asn1js 3.0.10: Sequence

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 asn1js.Sequence in pkg:npm/asn1js@3.0.10
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/asn1js@3.0.10
Demonstrate these symbols/APIs:
  - asn1js.Sequence
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:sha256:9f0747b00e9c6f9ef68b93fd7918f443c329b5d866125e3312af7b2b1cf028c4","constraints":{"executionContext":"node"},"contract":["Sequence instantiates a universal constructed ASN.1 element with tag number 16","Sequence encodes ordered child elements and nested sequences to BER ArrayBuffer","fromBER parses BER buffers into Sequence instances preserving child element types and order","Sequence defines structured schemas with optional elements for verifySchema validation"],"goal":"verify asn1js.Sequence in pkg:npm/asn1js@3.0.10","kind":"HOW","packages":["pkg:npm/asn1js@3.0.10"],"schemaVersion":1,"symbols":["asn1js.Sequence"]},"contractCommand":["node","test/contract.js"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/asn1js@3.0.10"],"schemaVersion":1,"subject":"pkg:npm/asn1js@3.0.10","symbols":["asn1js.Sequence"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-asn1js-sequence",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-asn1js-sequence",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "asn1js": "3.0.10"
      }
    },
    "node_modules/asn1js": {
      "version": "3.0.10",
      "resolved": "https://registry.npmjs.org/asn1js/-/asn1js-3.0.10.tgz",
      "integrity": "sha512-S2s3aOytiKdFRdulw2qPE51MzjzVOisppcVv7jVFR+Kw0kxwvFrDcYA0h7Ndqbmj0HkMIXYWaoj7fli8kgx1eg==",
      "license": "BSD-3-Clause",
      "dependencies": {
        "pvtsutils": "^1.3.6",
        "pvutils": "^1.1.5",
        "tslib": "^2.8.1"
      },
      "engines": {
        "node": ">=12.0.0"
      }
    },
    "node_modules/pvtsutils": {
      "version": "1.3.6",
      "resolved": "https://registry.npmjs.org/pvtsutils/-/pvtsutils-1.3.6.tgz",
      "integrity": "sha512-PLgQXQ6H2FWCaeRak8vvk1GW462lMxB5s3Jm673N82zI4vqtVUPuZdffdZbPDFRoU8kAhItWFtPCWiPpp4/EDg==",
      "license": "MIT",
      "dependencies": {
        "tslib": "^2.8.1"
      }
    },
    "node_modules/pvutils": {
      "version": "1.2.0",
      "resolved": "https://registry.npmjs.org/pvutils/-/pvutils-1.2.0.tgz",
      "integrity": "sha512-BbubeCEyTuQjVMakvJQ/Sxbc93F2pwmbsxONT/ZRrwU7Ua38d8unYTwXpTVLAKJ4BDuH9IGztCjQcd/N/39Dvg==",
      "license": "MIT",
      "engines": {
        "node": ">=16.0.0"
      }
    },
    "node_modules/tslib": {
      "version": "2.8.1",
      "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
      "integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
      "license": "0BSD"
    }
  }
}

{
  "name": "sample-asn1js-sequence",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification sample for asn1js.Sequence",
  "main": "src/index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "asn1js": "3.0.10"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify asn1js.Sequence in pkg:npm/asn1js@3.0.10",
  "kind": "HOW",
  "packages": [
    "pkg:npm/asn1js@3.0.10"
  ],
  "symbols": [
    "asn1js.Sequence"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

'use strict';

const asn1js = require('asn1js');

/**
 * Creates an empty ASN.1 Sequence.
 * @returns {asn1js.Sequence}
 */
function createEmptySequence() {
  return new asn1js.Sequence();
}

/**
 * Creates an ASN.1 Sequence with the provided child elements.
 * @param {asn1js.BaseBlock[]} elements
 * @returns {asn1js.Sequence}
 */
function createSequence(elements) {
  return new asn1js.Sequence({
    value: elements
  });
}

/**
 * Creates an ASN.1 Sequence containing child elements and an embedded nested Sequence.
 * @param {asn1js.BaseBlock[]} parentElements
 * @param {asn1js.BaseBlock[]} childElements
 * @returns {asn1js.Sequence}
 */
function createNestedSequence(parentElements, childElements) {
  const inner = new asn1js.Sequence({
    value: childElements
  });
  return new asn1js.Sequence({
    value: [...parentElements, inner]
  });
}

/**
 * Encodes an ASN.1 Sequence to BER format ArrayBuffer.
 * @param {asn1js.Sequence} sequence
 * @returns {ArrayBuffer}
 */
function encodeSequence(sequence) {
  return sequence.toBER();
}

/**
 * Decodes a BER buffer and ensures the root is an ASN.1 Sequence.
 * @param {ArrayBuffer|Uint8Array} buffer
 * @returns {{ offset: number, result: asn1js.Sequence }}
 */
function decodeSequence(buffer) {
  const decoded = asn1js.fromBER(buffer);
  if (!(decoded.result instanceof asn1js.Sequence)) {
    throw new TypeError('Decoded ASN.1 structure is not a Sequence');
  }
  return decoded;
}

/**
 * Creates a Sequence schema block for schema verification.
 * @param {string} name
 * @param {asn1js.BaseBlock[]} elementSchemas
 * @param {boolean} [optional=false]
 * @returns {asn1js.Sequence}
 */
function createSequenceSchema(name, elementSchemas, optional = false) {
  return new asn1js.Sequence({
    name,
    optional,
    value: elementSchemas
  });
}

module.exports = {
  createEmptySequence,
  createSequence,
  createNestedSequence,
  encodeSequence,
  decodeSequence,
  createSequenceSchema,
  asn1js
};

'use strict';

const assert = require('node:assert');
const asn1js = require('asn1js');
const {
  createEmptySequence,
  createSequence,
  createNestedSequence,
  encodeSequence,
  decodeSequence,
  createSequenceSchema
} = require('../src/index.js');

// 1. Sequence instantiates a universal constructed ASN.1 element with tag number 16
const emptySeq = createEmptySequence();
assert(emptySeq instanceof asn1js.Sequence, 'Must be instance of Sequence');
assert.strictEqual(asn1js.Sequence.NAME, 'SEQUENCE', 'Sequence.NAME must be SEQUENCE');
assert.strictEqual(emptySeq.idBlock.tagClass, 1, 'Universal class tagClass is 1');
assert.strictEqual(emptySeq.idBlock.tagNumber, 16, 'SEQUENCE tagNumber is 16');
assert.strictEqual(emptySeq.idBlock.isConstructed, true, 'SEQUENCE must be constructed');
assert.strictEqual(emptySeq.valueBlock.value.length, 0, 'Empty sequence has 0 children');

// 2. Sequence encodes ordered child elements and nested sequences to BER ArrayBuffer
const emptyBer = encodeSequence(emptySeq);
assert(emptyBer instanceof ArrayBuffer, 'toBER must return ArrayBuffer');
const emptyBytes = new Uint8Array(emptyBer);
assert.strictEqual(emptyBytes.length, 2, 'Empty sequence BER length is 2 bytes');
assert.strictEqual(emptyBytes[0], 0x30, 'Tag 0x30 for constructed Sequence');
assert.strictEqual(emptyBytes[1], 0x00, 'Length 0 for empty Sequence');

const nestedSeq = createNestedSequence(
  [new asn1js.Utf8String({ value: 'parent-item' })],
  [new asn1js.Integer({ value: 12345 }), new asn1js.Boolean({ value: true })]
);
const nestedBer = encodeSequence(nestedSeq);
assert(nestedBer.byteLength > 2, 'Nested sequence BER has positive content length');

// 3. fromBER parses BER buffers into Sequence instances preserving child element types and order
const decodedEmpty = decodeSequence(emptyBer);
assert.strictEqual(decodedEmpty.offset, emptyBer.byteLength, 'Decoded empty consumes full buffer');
assert(decodedEmpty.result instanceof asn1js.Sequence, 'Decoded result is Sequence');
assert.strictEqual(decodedEmpty.result.valueBlock.value.length, 0, 'Decoded empty has 0 children');

const decodedNested = decodeSequence(nestedBer);
assert.strictEqual(decodedNested.offset, nestedBer.byteLength, 'Decoded nested consumes full buffer');
assert(decodedNested.result instanceof asn1js.Sequence, 'Decoded root is Sequence');
assert.strictEqual(decodedNested.result.valueBlock.value.length, 2, 'Decoded root has 2 children');

const child0 = decodedNested.result.valueBlock.value[0];
assert(child0 instanceof asn1js.Utf8String, 'First child is Utf8String');
assert.strictEqual(child0.valueBlock.value, 'parent-item', 'First child value matches');

const child1 = decodedNested.result.valueBlock.value[1];
assert(child1 instanceof asn1js.Sequence, 'Second child is nested Sequence');
assert.strictEqual(child1.valueBlock.value.length, 2, 'Nested sequence has 2 elements');

const inner0 = child1.valueBlock.value[0];
assert(inner0 instanceof asn1js.Integer, 'Inner child 0 is Integer');
assert.strictEqual(inner0.valueBlock.valueDec, 12345, 'Inner integer matches');

const inner1 = child1.valueBlock.value[1];
assert(inner1 instanceof asn1js.Boolean, 'Inner child 1 is Boolean');
assert.strictEqual(inner1.valueBlock.value, true, 'Inner boolean matches');

// 4. Sequence defines structured schemas with optional elements for verifySchema validation
const schema = createSequenceSchema('Root', [
  new asn1js.Utf8String({ name: 'title' }),
  createSequenceSchema('OptionalInner', [
    new asn1js.Integer({ name: 'code' }),
    new asn1js.Boolean({ name: 'flag' })
  ], true)
]);

const validNested = encodeSequence(createNestedSequence(
  [new asn1js.Utf8String({ value: 'title' })],
  [new asn1js.Integer({ value: 99 }), new asn1js.Boolean({ value: false })]
));
const resValid = asn1js.verifySchema(validNested, schema);
assert.strictEqual(resValid.verified, true, 'Schema verification succeeds with optional sequence present');
assert.strictEqual(resValid.result.title.valueBlock.value, 'title');
assert.strictEqual(resValid.result.code.valueBlock.valueDec, 99);

const validWithoutOptional = encodeSequence(createSequence([
  new asn1js.Utf8String({ value: 'title' })
]));
const resOmitted = asn1js.verifySchema(validWithoutOptional, schema);
assert.strictEqual(resOmitted.verified, true, 'Schema verification succeeds when optional sequence is omitted');

const invalidMismatch = encodeSequence(createSequence([
  new asn1js.Integer({ value: 123 })
]));
const resInvalid = asn1js.verifySchema(invalidMismatch, schema);
assert.strictEqual(resInvalid.verified, false, 'Schema verification fails on type mismatch');

console.log('Contract tests passed successfully.');