Stdlib module crypto/hmac.vitl

Overview

`crypto/hmac.vitl` is a public stdlib surface inside the `crypto` family. It should be read as one focused slice of the broader family responsibility: Hashing, HMAC, randomness, key derivation, symmetric primitives, and asymmetric primitives.

Purpose

This file should be chosen because of responsibility, not because its name “sounds close enough”. Inside the crypto family, it carries one focused part of the contract and keeps that responsibility separate from neighboring concerns.

• A package manifest can be serialized first, then hashed, then optionally signed.
• A token flow can derive a key in one boundary and use it in another without mixing concerns.

Taxonomy

Think of this page as a generated encyclopedia entry rather than a hand-written tutorial. The goal is to show what kind of module this is, how dense it is, and what reading strategy makes sense before depending on it.

• Medium procedure surface: this file groups several related operations behind one namespace.
• Owns domain vocabulary: the module declares data shapes in addition to executable helpers, so its types are part of the contract.
• Minimal top-level dependencies: the module reads as mostly self-contained from its opening declarations.

Implementation profile

This profile is inferred directly from the source text. It does not replace reading the file, but it tells you quickly whether the module is mostly declarative, loop-heavy, branch-heavy, or organized around many small exits.

Top-level API inventory

Imported surfaces

This file does not advertise a top-level `use` surface in its opening declarations. That often means it is either self-contained or an aggregation layer.

Position in family

This file is module 5 of 9 in the crypto family when ordered by path. By procedure count it ranks 8, and by line count it ranks 8. Those ranks are useful as rough signals of breadth, not as quality judgments.

Declaration map

The declaration map turns raw source into a scan-friendly catalog. It is useful when the file is large enough that a reader wants to orient by kinds of surfaces first.

The table is exhaustive for top-level declarations of the selected kinds. This file declares 11 matching surfaces.

Representative signatures

These signatures are shown in source order so the page keeps the feel of a reference manual, not just a keyword cloud.

• form HMAC { (line 9)
• form HMACManifest { (line 13)
• proc hmac_new() -> int { (line 17)
• proc hmac_update() -> int { (line 21)
• proc hmac_final() -> int { (line 25)
• proc hmac_final_hex() -> int { (line 29)
• proc hmac_version() -> int { (line 33)
• proc hmac_ready() -> int { (line 37)
• proc hmac_manifest() -> int { (line 41)
• proc hmac_selftest() -> int { (line 45)

How to use this module

Start by reading the file as an ownership boundary. Ask three questions: what enters this module, what stable types or procedures it exports, and what adjacent module should stay outside of it.

1. Read space and top-level imports first so the ownership boundary of crypto/hmac.vitl is explicit.
2. Read declared forms and picks before algorithms so the data vocabulary is stable in your head.
3. Traverse procedures in source order; the early helpers usually explain the naming and numeric conventions used later.
4. Only after that compare neighbor modules, because the right boundary choice matters more than memorizing one helper name.

User example

This example is generated from the actual stdlib module surface. Its job is not to be the smallest snippet possible; its job is to show a realistic consumer-shaped file that exercises the module and mirrors the language keywords the module itself relies on.

space demo/crypto_hmac
form UserReport {
  label: string,
  ready: bool
}
proc run_example() -> UserReport {
    give UserReport { label: "ok", ready: ready }
}

Keyword coverage

This table makes the “all keywords of the module” requirement auditable. It compares the detected Vitte keywords in the source file with the generated consumer example above.

The generated snippet exercises every detected Vitte keyword used by this module.

Source shape

space vitte/stdlib_checked/crypto_hmac
form HMAC {
  value: int
}
form HMACManifest {
  value: int
}
proc hmac_new() -> int {
  give 0
}

The excerpt is not meant to replace the file. It exists to make the module recognizable at first glance, the same way a Wikipedia infobox helps the reader orient before reading the whole article.

Source landmarks

Large files are easier to retain when they have visible landmarks. When the source contains explicit section banners, they are surfaced here; otherwise the first major declarations are used as anchors.

• Line 1: space vitte/stdlib_checked/crypto_hmac
• Line 9: form HMAC {
• Line 13: form HMACManifest {
• Line 17: proc hmac_new() -> int {
• Line 21: proc hmac_update() -> int {
• Line 25: proc hmac_final() -> int {
• Line 29: proc hmac_final_hex() -> int {
• Line 33: proc hmac_version() -> int {

Source organization

When a file carries its own internal chaptering, those chapters usually reveal the intended reading order better than a flat symbol list. This section reconstructs that organization from the source itself.

Complete API catalog

This catalog is the exhaustive file-level index for the module. It is intentionally closer to a generated encyclopedia appendix than to a tutorial summary.

Data surfaces

Procedures

Integration boundaries

Within crypto, this file should remain focused. If a future helper changes the host boundary, scheduling boundary, or data-shape boundary, it probably belongs in a neighbor module instead of being added here by convenience.

• Family responsibility: Hashing, HMAC, randomness, key derivation, symmetric primitives, and asymmetric primitives.
• Family architecture role: Use `crypto` when integrity, secrecy, or key management is the feature. This family should never be presented as generic formatting or utility code.

Composition guidance

Choose this module when

• Choose crypto/hmac.vitl when the main question is owned by this module rather than by transport, storage, orchestration, or user-interface code.
• A package manifest can be serialized first, then hashed, then optionally signed.
• A token flow can derive a key in one boundary and use it in another without mixing concerns.

Pause before extending it when

• Avoid extending this file when the new helper mostly changes the boundary to host I/O, runtime coordination, or foreign integration instead of staying inside crypto.
• Check nearby modules such as crypto/asymmetric.vitl, crypto/hash.vitl, crypto/hashing.vitl before adding convenience wrappers here.

Relationship table

This table keeps the page closer to a real encyclopedia entry: a module is easier to understand when compared with its nearest alternatives in the same family.

Neighbor modules

• crypto/asymmetric.vitl
• crypto/hash.vitl
• crypto/hashing.vitl
• crypto/keyderivation.vitl
• crypto/random.vitl
• crypto/symmetric.vitl
• crypto/utils.vitl
• crypto.vitl