Lecture 10 , Zero Knowledge Proofs , Secure Computation

Relating Message Authentication Codes and Digital Signatures Digital signature schemes and message authentication codes are both used to ensure the secure authentication of transmitted messages. While message authentication codes do so in a private-key setting, digital signature schemes are the public-key parallel, ensuring secure authentication in a public key setting. Their syntax and security guarantees are analogous, but digital signatures allow us to do more. Digital signatures eliminate the need to share distinct secret keys between the sender and each potential receiver, allowing the sender to publish only one verification key that can be used for all subsequent signatures and they all can be publicly verified by all recipients of the messages and their attached signatures. As in the case of private-key vs. public-key encryption, message authentication codes are shorter and more efficient than digital signatures. Thus, if the sender primarily communicates with only one recipient it is better to share a secret key and use message authentication codes for subsequent authentications.