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MAC + SKE ⇒ CCA Security

MAC together with SKE implies CCA Security.

Statement

Migrated verbatim from symmetric-key-encryption § Other results:

  • CCA-secure SKE can be built from OWF: combine a CPA-secure SKE with a MAC using the encrypt-then-MAC paradigm

Migrated verbatim from symmetric-key-encryption § Other results:

  • CPA-secure SKE can be boosted to CCA-secure SKE using a MAC

Notes

source: folklore: the claim carried no citation on the page it was migrated from, and none was invented.

class: unstated: no citing page says which notion of reduction is meant. Recording a class the wiki does not state would add a claim.

This relation is stated on 2 pages; the statements above are all of them.

Class disagrees across pages: [object Object]

Recorded during migration and not fixed — these are claims about the source text, not changes to it:

  • MISSING CITATION: encrypt-then-MAC is Bellare-Namprempre (BN00), with no reference page and no folklore label, which the page’s own citation policy requires.
  • The MAC must be strongly unforgeable for encrypt-then-MAC to give CCA security — a condition neither the bullet nor the node captures.
  • ‘cca-secure-symmetric-key-encryption’ has no node, so the edge would collapse to SKE ⇒ SKE.
  • MISSING CITATION entirely — encrypt-then-MAC is BN00 (Bellare-Namprempre); no citation and no folklore label, which the page’s own citation policy requires.
  • COMPOSITE and CONJUNCTIVE at once: OWF ⇒ CPA-SKE, OWF ⇒ MAC, then {CPA-SKE, MAC} ⇒ CCA-SKE.
  • ‘OWF’ here has no wikilink at all (line 125 links it to hash-function; line 126 leaves it bare) — inconsistent within four lines.
  • The conclusion is a security level of SKE, not a distinct object; the graph needs security-level-qualified nodes or this edge becomes SKE ⇒ SKE.
  • REPAIR PATCH: Arity sweep. Wiki L126: “CCA-secure SKE can be built from OWF: combine a CPA-secure SKE with a [[message-authentication-code|MAC]] using the encrypt-then-MAC paradigm”. The critic cites this record as a calibration example of CORRECT modelling and it is — except for the flag: the top-level edge has ONE hypothesis (OWF) and the genuine conjunction {SKE, MAC} lives in splitInto[2], where it belongs. Repair: conjunctive:false at top level. Sub-edges need their own conjunctive flag (schema defect 6.1) or this conjunction is lost on split.
  • DUPLICATE: this is the third link of the line-126 bullet restated as its own bullet; the page asserts the same reduction twice in consecutive lines.
  • MISSING CITATION (BN00).
  • Genuinely conjunctive {CPA-SKE, MAC} ⇒ CCA-SKE, and the strongest single example on this page of why conjunction must be representable.

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