RFC 9052 Quiz (EN)

**Judgment point:** Separate the role of COSE security structure from nearby security functions and policy decisions. **Related keywords:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **Options:** - A: deciding whether the signer or encrypted content is trusted for a business action is not the central purpose of RFC 9052. It can be nearby work, but it is not the decision this RFC primarily supports. - B: protecting CBOR data with signature, MAC, or encryption structures and explicit protected parameters is the reason this RFC belongs in the review path. It drives checks on inputs, validation, and boundaries. - C: making unprotected header parameters integrity protected by convention is outside the RFC boundary. Higher-layer policy and adjacent protocol responsibilities still need separate text.

**Judgment point:** COSE security structure is a building block. Acceptance conditions, authorization, and deployment exceptions must still be explicit. **Related keywords:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **Options:** - A: which keys, algorithms, recipients, countersignatures, and payload meanings are acceptable 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: verify protected headers, algorithm policy, key selection, payload coverage, and signature or MAC result before accepting content 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 COSE security structure consistent across implementations. **Related keywords:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **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: place security-critical parameters in protected headers and define the application profile for keys and algorithms 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:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **Options:** - A: letting an attacker move a parameter from protected to unprotected headers without changing acceptance 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:** COSE security structure needs validation against its defined inputs and scope, not just its delivery path. **Related keywords:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **Options:** - A: HTTPS protects transport, but it does not replace validation of COSE security structure. - B: verify protected headers, algorithm policy, key selection, payload coverage, and signature or MAC result before accepting content 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:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **Options:** - A: COSE_Sign, COSE_Mac, COSE_Encrypt structures, protected headers, payload, and algorithm parameters is part of the mechanism RFC 9052 addresses directly. It is not the policy layer. - B: which keys, algorithms, recipients, countersignatures, and payload meanings are acceptable 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 payloads are detached, countersigned, encrypted, or nested 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:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **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: trusting unprotected headers or algorithm hints before enforcing local key and algorithm policy 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:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **Options:** - A: CWT commonly uses COSE protection, while COSE itself is the generic CBOR security container preserves the responsibility split. - B: Obsoletion is explicit in RFC metadata and text. Nearby concepts do not automatically replace one another. - C: COSE security structure 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:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **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 CBOR tokens, attestation evidence, or compact messages need signature, MAC, or encryption 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:** - **protected header**: Integrity-protected parameter area - **COSE_Sign**: COSE signing structure - **algorithm policy**: Local algorithm acceptance rule **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.