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HMAC

computer communications hash algorithm

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General referenceInterpretive dossier study · Crown Archives visual atlas
Record originEnglish Wikipedia
Text licenseCC BY-SA 4.0
Source revisionSep 22, 2026
Entity authorityQ1669397 ↗
Source-derived summary

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 signatures with 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.

Details

Any cryptographic hash function, such as SHA-2 or SHA-3, may be used in the calculation of an HMAC; the resulting MAC algorithm is termed HMAC-x, where x is the hash function used (e.g. HMAC-SHA256 or HMAC-SHA3-512). The cryptographic strength of the HMAC depends upon the cryptographic strength of the underlying hash function, the size of its hash output, and the size and quality (entropy) of the key.

HMAC uses two passes of hash computation. Before either pass, the secret key is used to derive two keys – inner and outer.

Editorial summary

“HMAC” enters the record as computer communications hash algorithm. Crown Archives preserves that source wording while asking what HMAC, computer and communications can confirm, complicate or overturn.

Editorial reviewA practical starting point whose main value is the path it opens into stronger specialist and primary sources. The current 225-word lead offers orientation but no explicit four-digit date, so chronology should not be assumed. The selected authority fields contribute no independent date. Its strongest next move is a source search built around HMAC, computer and communications.
Editorial analysis

Why this record matters

“HMAC” is worth following because a concise public description often conceals a longer documentary argument. Here, HMAC, computer and communications provides the most credible route into that argument.

Evidence profile

Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Sep 22, 2026. The linked authority identifier is Q1669397.

Critical limits

The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.

How to read it

Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.

Best used for
  • Subject orientation
  • Search vocabulary
  • Locating named sources
Verify next

The closest primary source, responsible institution and strongest cited specialist reference.

Three-step research path

  1. Establish the record: confirm the title “HMAC”, its source revision and the description used here.
  2. Expand the search: follow HMAC primary sources, HMAC archive and HMAC research across catalogues and specialist indexes.
  3. Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.

Questions for further research

  1. Which source most directly establishes the central claim about “HMAC”?
  2. Which cited source is closest to the event, object or claim?
  3. Which institution is responsible for the underlying evidence?
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Source & attribution

This entry incorporates text from “HMAC” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.