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message authentication code

A fingerprint made with a shared secret, proving the message came from a key holder.

A MAC (e.g. HMAC-SHA256) gives integrity and authenticity between holders of one shared key, but no confidentiality and no proof to a third party.

Examples

  • HMAC-SHA256 with a secret shared by a node and the back end lets the back end know a reading came from a key holder.

  • A MAC can't prove to a third party which side sent the message, because both holders of the key can make the same tag.

See also

hash function digital signature non-repudiation
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