# hpke-http
`hpke-http` protects bounded HTTP requests and checked response records with one
shared Rust protocol engine. Python calls that engine through PyO3. TypeScript
calls the same engine through WebAssembly and includes an adapter for the
runtime's native Fetch API.
The protocol identifier is `hpke-http/2`. It is the only protocol implemented
in this repository. There is no pure-Python or pure-TypeScript cryptographic
fallback.
## Repository layout
```text
rust/hpke-http/ safe protocol engine and executable protocol contract
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 Rust crate owns protected message encoding, HPKE operations, limits,
validation, replay identity, and response record state. The language projects
own key GET and record handling, runtime lifecycle, and HTTP integrations.
Generated binding APIs are private.
## Install and runtime support
Build this checkout with the commands in [Development](#development) to use
`hpke-http/2`. Package registry installs select a published release, not 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.
## Protocol properties
Protocol version 2 uses:
- RFC 9180 HPKE PSK mode with X25519, HKDF-SHA256, and ChaCha20-Poly1305;
- a canonical known-length Binary HTTP request from RFC 9292, with RFC 9292
field-line encoding in response START;
- a project-specific request envelope and request-bound response keys; and
- one checked response START, a checked DATA record per SSE block, and a checked END.
The protocol is not wire-compatible with RFC 9458 Oblivious HTTP. HTTPS is
still required because endpoints, public key and PSK identifiers, message
sizes, and timing remain visible.
Servers resolve a public PSK ID and then make one atomic replay-admission
decision. The authenticated plaintext remains inside the engine until that
decision succeeds. Each request can create and open only one protected
response. A client uses the START fields only after its tag passes. It gets each
SSE block after that block's tag passes, before the server sends END. A finite
response becomes complete only after END and the real outer body EOF.
The engine accepts whole requests, finite replies, and live SSE blocks. The
default body limit is 8 MiB per request, finite response, or SSE block; a live
SSE stream has no total body cap. It supports opt-in gzip or zstd body compression in the Rust
protocol layer, with bounded decompression in every binding. This is separate
from HTTP `Content-Encoding`: high-level adapters still require identity
logical content coding. SSE records use no private body coding. The engine does
no network I/O; the Python and Fetch adapters can discover one key. There is
no suite negotiation. Compression can leak body information through
ciphertext length; enable it only when attacker-controlled data cannot be
combined with secrets in the same body.
Recipient keys use X25519. Public recipient-key and PSK identifiers are
non-empty and at most 255 bytes; PSKs must be at least 32 bytes long, contain
at least 32 bytes of entropy, and differ from their public IDs. Native objects
copy credentials. Closing them releases native copies, but it cannot erase
caller-owned Python `bytes` or JavaScript `Uint8Array` values.
## Key discovery
One configured HTTPS endpoint serves the public key through GET and receives
protected requests through POST. A client gets the key before each discovered
call. The GET sends no logical authorization, cookies, or PSK ID. The client
accepts no redirect and stores no app key cache. A pinned key uses the same
POST endpoint and sends no GET. The client accepts logical requests at one
fixed HTTPS origin; a gateway can set a different `target_origin` or
`targetOrigin` and the ASGI server's `expected_authority`.
Origin checks fold DNS case and IDNA names, normalize IPv6 and the default
port 443, and keep other ports distinct. A wrong logical origin fails before
the client reads its body or sends GET.
The GET body is exactly `"HHKD" || 0x01 || id_len:u8 || id || x25519_public_key[32]`.
The ID length is 1 through 255, so the full record is 39 through 293 bytes.
The server sends `application/octet-stream` and `Cache-Control: no-store`.
Clients reject any other record form or extra bytes. Version `0x01` describes
this key record; request and response bytes still use `hpke-http/2`. There is
no earlier discovery JSON, old route, or old client API path.
The server holds one recipient key. All workers for an endpoint must use that
key; a key change across mixed workers can make a request fail. The adapters
do not retry a protected POST. If its reply is lost, the caller does not know
whether the app ran. The added GET is one more network round trip on each
discovered call. For browser calls, outer CORS must cover GET, POST preflight,
POST, and fault replies.
## Rust
The `hpke-http` crate exposes the network-independent client/server state
machine. Its crate-level rustdoc contains an executable complete transaction,
the exact protocol bytes, replay contract, limits, and stable error categories.
## Python
The Python package provides the low-level state machine, buffered finite replies,
and live SSE adapters
for `httpx`, `aiohttp`, and FastAPI/Starlette. See the
[Python package README](python/README.md).
The key values and `send_envelope` below come from the application.
```python
from hpke_http import Client, Method, Request
with Client(server_public_key, key_id, psk, psk_id) as client:
transaction = client.protect(
Request(Method.POST, "api.example.test", "/items", body=b"payload")
)
try:
protected_response = send_envelope(transaction.envelope)
response = transaction.open_response(protected_response)
finally:
transaction.close()
```
## TypeScript
The TypeScript package provides explicit browser and Node entry points and a
`createHpkeFetch` adapter over native Fetch with live SSE bodies. See the
[TypeScript package README](typescript/README.md).
```ts
import { createHpkeFetch, initialize } from "@dualeai/hpke-http/browser";
await initialize();
const hpkeFetch = createHpkeFetch({
endpoint: "https://api.example.test/protected",
key: { kind: "discover" },
psk,
pskId,
});
try {
const response = await hpkeFetch("https://api.example.test/items", {
method: "POST",
body: "payload",
});
console.log(response.status);
} finally {
hpkeFetch.close();
}
```
Axios and TanStack Query adapters are medium-term work. Java, Kotlin, and Swift
bindings are dormant options. Any activated binding uses this Rust engine and
joins the same coordinated release pipeline.
## 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:
```sh
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 test-python` runs `make test-static` and
`make test-func`. `make package` packs all three languages from a clean checkout;
`package-rust`, `package-python-wheel`, `package-python-sdist`, and
`package-typescript` select one package type. CI and release jobs use Makefile
targets for source builds, tests, package checks, and smoke tests. The release
wheel job reads its build options from the Makefile and uses `maturin-action` for
each platform.
Local Python targets update `uv.lock` when dependencies change. CI uses the
locked versions. Package targets write to `artifacts/`. Run
`make smoke-python-wheel`, `make smoke-python-sdist`, or `make smoke-typescript`
after you build the matching package. Set `EXPECTED_VERSION` to the release
tag's numeric version, without its `v` prefix, when you check a release package.
The separate CodSpeed workflow measures complete public-API transactions in
Rust, Python, and Node/WASM at empty, 1 KiB, 1 MiB, and 8 MiB body sizes. It
also measures pinned and discovered HTTPX and Fetch calls with in-memory
transports; those runs include no network wait. The body-size runs prepare keys
and message bodies outside the measured step. Only the native Rust suite enables
CodSpeed's allocation-memory mode. There are no local stopwatch scripts or
hardware-dependent timing thresholds.
`wasm-bindgen-cli` 0.2.128 and the Rust `wasm32-unknown-unknown` target are
required for the TypeScript build. CI uses Rust 1.98.1 and a shared Rust build
cache. The crate supports Rust 1.87 and newer, but installing the pinned
`wasm-bindgen-cli` from source needs Rust 1.88 or newer. Use the current stable
Rust release to build all bindings. The TypeScript runtime test also requires
Chrome or Chromium; set `CHROME_BIN` for a nonstandard path.
## Versions and releases
Package versions, the protocol ID, and the binding ABI are separate values.
Python and TypeScript reject a native engine whose three-part identity does not
match their package.
Release versions come from an exact `vMAJOR.MINOR.PATCH` Git tag through
`cicd/version.sh`. The release workflow injects that one version into Cargo,
Python, and npm package metadata before it builds or tests any artifact. The
crate, Python distributions, npm package, and GitHub release then use the same
tag and workflow.
This source tree targets the next major release with protocol `hpke-http/2`.
Its parser and bindings have no earlier wire mode or API fallback. The exact
release tag sets the package versions after this code is ready.
The protocol details live in Rust module documentation, public API docs, and
frozen known-answer tests owned by the Rust core. This repository does not
maintain a separate specification or architecture-decision document tree.
## Security
See the [security policy](SECURITY.md)
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.
The core standards are [RFC 9180](https://www.rfc-editor.org/rfc/rfc9180.html)
and [RFC 9292](https://www.rfc-editor.org/rfc/rfc9292.html). Response-key
derivation follows the pattern in
[RFC 9458 section 4.4](https://www.rfc-editor.org/rfc/rfc9458.html#section-4.4),
but `hpke-http/2` is not an Oblivious HTTP profile.