RFC 9530 Quiz (EN)

**Judgment point:** Separate the role of HTTP Digest Fields from nearby security functions and policy decisions. **Related keywords:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **Options:** - A: authenticating the sender without a signature, MAC, or secure channel is not the central purpose of RFC 9530. It can be nearby work, but it is not the decision this RFC primarily supports. - B: carrying digests of HTTP content in fields so recipients can detect representation-data changes is the reason this RFC belongs in the review path. It drives checks on inputs, validation, and boundaries. - C: hashing arbitrary application state that is not the selected HTTP content is outside the RFC boundary. Higher-layer policy and adjacent protocol responsibilities still need separate text.

**Judgment point:** HTTP Digest Fields is a building block. Acceptance conditions, authorization, and deployment exceptions must still be explicit. **Related keywords:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **Options:** - A: which digest algorithms and failure behavior are required by the application or signature profile 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: recompute the digest over the correct content or representation data and compare it before relying on the field 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 HTTP Digest Fields consistent across implementations. **Related keywords:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **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: state which digest field is used and compute it over the bytes defined by HTTP semantics 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:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **Options:** - A: computing a digest over one representation while recipients verify another transformed representation 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:** HTTP Digest Fields needs validation against its defined inputs and scope, not just its delivery path. **Related keywords:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **Options:** - A: HTTPS protects transport, but it does not replace validation of HTTP Digest Fields. - B: recompute the digest over the correct content or representation data and compare it before relying on the field 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:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **Options:** - A: Content-Digest, Repr-Digest, digest algorithms, and the selected content bytes is part of the mechanism RFC 9530 addresses directly. It is not the policy layer. - B: which digest algorithms and failure behavior are required by the application or signature profile 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 trailers, transformations, or content codings are allowed 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:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **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: treating an unkeyed digest as sender authentication or tamper resistance against an active attacker by itself 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:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **Options:** - A: HTTP Message Signatures can sign Digest Fields, giving the digest sender-authenticated context when coverage is configured preserves the responsibility split. - B: Obsoletion is explicit in RFC metadata and text. Nearby concepts do not automatically replace one another. - C: HTTP Digest Fields 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:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **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 an API wants a stable integrity check for request or response content that may also be signed 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:** - **Content-Digest**: Digest over selected content data - **Repr-Digest**: Digest over representation data - **unkeyed digest**: Hash result without a secret key **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.