Editing HMAC (section)

{{Short description|Computer communications authentication algorithm}}
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[[File:SHAhmac.svg|thumb|upright=1.5|HMAC-SHA1 generation]]

In [[cryptography]], an '''HMAC''' (sometimes expanded as either '''keyed-hash message authentication code''' or '''hash-based message authentication code''') is a specific type of [[message authentication code]] (MAC) involving a [[cryptographic hash function]] and a secret cryptographic key. As with any MAC, it may be used to simultaneously verify both the [[data integrity]] and authenticity of a message. An HMAC is a type of keyed hash function that can also be used in a key derivation scheme or a key stretching scheme.

HMAC can provide authentication using a [[shared secret]] instead of using [[digital signature]]s with [[Public-key cryptography|asymmetric cryptography]]. It trades off the need for a complex [[public key infrastructure]] by delegating the key exchange to the communicating parties, who are responsible for establishing and using a trusted channel to agree on the key prior to communication.