Sign only declared HTTP components with complete signature metadata

Use this document to connect an official requirement or behavior to observable evidence: Sign only declared HTTP components with complete signature metadata. Only the official source and traced locations below supply facts. Confirm applicability before acting.

Source fact:

The official RFC 9421 — HTTP Message Signatures from RFC Editor / Internet Engineering Task Force supports the following bounded statements:

• A signer fixes an ordered set of covered component identifiers, MUST NOT change that order for the signature’s lifetime, and then creates the signature base from those components in order. The research record locates this support at Sections 3.1 (Creating a Signature) and 2.5 (Creating the Signature Base).
• The signature-parameters component is REQUIRED as the last signature-base line and carries the ordered covered-component set plus metadata such as created, expires, nonce, algorithm, key identifier, and tag. The research record locates this support at Section 2.3 (Signature Parameters).
• Every HTTP message signature MUST have matching, unique labels in both Signature-Input and Signature; Signature-Input identifies covered components and metadata, while Signature carries the signature value. The research record locates this support at Section 4 (Including a Message Signature in a Message).

The source support ends with the statements listed above. Use them to examine clients, origin services, intermediaries, caches, proxies, gateways, protocol versions, and security-policy enforcement points in the applicable environment, not to imply a wider guarantee.

What the source does not establish

This RFC evidence supports only the named web or transport decision; it does not prove browser, intermediary, library, or service compatibility. It does not establish a deployment’s current state, authorize a production change, prove compliance, or show that DNS, certificates, identity providers, time, content delivery, network paths, and application ownership are healthy. Documented options are review inputs, not universal mandates.

Applicability questions

• For source statement 1 at Sections 3.1 (Creating a Signature) and 2.5 (Creating the Signature Base), which observable configuration, record, or test can confirm applicability here?
• For source statement 2 at Section 2.3 (Signature Parameters), which observable configuration, record, or test can confirm applicability here?
• For source statement 3 at Section 4 (Including a Message Signature in a Message), which observable configuration, record, or test can confirm applicability here?
• What inventory proves which parts of clients, origin services, intermediaries, caches, proxies, gateways, protocol versions, and security-policy enforcement points are in and out of scope?
• Which condition in DNS, certificates, identity providers, time, content delivery, network paths, and application ownership must be healthy before evidence is trustworthy?
• What result would disprove the working assumption and return the issue to the owner?

DSE recommendation:

DSE recommends using the cited source as the evidence anchor for this decision. Make the source, asset scope, owner, and expected outcome explicit in the review record. Record the source location, examined part of clients, origin services, intermediaries, caches, proxies, gateways, protocol versions, and security-policy enforcement points, observed and expected states, owner, and reason for deviation.

An implementation decision needs an owner, approved window, prechecks, observable outcome, stop authority, and rollback path. Validate DNS, certificates, identity providers, time, content delivery, network paths, and application ownership before and after the test, and store only sanitized operational evidence.

Verification and evidence

Tie each conclusion back to Sections 3.1 (Creating a Signature) and 2.5 (Creating the Signature Base); Section 2.3 (Signature Parameters); Section 4 (Including a Message Signature in a Message) and to observable material such as request and response captures, negotiated protocol details, headers, cache behavior, certificate state, and server or proxy logs. Preserve provenance and stable identifiers without copying secrets into the evidence set.

Preserve both successful and failed observations, along with approval and rollback evidence. Avoid uncontrolled production experiments. Assign an expiry or event-driven recheck so the conclusion is not treated as permanent.

Official references

• RFC 9421 — HTTP Message Signatures — RFC Editor / Internet Engineering Task Force