Contents

Getting started

• Install — installation via pnpm, npm, or yarn
• Requirements — runtime floor and environment prerequisites
• Quick Start — minimal working usage sample

The Crypto Service ecosystem

• The Crypto Service ecosystem — full 18-package suite overview

Package reference

• Reference & Usage — features, configuration, and capabilities
• Examples — runnable sample code

Operational

• Development — build, lint, format, and test targets
• Security — vulnerability disclosure and cryptographic invariants
• Documentation — TypeDoc API docs and ecosystem guides
• Stability guarantees — SemVer axis and release policy
• License

Install

pnpm add @sebastienrousseau/crypto-middleware
# or
npm install @sebastienrousseau/crypto-middleware
# or
yarn add @sebastienrousseau/crypto-middleware

Requirements

• Node.js: ^22.0.0 or >=24.0.0 (active and maintenance LTS releases)
• Package Manager: pnpm >=9 (recommended) or npm >=10
• TypeScript: >=5.0 (when compiling with TypeScript)

Quick Start

import express from "express";
import { createCryptoMiddleware } from "@sebastienrousseau/crypto-middleware";

const app = express();
app.use(express.json());

app.use(
  createCryptoMiddleware({
    key: process.env.CRYPTO_KEY, // 256-bit hex key
    operations: ["decrypt-request", "encrypt-response"],
  }),
);

app.post("/api/data", (req, res) => {
  // req.body is already decrypted
  res.json({ received: req.body });
  // response is automatically encrypted
});

app.listen(3000);

The Crypto Service ecosystem

Crypto Service provides a complete cryptography stack across 14 specialized packages:

| Package | Role | Description | | :------------------------------------------------------------------------------------------------------------------------------------------------------ | :-------------- | :----------------------------------------------------------------------------------------------------------------------------- | | @sebastienrousseau/crypto-api | API Schemas | Shared TypeScript types and utilities for the Crypto Service Suite, defining the canonical API surface. | | @sebastienrousseau/crypto-benchmarks | Benchmarks | Benchmarks comparing classical and post-quantum cryptography: ops/sec, latency and throughput. | | @sebastienrousseau/crypto-cbom | CBOM | Cryptographic Bill of Materials generator and auditor (CycloneDX 1.6, SPDX 3.0). | | @sebastienrousseau/crypto-cli | Terminal CLI | Command-line interface: hashing, key generation, encryption, signing, HPKE, Argon2id and CBOM scans, with an interactive menu. | | @sebastienrousseau/crypto-edge | Edge Runtime | Edge-runtime cryptographic operations using the Web Crypto API, optimized for Cloudflare Workers, Vercel Edge, and Deno. | | @sebastienrousseau/crypto-kms | Cloud KMS | Unified KMS interface: AWS KMS and local providers implemented; GCP, Azure and Vault are stubs. | | @sebastienrousseau/crypto-lib | Core Library | Core library: post-quantum ML-KEM, ML-DSA and SLH-DSA, plus classical, modern and OpenPGP cryptography for TypeScript. | | @sebastienrousseau/crypto-lsp | IDE Analysis | Language server that flags weak and quantum-vulnerable cryptography in the editor, with quick fixes. | | @sebastienrousseau/crypto-mcp | AI Agents | Model Context Protocol server exposing cryptography tools to AI assistants and agents. | | @sebastienrousseau/crypto-middleware (this package) | Middleware | Cryptographic middleware for Express and Fastify: decrypt requests, encrypt responses, verify HMAC signatures and JWTs. | | @sebastienrousseau/crypto-prisma | ORM Adapter | Transparent field-level encryption extension for Prisma Client, using XChaCha20-Poly1305. | | @sebastienrousseau/crypto-react | React Hooks | React hooks and context provider for client-side cryptographic operations with zero boilerplate. | | @sebastienrousseau/crypto-sdk | Client SDK | A zero-dependency, typed HTTP client for the Crypto Service REST API, with full post-quantum support. | | @sebastienrousseau/crypto-server | HTTP API | A hardened Fastify REST API for cryptographic operations, with rate limiting, OpenAPI schemas, and post-quantum endpoints. | | @sebastienrousseau/crypto-testing | Test Support | Deterministic keys, fast mocks, and test fixtures for crypto-lib | | @sebastienrousseau/crypto-typeorm | ORM Adapter | TypeORM column-level encryption with a single decorator, powered by crypto-lib. | | @sebastienrousseau/crypto-vue | Vue Composables | Vue 3 composables for client-side cryptography | | @sebastienrousseau/crypto-wasm | Acceleration | Placeholder for a WebAssembly accelerator; no WebAssembly module ships yet. |

Overview

crypto-middleware provides transparent cryptographic operations for Express and Fastify applications. It can auto-decrypt incoming request bodies, encrypt outgoing responses, verify HMAC signatures on webhooks, and validate HS256 JWT bearer tokens -- all via a single middleware registration. Route matching via glob patterns lets you scope protection to specific endpoints.

Express

Configuration

| Option | Type | Required | Description | | :------------ | :--------- | :------- | :------------------------------------------------ | | key | string | * | Hex-encoded 256-bit key for encryption/decryption | | routes | string[] | No | Glob patterns for routes to apply middleware to | | operations | string[] | No | Operations to perform (see below) | | hmacKey | string | * | Hex-encoded HMAC key for signature verification | | jwtSecret | string | * | Secret for HS256 JWT verification | | jwtIssuer | string | No | Required iss claim for verify-jwt | | jwtAudience | string | No | Required aud value for verify-jwt |

* Required when the corresponding operation is enabled.

verify-jwt accepts only HS256 (any other alg, including none, is rejected), requires a numeric exp claim, checks nbf when present, and checks iss and aud when jwtIssuer / jwtAudience are set. Set both when the secret is shared with any other service.

Operations

| Operation | Description | | :----------------- | :----------------------------------------------------- | | decrypt-request | Decrypts incoming JSON bodies | | encrypt-response | Encrypts outgoing JSON responses | | verify-signature | Verifies HMAC-SHA256 from x-signature header | | verify-jwt | Verifies HS256 JWT from Authorization: Bearer header |

Route Matching

| Pattern | Matches | | :---------- | :--------------------------------------- | | /api/data | Exact match only | | /api/* | One path segment: /api/users, /api/1 | | /api/** | Any depth: /api/users/1/profile |

When routes is omitted or empty, middleware applies to all routes.

Fastify

import Fastify from "fastify";
import { cryptoPlugin } from "@sebastienrousseau/crypto-middleware";

const app = Fastify();

app.register(cryptoPlugin, {
  key: process.env.CRYPTO_KEY,
  operations: ["decrypt-request", "encrypt-response"],
});

app.post("/api/data", async (request) => {
  return { received: request.body };
});

app.listen({ port: 3000 });

The cryptoPlugin accepts the same configuration options as createCryptoMiddleware.

Examples

All examples are self-contained TypeScript files in the examples/ directory. Run any example with:

npx ts-node examples/<name>.ts

| Category | Example | Purpose | | :-------- | :------------------------------------ | :--------------------------------------- | | Express | express.ts | Full Express setup with encrypt/decrypt | | Fastify | fastify.ts | Fastify plugin registration | | Webhook | webhook.ts | HMAC signature verification for webhooks | | JWT | jwt.ts | JWT Bearer token verification | | Encrypted | encrypted.ts | Full encrypted request/response pipeline |

Development

pnpm --filter @sebastienrousseau/crypto-middleware run build
pnpm --filter @sebastienrousseau/crypto-middleware run test
pnpm --filter @sebastienrousseau/crypto-middleware run lint
pnpm --filter @sebastienrousseau/crypto-middleware run format

All 18 packages in the Crypto Service workspace maintain a 100% coverage floor across statements, branches, functions, and lines.

Security

Report vulnerabilities privately via GitHub Security Advisories or according to SECURITY.md. Never report security issues publicly.

The middleware verifies JWTs and HMAC signatures but does not rate-limit them. Register a rate limiter in the host application (for example @fastify/rate-limit or express-rate-limit) in front of the routes it protects, as crypto-server does.

Cryptographic operations use the @noble/* libraries, Node.js crypto and OpenPGP.js. @noble/post-quantum has not been independently audited and does not guarantee constant-time execution, and no module in this suite is FIPS 140-3 validated. Key zeroization is limited: JavaScript strings and garbage-collected buffers cannot be reliably wiped. See SECURITY.md.

Documentation

• Full Suite Documentation
• API Reference (TypeDoc)
• Developer Guide
• Security Policy
• Architecture & Design

Stability guarantees

Versions advance strictly one step at a time on the 0.0.x line (v0.0.1 → v0.0.2 → v0.0.3 ... → v0.0.999 → v0.1.0). Work for every release iteration begins on a dedicated feat/v<version> branch.

All 18 packages in the workspace move in lockstep. Public API signatures, cipher output formats, and serialization schemas are strictly versioned. Breaking changes to serialized formats or algorithm defaults are considered major breaking changes. Minimum toolchain upgrades (e.g. Node.js LTS floor) are governed by POLICIES.md.

License

Dual-licensed under Apache 2.0 or MIT, at your option.

Copyright (c) 2022-2026 Sebastien Rousseau and The Crypto Service Suite contributors.