typesecure

typesecure is a classification-first security core for TypeScript projects.

Instead of starting with crypto primitives, it starts with what actually causes most security incidents in web apps: data leaving the boundary it should never cross (logs, analytics, error trackers, headers, client bundles, etc).

You “type” your data as public | pii | secret | token | credential, and typesecure helps you enforce safe handling using TypeScript + runtime checks.

Features

• Classification types: PublicString, PIIString, SecretString, TokenString, CredentialString.
• Runtime validation: Zod-backed constructors (secretText(), piiText(), ...).
• Redaction: redact() and safeJsonStringify() prevent secret/PII leakage.
• Policy enforcement: defaultPolicy(), assertAllowed(), audit() help block unsafe crossings.

Good for / Use when

• You need to stop leaks early: preventing secrets/PII from ending up in logs, analytics, error trackers, or client bundles.
• You want safe defaults: making insecure behavior harder than secure behavior.
• You want guardrails at the boundary: before logging, emitting telemetry, making network calls, or writing to storage.

Not a fit / Don’t use when

• You need a full security platform (hosted policy registry, enterprise controls). typesecure is a library.
• You need production-grade crypto primitives. Use well-reviewed, purpose-built libraries and treat crypto carefully.
• You only want compile-time types with zero runtime behavior. typesecure deliberately includes runtime checks/redaction.

Installation

Requires Node.js >=18.18.0.

# Using npm
npm install typesecure

# Using yarn
yarn add typesecure

# Using pnpm
pnpm add typesecure

Usage

Classification-first data handling

import {
  piiText,
  secretText,
  token,
  publicText,
  redact,
  safeJsonStringify,
  defaultPolicy,
  assertAllowed,
  policyLog,
} from "typesecure";

const userEmail = piiText("[email protected]");
const sessionToken = token("abc.def.ghi");
const dbPassword = secretText(process.env.DB_PASSWORD ?? "");

// Redact before logging / serialization
console.log(redact({ userEmail, sessionToken, dbPassword }));
console.log(
  safeJsonStringify({ userEmail, sessionToken, dbPassword }, undefined, 2),
);

// Enforce policy before a boundary crossing
const policy = defaultPolicy();
assertAllowed(policy, "network", { sessionToken }); // allowed
// assertAllowed(policy, 'log', { dbPassword }); // throws

// Safe logging helper with enforcement
policyLog(policy, console, "info", publicText("login_ok"), { userEmail });

Express / Next.js examples

// Express middleware example
import {
  safeLoggerAdapter,
  defaultPolicy,
  assertAllowed,
  token,
} from "typesecure";

const log = safeLoggerAdapter(console);
const policy = defaultPolicy();

app.use((req, _res, next) => {
  const auth = req.headers.authorization?.replace(/^Bearer\s+/i, "");
  if (auth) {
    const t = token(auth);
    assertAllowed(policy, "network", { t });
    log.info({ route: req.path, auth: t }); // will be redacted
  }
  next();
});

API Reference

Classification

• publicText(value: string): PublicString
• piiText(value: string): PIIString
• secretText(value: string): SecretString
• token(value: string): TokenString
• credential(value: string): CredentialString
• reveal(value): string (intentionally explicit)

Redaction

• redact(value): value (deep traversal)
• redactText(value): string (mask sensitive fragments in plain text)
• detectText(value): StringDetection[] (return ranges/kinds for audit workflows)
• safeJsonStringify(value): string
• safeLoggerAdapter(consoleLike)
• Redaction options:
  • guessByKey (default true): redact suspicious keys like password, token, apiKey.
  • guessByValue (default true): auto-detect and redact sensitive-looking values.
  • useDefaultValueDetector (default true): keep built-in rule-based detectors on/off.
  • stringDetectors: add custom detectors (for NER/ML or domain-specific logic).
  • minDetectionConfidence (default 0): ignore low-confidence custom detections.
• Value detection masks only the sensitive fragments inside a larger string (instead of replacing the whole text), including:
  • PII: email, phone, SSN, date of birth (YYYY-MM-DD), IPv4 address, payment card numbers (Luhn-validated).
  • Secrets/tokens: JWTs, private key PEM blocks, GitHub tokens, AWS access keys, Stripe secret keys, OpenAI-style sk-... keys, credential pairs (user:pass), high-entropy token-like strings.

Example custom detector (NER/ML-style integration):

const out = redact(
  { text: "Customer Jane Doe uses [email protected]" },
  {
    stringDetectors: [
      (value) => {
        const name = "Jane Doe";
        const idx = value.indexOf(name);
        return idx >= 0
          ? [{ start: idx, end: idx + name.length, kind: "pii", confidence: 0.92, source: "ml.ner" }]
          : [];
      },
    ],
    minDetectionConfidence: 0.8,
  },
);

Policy

• defaultPolicy(): Policy
• assertAllowed(policy, action, data): void
• audit(policy, action, data): AuditEvent
• policyLog(policy, logger, level, ...args): void

Security Considerations

Security is as much about preventing leaks as it is about cryptographic correctness. typesecure focuses on preventing accidental secret/PII exposure across common boundaries.

If you need cryptography for production-grade requirements, prefer well-reviewed primitives and consult a security professional. For production applications with high security requirements, consider:

1. Consulting a security professional
2. Using specialized security libraries
3. Keeping dependencies updated
4. Implementing proper key management
5. Using hardware security modules (HSMs) for key storage when possible
6. Conducting regular security audits
7. Following the latest NIST recommendations

Development

To contribute to this project:

1. Clone the repository
2. Install dependencies with pnpm install
3. Run tests with pnpm test
4. Build the package with pnpm build
5. Run Enron dataset integration tests with pnpm test:data

Optional: external dataset setup

For larger redaction/policy experiments (Enron + Synthea FHIR), fetch datasets locally:

pnpm data:setup

This command downloads and extracts to:

• data/enron-maildir
• data/synthea_sample_data_fhir_latest

Notes:

• data/ is gitignored and not published to npm.
• pnpm test excludes dataset suites by default.
• pnpm test:data runs Enron dataset tests with verbose output.
• pnpm test:data:synthea runs Synthea-specific dataset tests.
• pnpm test:data:all runs all dataset suites.
• You can override source URLs with ENRON_URL=... and/or SYNTHEA_FHIR_URL=....
• You can change destination with DATA_DIR=/path/to/data.

Dataset sources:

• Enron: https://www.cs.cmu.edu/~enron/
• Synthea: https://github.com/synthetichealth/synthea-sample-data/

This project uses TypeScript for type safety, Jest for testing, and ESLint for code quality.

Dataset Acknowledgements

We use these public datasets for redaction and policy testing:

• CMU Enron Email Dataset
• Synthea Sample Data

Personal note: I am especially interested in the historical context around Enron, including how it was able to happen and the improvements in governance and controls that followed.

License

MIT © Arvid Berndtsson

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.