them names:

• Authenticity ensures that a message is from the signer that it claims to be from.

• Integrity ensures that a message has not been tampered with after the signing.

• Non-repudiation ensures that the signer cannot later deny sending the message.

Digital signatures are typically used when sending a message between two parties:

• a sender, who signs a message.

• a recipient, who verifies the message.