@uuaid/plinth

Plinth is the stone base a pillar stands on. Authenticated mail still stands on Pillar. When you do not want the column (UUAID) visible between hops, you stand on Plinth.

Pseudonymous Link-invariant Network Transit Hops

This is a sibling of @uuaid/pillar, not a fork. Pillar envelopes keep sender and recipient in the clear on purpose (inbox auth, F1 sender binding). Plinth is a new packet that strips those identifiers hop by hop.

What it is

1. Mix hops — each hop unwraps one layer, sees only the previous connection and the next hop, forwards a 16 KiB packet. No hop log can contain both endpoints.
2. OpenRouter-shaped gateway — POST /v1/chat/completions and GET /v1/models. The bearer is an unlinkable mix ticket, not a UUAID. model is agent/<role> in v0. openai/... goes through the same mix hops when OPENAI_API_KEY or OPENROUTER_API_KEY is set; the key stays at the exit and never rides the mix wire. OpenRouter :free slugs and openrouter/free take the same path. Without a key, those still return 501 model-not-routed.

Conversation continuity is the mixer trick: deposit a request, withdraw a reply to a fresh address. SURBs carry the return path. Session tickets derive the next note so turn N+1 does not reprint turn N’s ticket on the wire.

Honest limit

One operator is not an untraceable mixnet. Three processes on one Mac prove log unlinkability (hop 1 never writes Bob; hop 3 never writes Alice; hop 2 writes neither). A global passive adversary who sees every NIC, or a single operator who runs every hop, can still correlate. Production needs independent operators. Cover traffic is designed, not shipped. Do not claim “untraceable.”

See THREAT-MODEL.md and LAYER.md.

Install

# from the sibling checkout
cd /Users/z/zz-station/pillar/uuaid-plinth
npm install

Node.js >= 20. Depends on @uuaid/pillar (file: link to ../uuaid-pillar-node) for sealPayload / openPayload, jcs, and Keychain. Hop AAD is uuaid-plinth-hop/1:<packetId>.

Quick start (local demo — one operator)

node bin/plinth.mjs demo --port 8788
# prints gateway URL + a ticket

curl -s http://127.0.0.1:8788/v1/models
curl -s http://127.0.0.1:8788/v1/chat/completions \
  -H "Authorization: Bearer <ticket>" \
  -H "Content-Type: application/json" \
  -d '{"model":"agent/echo","messages":[{"role":"user","content":"hi"}],"stream":false}'

stream: true is rejected (400). SSE timing would undo the mix.

Open the same origin in a browser: http://127.0.0.1:8788/ — issue a ticket, send a message. The tab is a client (fetch + /src/client.mjs). Mix hops and the gateway stay on Node.

Browser

Yes, as a client. No, as a public mix hop.

A page can wrap the OpenRouter-shaped API with ordinary fetch. That is how agents will run in a tab, a WebView, or an extension. @uuaid/plinth/client and @uuaid/plinth/ticket-format have no node: imports.

A browser tab cannot be a mix node: it has no stable inbound address, cannot listen on /v1/packet, and would leak the hop through the user’s residential IP. Gateway and hops stay on Node (or another always-on host). Last-mile Pillar crypto still uses Node’s node:crypto via @uuaid/pillar.

import { complete, issueTicket, listModels } from "https://your-gateway/src/client.mjs";

CORS is open on the gateway (Access-Control-Allow-Origin: *) so a page on another origin can call it. The gateway still sees the caller’s IP. It does not store Referer or a user field.

Bins

| Bin | Role | |---|---| | plinth | init, send, recv, ticket, demo | | plinth-mix | one mix hop (--port, --delay, --name) | | plinth-gateway | OpenRouter-shaped HTTP (--directory, --allow-issue, --last-mile) |

Last mile

The mix wire is never a Pillar envelope. An optional exit identity (fresh key, not Alice) may seal() a Pillar v2 envelope and POST it to the existing carrier so a pillar-responder can answer. The fleet agent sees the exit UUAID, not Alice.

Tests

npm test          # unit
npm run test:int  # three-hop blender proof + gateway
npm run test:all

The integration test is the product: hop logs, SURB reply, ticket unlink, constant size, replay reject, gateway schema.

License

Apache-2.0.