ssri 12.0.0: fromHex

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify ssri.fromHex in pkg:npm/ssri@12.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/ssri@12.0.0
Demonstrate these symbols/APIs:
  - ssri.fromHex

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:b7b8e4c73ef8980ad346e7b3cb9128412ee458bd3e66b6454b75fd6a1d7f8d0e","contract":["ssri.fromHex(hexDigest, algorithm) converts a hex string into an Integrity object with base64-encoded Hash entry","ssri.fromHex(hexDigest, algorithm, { single: true }) returns a single Hash object directly","ssri.fromHex(hexDigest, algorithm, { options }) attaches SRI option tokens to the generated hash metadata","Integrity produced by ssri.fromHex round-trips with hexDigest() and validates data with ssri.checkData"],"goal":"verify ssri.fromHex in pkg:npm/ssri@12.0.0","kind":"HOW","packages":["pkg:npm/ssri@12.0.0"],"schemaVersion":1,"symbols":["ssri.fromHex"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/ssri@12.0.0"],"schemaVersion":1,"subject":"pkg:npm/ssri@12.0.0","symbols":["ssri.fromHex"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-ssri-fromhex",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-ssri-fromhex",
      "version": "1.0.0",
      "dependencies": {
        "ssri": "12.0.0"
      }
    },
    "node_modules/minipass": {
      "version": "7.1.3",
      "resolved": "https://registry.npmjs.org/minipass/-/minipass-7.1.3.tgz",
      "integrity": "sha512-tEBHqDnIoM/1rXME1zgka9g6Q2lcoCkxHLuc7ODJ5BxbP5d4c2Z5cGgtXAku59200Cx7diuHTOYfSBD8n6mm8A==",
      "license": "BlueOak-1.0.0",
      "engines": {
        "node": ">=16 || 14 >=14.17"
      }
    },
    "node_modules/ssri": {
      "version": "12.0.0",
      "resolved": "https://registry.npmjs.org/ssri/-/ssri-12.0.0.tgz",
      "integrity": "sha512-S7iGNosepx9RadX82oimUkvr0Ct7IjJbEbs4mJcTxst8um95J3sDYU1RBEOvdu6oL1Wek2ODI5i4MAw+dZ6cAQ==",
      "license": "ISC",
      "dependencies": {
        "minipass": "^7.0.3"
      },
      "engines": {
        "node": "^18.17.0 || >=20.5.0"
      }
    }
  }
}

{
  "name": "sample-ssri-fromhex",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "ssri": "12.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify ssri.fromHex in pkg:npm/ssri@12.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/ssri@12.0.0"
  ],
  "symbols": [
    "ssri.fromHex"
  ]
}

import assert from 'node:assert/strict'
import { createHash } from 'node:crypto'
import * as ssri from 'ssri'

const payload = Buffer.from('verify ssri.fromHex contract payload')
const sha256Hex = createHash('sha256').update(payload).digest('hex')
const sha512Hex = createHash('sha512').update(payload).digest('hex')
const sha256Base64 = Buffer.from(sha256Hex, 'hex').toString('base64')

// 1. Default ssri.fromHex returns an Integrity object containing a Hash entry for the algorithm
const integrity = ssri.fromHex(sha256Hex, 'sha256')
assert.equal(integrity.isIntegrity, true)
assert.equal(Array.isArray(integrity.sha256), true)
assert.equal(integrity.sha256.length, 1)
assert.equal(integrity.sha256[0].isHash, true)
assert.equal(integrity.sha256[0].algorithm, 'sha256')
assert.equal(integrity.sha256[0].digest, sha256Base64)
assert.deepEqual(integrity.sha256[0].options, [])
assert.equal(integrity.toString(), `sha256-${sha256Base64}`)
assert.equal(integrity.hexDigest(), sha256Hex)

// 2. ssri.fromHex with single: true returns a single Hash instance directly
const singleHash = ssri.fromHex(sha512Hex, 'sha512', { single: true })
assert.equal(singleHash.isHash, true)
assert.equal(singleHash.isIntegrity, undefined)
assert.equal(singleHash.algorithm, 'sha512')
assert.equal(singleHash.hexDigest(), sha512Hex)

// 3. ssri.fromHex with options attaches SRI options to the resulting metadata
const withOpts = ssri.fromHex(sha256Hex, 'sha256', {
  options: ['optA', 'optB'],
})
assert.deepEqual(withOpts.sha256[0].options, ['optA', 'optB'])
assert.equal(withOpts.toString(), `sha256-${sha256Base64}?optA?optB`)

// 4. Integrity produced by ssri.fromHex validates matching data via ssri.checkData
const matched = ssri.checkData(payload, integrity)
assert.equal(matched.algorithm, 'sha256')
assert.equal(matched.hexDigest(), sha256Hex)