SRCmail/lib/smime-ca/__tests__/local-dev-provider.test.ts

import { describe, expect, it, beforeEach, afterEach } from 'vitest';
import { mkdtemp, rm } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import path from 'node:path';
import { webcrypto } from 'node:crypto';
import * as asn1js from 'asn1js';
import * as pkijs from 'pkijs';
import { LocalDevCaProvider } from '../local-dev-provider';

function pemToBer(pem: string): ArrayBuffer {
  const b64 = pem.replace(/-----BEGIN[^-]+-----/, '').replace(/-----END[^-]+-----/, '').replace(/\s+/g, '');
  const bin = Buffer.from(b64, 'base64');
  return bin.buffer.slice(bin.byteOffset, bin.byteOffset + bin.byteLength);
}

function berToPem(der: ArrayBuffer, label: string): string {
  const b64 = Buffer.from(der).toString('base64');
  const lines = b64.match(/.{1,64}/g) ?? [];
  return `-----BEGIN ${label}-----\n${lines.join('\n')}\n-----END ${label}-----`;
}

/** Builds a real, validly-self-signed CSR — the same shape a browser's
 *  WebCrypto-based plugin code would produce, just done here in Node so the
 *  test needs no browser. */
async function buildRealCsr(commonName: string): Promise<string> {
  const keys = await webcrypto.subtle.generateKey(
    { name: 'RSASSA-PKCS1-v1_5', modulusLength: 2048, publicExponent: new Uint8Array([1, 0, 1]), hash: 'SHA-256' },
    true,
    ['sign', 'verify'],
  ) as CryptoKeyPair;

  const csr = new pkijs.CertificationRequest();
  csr.version = 0;
  csr.subject.typesAndValues = [
    new pkijs.AttributeTypeAndValue({ type: '2.5.4.3', value: new asn1js.Utf8String({ value: commonName }) }),
  ];
  await csr.subjectPublicKeyInfo.importKey(keys.publicKey);
  await csr.sign(keys.privateKey, 'SHA-256');
  return berToPem(csr.toSchema().toBER(false), 'CERTIFICATE REQUEST');
}

describe('LocalDevCaProvider', () => {
  let stateDir: string;

  beforeEach(async () => {
    stateDir = await mkdtemp(path.join(tmpdir(), 'smime-dev-ca-test-'));
    process.env.ADMIN_STATE_DIR = stateDir;
  });

  afterEach(async () => {
    delete process.env.ADMIN_STATE_DIR;
    await rm(stateDir, { recursive: true, force: true });
  });

  it('issues a certificate signed by its own CA, honouring server-chosen addresses only', async () => {
    const provider = new LocalDevCaProvider();
    const csrPem = await buildRealCsr('CN the CSR asked for, should be ignored for SAN purposes');

    const issued = await provider.enroll({
      csrPem,
      addresses: ['alice@example.com', 'alice.alt@example.com'],
      commonName: 'Alice Example',
    });

    expect(issued.certificatePem).toContain('BEGIN CERTIFICATE');
    expect(issued.chainPem).toHaveLength(1);
    expect(issued.serialNumber).toMatch(/^[0-9a-f]+$/i);

    const leaf = pkijs.Certificate.fromBER(pemToBer(issued.certificatePem));
    const caCert = pkijs.Certificate.fromBER(pemToBer(issued.chainPem[0]));

    // Real cryptographic chain verification, not just "a string looks like a cert".
    const chainVerified = await leaf.verify(caCert);
    expect(chainVerified).toBe(true);

    // The certificate must assert exactly the server-provided addresses,
    // never anything from the CSR's own (ignored) subject. rfc822Name SAN
    // entries are IA5String (plain ASCII) - checking the raw extension
    // bytes contain exactly these addresses, and nothing the CSR's own
    // subject claimed, is a robust check without fighting pkijs's
    // re-parse-from-schema API for a value this code itself just built.
    const sanExt = leaf.extensions?.find((e) => e.extnID === '2.5.29.17');
    expect(sanExt).toBeDefined();
    const sanRaw = Buffer.from(sanExt!.extnValue.valueBlock.valueHexView).toString('latin1');
    expect(sanRaw).toContain('alice@example.com');
    expect(sanRaw).toContain('alice.alt@example.com');
    expect(sanRaw).not.toContain('CN the CSR asked for');

    // extKeyUsage must include emailProtection (OID 1.3.6.1.5.5.7.3.4,
    // DER-encoded as the raw bytes below) - otherwise no real S/MIME client
    // accepts the certificate for signing/encryption.
    const ekuExt = leaf.extensions?.find((e) => e.extnID === '2.5.29.37');
    expect(ekuExt).toBeDefined();
    const emailProtectionOidDer = Buffer.from([0x06, 0x08, 0x2b, 0x06, 0x01, 0x05, 0x05, 0x07, 0x03, 0x04]);
    expect(Buffer.from(ekuExt!.extnValue.valueBlock.valueHexView).includes(emailProtectionOidDer)).toBe(true);
  });

  it('rejects a CSR with a forged/mismatched signature', async () => {
    const provider = new LocalDevCaProvider();
    const validPem = await buildRealCsr('Whatever');
    // Corrupt one byte in the middle of the base64 body to break the signature
    // without breaking PEM framing.
    const lines = validPem.split('\n');
    const bodyIdx = Math.floor(lines.length / 2);
    lines[bodyIdx] = lines[bodyIdx].slice(0, -4) + (lines[bodyIdx].slice(-4) === 'AAAA' ? 'BBBB' : 'AAAA');
    const tamperedPem = lines.join('\n');

    await expect(
      provider.enroll({ csrPem: tamperedPem, addresses: ['x@example.com'], commonName: 'X' }),
    ).rejects.toThrow(/parsed|signature/i);
  });

  it('persists the same CA across calls (does not mint a new root every time)', async () => {
    const provider = new LocalDevCaProvider();
    const chain1 = await provider.getChain();
    const chain2 = await provider.getChain();
    expect(chain1[0]).toBe(chain2[0]);
  });

  it('records a revocation', async () => {
    const provider = new LocalDevCaProvider();
    const csrPem = await buildRealCsr('Bob');
    const issued = await provider.enroll({ csrPem, addresses: ['bob@example.com'], commonName: 'Bob' });
    await expect(provider.revoke(issued.serialNumber, 'keyCompromise')).resolves.toBeUndefined();

    const stateFile = path.join(stateDir, 'smime-dev-ca.json');
    const stored = JSON.parse(await (await import('node:fs/promises')).readFile(stateFile, 'utf-8'));
    expect(stored.revokedSerials).toContain(issued.serialNumber);
  });
});