RFC 8747 Quiz (EN)

**Judgment point:** Separate the role of CWT confirmation key from nearby security functions and policy decisions. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: turning every CWT into a secure holder-bound token without an external proof is not the central purpose of RFC 8747. It can be nearby work, but it is not the decision this RFC primarily supports. - B: expressing proof-of-possession key information inside a CWT using CBOR-friendly confirmation semantics is the reason this RFC belongs in the review path. It drives checks on inputs, validation, and boundaries. - C: defining the authorization decision made after possession is proven is outside the RFC boundary. Higher-layer policy and adjacent protocol responsibilities still need separate text.

**Judgment point:** CWT confirmation key is a building block. Acceptance conditions, authorization, and deployment exceptions must still be explicit. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: which proof method and key confirmation formats are supported by the relying application is not decided by the RFC alone. The relying application must say what success means. - B: Skipping local acceptance policy can accept a valid object in the wrong context. That crosses the RFC boundary. - C: validate the CWT and then verify that the presenter proves possession of the referenced confirmation key is a boundary the implementation review must preserve. Source and scope mistakes cause false acceptance. - D: An RFC citation can be necessary, but deployment configuration, keys, trust, and failure handling are not automatic.

**Judgment point:** A profile is the contract that makes use of CWT confirmation key consistent across implementations. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: If input bytes and context are free-form, implementations verify different values. - B: Human-readable text is useful for explanation, but it is unstable as a validation input. Locale and wording changes break it. - C: encode the confirmation key or key reference in the CWT profile consistently with COSE and CBOR rules is required. Clear producer rules let verifiers evaluate the same object under the same assumptions.

**Judgment point:** Interoperability failures appear when the same wire data receives different processing meanings. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: validating COSE but failing to require a separate holder proof for the confirmation key shifts the validation target or meaning. Implementations can then disagree about success. - B: Limiting BCP 14 words to real requirements reduces ambiguity rather than creating it. - C: Documenting unsupported-extension behavior reduces implementation divergence.

**Judgment point:** CWT confirmation key needs validation against its defined inputs and scope, not just its delivery path. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: HTTPS protects transport, but it does not replace validation of CWT confirmation key. - B: validate the CWT and then verify that the presenter proves possession of the referenced confirmation key is the central step. It separates well-formed input from acceptable input. - C: A filename or path can be a routing hint, but it is not enough as identity or security proof.

**Judgment point:** A specification can define processing rules while still leaving acceptance policy outside the mechanism. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: CWT confirmation claim structure and holder-key identification methods is part of the mechanism RFC 8747 addresses directly. It is not the policy layer. - B: which proof method and key confirmation formats are supported by the relying application is an application or deployment acceptance condition. - C: Well-formed syntax and algorithm processing belong to the RFC-defined side. The meaning of success still needs policy. - D: whether key references are local, public, encrypted, or profile-defined is local policy. It should be written for the deployment and threat model.

**Judgment point:** A security review looks for false-acceptance paths, not just whether the mechanism is present. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: Performance can matter, but caching does not replace a security property. - B: A recent library helps, but local policy, inputs, and threat model still need review. - C: accepting the CWT as a bearer token even though it contains proof-of-possession semantics is the central failure mode. Attackers exploit this kind of context or trust shift.

**Judgment point:** Adjacent specifications are usually safer to read as layered responsibilities, not automatic replacements. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: RFC 8747 mirrors JWT proof-of-possession ideas for CWT and COSE-based token ecosystems preserves the responsibility split. - B: Obsoletion is explicit in RFC metadata and text. Nearby concepts do not automatically replace one another. - C: CWT confirmation key matters in protocol composition reviews. Treating it as unrelated hides boundaries.

**Judgment point:** Review questions should show whether implementers can reproduce the same success and failure boundary. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: Naming inputs, context, validation rules, and rejection behavior directly reduces implementation differences. - B: An RFC number does not define local semantics by itself. A profile or policy must fill the gap. - C: Treating unknown values as success can accept extensions or attacker input incorrectly. - D: when a constrained-device token must be bound to a key controlled by the presenter is a real review setting. Fixing success conditions there reduces misuse.

**Judgment point:** Validation failure is a signal to stop using that input as evidence for the decision. **Related keywords:** - **cnf**: Confirmation claim - **COSE key**: CBOR/COSE key representation - **holder proof**: Evidence of key possession **Options:** - A: Downgrading to a warning creates fail-open behavior. Attacker-controlled input can enter the success path. - B: Treating the result as unusable for that decision is safe. If fallback exists, it needs explicit policy. - C: Authorization is important, but it does not automatically repair broken validation input.