MAC unforgeability and what a forgery means
Research context
postgraduate concept · established · As of 2026-10-10
Existential unforgeability under chosen-message attack requires that an efficient adversary with a tagging oracle cannot produce a valid tag for a new message with more than negligible probability.
Key knowledge
Existential unforgeability under chosen-message attack requires that an efficient adversary with a tagging oracle cannot produce a valid tag for a new message with more than negligible probability. Strong unforgeability can additionally prohibit new valid tags on previously tagged messages. A MAC uses a shared secret and does not provide publicly verifiable attribution; replay protection requires a protocol freshness rule beyond the raw MAC game.
Conditions and scope
- Specify queried-message set, verification access, tag length, key distribution and ordinary versus strong forgery definition.
- Nonce, counter and domain-separation rules are protocol obligations; successful authentication need not imply confidentiality.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Author checked this English statement, displayed equation where present and stated hypotheses against these source locations: Encryption games chapters 2–3/9/12, authentication chapters 6–8, signatures chapter 13, reductions and identification/zero knowledge chapters 18–20. The check is bounded to the recorded claims; no complete proof reconstruction, software proof replay or universal literature completeness is claimed.
2026-10-10 · Author source-body/statement/equation/domain check, with graph associations scoped individually. Separate independent content/source/inventory review is required before branch closure.
Entry details
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