How deeply does Real-World Cryptography cover GMAC?

Builds the tag from GHASH and AES-CTR, including block processing and nonce-reuse consequences.

GMAC

GMAC is a message authentication code built from the GHASH keyed hash and AES-CTR encryption of its output.

GMAC is a message authentication code: it turns input into an authentication tag so a receiver can detect tampering. It combines GHASH with AES-CTR, using GHASH to process the input and AES-CTR to encrypt the resulting digest. section 4.5.2

Nonce reuse warning

AES-CTR requires a unique nonce. Reusing one creates the same keystream, allowing two ciphertexts to reveal the XOR of their plaintexts. section 4.5.2

How Real-World Cryptography covers it

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Related concepts

Galois/Counter Modeused by · Galois/Counter Mode is an authenticated-encryption mode that combines counter-mode encryption with authentication of ciphertext and associated data.
GCMPused by · GCMP is a wireless data-protection protocol that combines AES counter-mode encryption with GMAC integrity protection.
GHASHuses · GHASH is a keyed almost-XOR-universal hash function used by GCM to authenticate block-aligned input.

This explainer was generated by Manning's knowledge graph from the text of Real-World Cryptography. The section links point to the parts of the book it draws on.