hpke-http

hpke-http protects HTTP requests and replies. Send them with Python HTTPX, aiohttp, or TypeScript Fetch. Serve them with a Python ASGI app. The shared Rust engine checks each payload.

The published v4 packages include the shared key source and HHKD v2 discovery used below. The protocol specification gives the exact bytes, checks, and client and server steps. The Python and TypeScript v4 clients do not read HHKD v1 key records. Change clients and hosts together, or use separate endpoints.

Use the library

Send a request with Python

Set endpoint, psk, and psk_id from your app config. Keep one key source open for each full protected endpoint path while your app sends calls. Use separate sources for Bridge and Library. Short-lived clients can share a source.

from hpke_http.middleware.httpx import DiscoveredEndpoint, HPKEAsyncClient

async with DiscoveredEndpoint(endpoint) as key_source:
    async with HPKEAsyncClient(key_source, psk, psk_id) as client:
        response = await client.post("https://api.example.test/items", json={"name": "Ada"})
        print(response.status_code, response.json())
    async with HPKEAsyncClient(key_source, psk, psk_id) as client:
        response = await client.post("https://api.example.test/items", json={"name": "Grace"})
        print(response.status_code, response.json())

The first call sends GET then POST. The second sends POST alone while the key lease is valid. The client also accepts normal HTTPX file input; see the Python file example.

Serve protected requests with Python

Wrap a FastAPI or Starlette app. Supply the app, recipient private key, public key ID, and key lease. The app also supplies PSK lookup and an atomic replay check shared by all server workers.

from hpke_http.middleware.fastapi import HPKEMiddleware

protected_app = HPKEMiddleware(
    app, private_key, key_id, resolve_psk, admit_replay,
    key_use_for_s=lease_seconds,
    transport_path="/protected",
)

The host checks the full request before it calls the app. The app reads files and other bodies through its normal request API. See the Python guide for aiohttp, forms, SSE, and cross-origin browser setup.

Use Fetch in TypeScript

Set psk and pskId as Uint8Array values from your app config. The PSK needs at least 32 bytes of entropy. Its public ID must differ from the PSK.

import { DiscoveredEndpoint, createHpkeFetch, initialize } from "@dualeai/hpke-http/browser";

await initialize();
const keySource = new DiscoveredEndpoint("https://api.example.test/protected");
const hpkeFetch = createHpkeFetch({
  key: keySource,
  psk,
  pskId,
});

try {
  const response = await hpkeFetch("https://api.example.test/items", {
    method: "POST",
    body: "payload",
  });
  console.log(response.status);
  const next = await hpkeFetch("https://api.example.test/items", {
    method: "POST",
    body: "another payload",
  });
  console.log(next.status);
} finally {
  hpkeFetch.close();
  keySource.close();
}

The first call sends GET then POST. The second sends POST alone while the key lease is valid. Other clients can use keySource while it stays open. Use a different source for Library's endpoint path.

Fetch keeps its normal body types. Large uploads need a runtime that can send a request stream; browser support and HTTP/1.x routes can limit that path. A small buffered outer POST uses the same protected wire. See the TypeScript guide for Node, browser, and SSE calls.

Use the Rust crate

Add the published crate:

cargo add hpke-http@4.0.0

Use Client and Server with your HTTP stack. The crate does no network I/O. The crate docs show complete and streamed transactions.

Build and runtime support

Use published releases for package builds, or use Development to build this checkout.

The Rust crate requires Rust 1.87 or newer. Python supports CPython 3.10 through 3.14; release wheels target Linux x86-64 and AArch64 and macOS universal2. Windows Python builds are not supported. The npm package supports Node.js 24 and browsers with WebAssembly, Fetch, Web Crypto, and Web Streams. It has explicit ./node and ./browser exports and no root export.

Technical details

Protocol specification

The central specification defines the hpke-http/3 request and response bytes, the HHKD v2 key record, the HTTPS exchange, checks, limits, and pseudocode. It links the frozen test vectors. Use it when you make another implementation or inspect the wire format. The Rust crate docs show executable API transactions.

A client gets one key by HTTPS GET or uses a pinned key, then sends one protected HTTPS POST to the same endpoint. The inner method, target, fields, body, and response status are checked protected data. The endpoint, public IDs, size, record count, and timing remain visible; the format adds no padding.

Host duties

A server resolves a public PSK ID and makes one atomic replay decision shared by all workers that accept the same credentials. It keeps clear request data from the app until the full request, END, and outer body EOF pass. It also checks its logical target policy before app dispatch. Each request gives one response right. The client checks each SSE block before it gives that block to the caller; it gives a finite reply only after END and outer EOF. Use HTTPS and give each PSK at least 32 bytes of entropy.

The Python ASGI host keeps up to 256 KiB of checked request data in memory, then uses a temporary file. An incoming ASGI event can use more memory. Set service limits for concurrent uploads, temporary disk, and time, as well as the protocol byte limit. For a planned recipient key change, follow the worker and lease steps in the specification.

Native engine

The protocol identifier is hpke-http/3. The Rust crate owns the wire format, HPKE state, replay identity, limits, and response record checks. It does no network I/O. Python calls it through PyO3; TypeScript calls it through WebAssembly. There is no pure-Python or pure-TypeScript cryptographic fallback.

Repository layout

rust/hpke-http/       safe protocol engine and executable API examples
python/               Python API, PyO3 boundary, and HTTP framework adapters
typescript/           TypeScript API, WASM boundary, and native Fetch adapter
cicd/                 tag-derived coordinated release tooling

The language projects own key GET and record handling, runtime lifecycle, and HTTP integrations. Generated binding APIs are private.

Development

Install Rust with rustup, then use its cargo and rustc for the WASM target. Put the Rust toolchain ahead of any Rust tools from another package manager. Install uv and Node.js 24 before you run these commands:

rustup update stable
export PATH="$(dirname "$(rustup which cargo --toolchain stable)"):$PATH"
rustup target add --toolchain stable wasm32-unknown-unknown
make install
make install-wasm-bindgen
make build
make test

Use make build-rust, make build-python, or make build-typescript to build one language. Use make test-rust, make test-python, or make test-typescript to check one language. make package writes Rust, Python, and npm packages to artifacts/. Use the matching smoke-python-wheel, smoke-python-sdist, or smoke-typescript target to check a package. Local Python targets can update uv.lock when dependencies change; CI uses the locked versions.

wasm-bindgen-cli 0.2.128 and the Rust wasm32-unknown-unknown target are required for the TypeScript build. Installing the pinned CLI from source needs Rust 1.88 or newer. Use the current stable Rust release to build all bindings. The TypeScript runtime test needs Chrome or Chromium. Set CHROME_BIN if the browser is not in a standard path.

Security

See the security policy for supported releases and private reporting. Give each PSK at least 32 bytes of entropy. Do not use it as its public PSK ID. Use an atomic replay store shared by all server workers that can process the same credentials.

hpke-http 4.0.1