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Message authentication code

keyed hash function used to protect a message's integrity and authenticity

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General referenceInterpretive dossier study · Crown Archives visual atlas
Record originEnglish Wikipedia
Text licenseCC BY-SA 4.0
Source revisionJun 26, 2026
Entity authorityQ1052621 ↗
Source-derived summary

In cryptography, a message authentication code (MAC), sometimes known as an authentication tag, is a short piece of information used for authenticating and integrity-checking a message. In other words, it is used to confirm that the message came from the stated sender (its authenticity) and has not been changed (its integrity). The MAC value allows verifiers (who also possess a secret key) to detect any changes to the message content.

Terminology

The term message integrity code (MIC) is frequently substituted for the term MAC, especially in communications to distinguish it from the use of the latter as Media Access Control (as in MAC address). However, some authors use MIC to refer to a message digest, which aims only to uniquely but opaquely identify a single message. As such, it is recommended to avoid the term message integrity code (MIC), and instead use checksum, error detection code, hash, keyed hash, message authentication code, or protected checksum.

Definitions

Informally, a message authentication code system consists of three algorithms:

A key generation algorithm selects a key from the key space uniformly at random.

A MAC generation algorithm efficiently returns a tag given the key and the message.

A verifying algorithm efficiently verifies the authenticity of the message given the same key and the tag. That is, return accepted when the message and tag are not tampered with or forged, and otherwise return rejected.

Editorial summary

The public source identifies “Message authentication code” as keyed hash function used to protect a message's integrity and authenticity. This brief keeps that definition visible, then builds a research path around Message, authentication and code.

Editorial reviewA practical starting point whose main value is the path it opens into stronger specialist and primary sources. The current 230-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 value is orientation rather than verdict, with Message, authentication and code providing the first useful test.
Editorial analysis

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A short description can identify a subject without explaining its stakes. For “Message authentication code”, the useful work is to connect “keyed hash function used to protect a message's integrity and authenticity” to the records capable of establishing context and consequence.

Evidence profile

The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Jun 26, 2026. The linked authority identifier is Q1052621.

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.

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Source & attribution

This entry incorporates text from “Message authentication code” 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.