Digital Signature

Learn about message authentication, message integrity, and non-repudiation and how a digital signature system ensures these.

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.

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