bpc-server

Python server-side middleware for the BPC (Bound Pair Credentials) protocol. Verifies BPC-signed requests in FastAPI and Flask applications using the full 12-step pipeline from the BPC spec v1.0.

Install

pip install bpc-server[fastapi]   # FastAPI + Starlette
pip install bpc-server[flask]     # Flask
pip install bpc-server[all]       # Both

FastAPI

from fastapi import FastAPI, Request
from bpc_server import BPCFastAPIMiddleware, InMemoryPairRegistry, PairRecord

app = FastAPI()
registry = InMemoryPairRegistry()

# Register a pair (in production, load from your database)
registry.register(PairRecord(
    pair_id="pair_abc123",
    name="my-agent",
    scope="read-write",
    mode="development",
    public_key_jwk={...},  # from bpc-client registration
    secret_hash="argon2id_hash_here",
))

app.add_middleware(BPCFastAPIMiddleware, registry=registry)

@app.get("/api/data")
async def get_data(request: Request):
    pair = request.state.bpc_pair  # BPCVerificationResult
    return {"pair_id": pair.pair_id, "scope": pair.pair.scope}

Flask

from flask import Flask, g
from bpc_server import BPCFlaskMiddleware, InMemoryPairRegistry

app = Flask(__name__)
registry = InMemoryPairRegistry()
BPCFlaskMiddleware(app, registry=registry)

@app.route("/api/data")
def get_data():
    return {"pair_id": g.bpc_pair_id}

Standalone Verifier

from bpc_server import BPCVerifier, InMemoryPairRegistry, InMemoryNonceStore

verifier = BPCVerifier(registry=registry, nonce_store=InMemoryNonceStore())
result = verifier.verify(headers=request.headers, method="GET", path="/api/data")
if not result.ok:
    return 401, result.error_code

12-Step Verification Pipeline

1. Headers present (X-BPC-Pair-ID, X-BPC-Signature, X-BPC-Signed-Data, X-BPC-Version)
2. Pair exists and is active (not revoked, not expired)
3. Pair not locked out
4. Decode and parse canonical payload
5. Protocol version check ("1.0")
6. Timestamp within ±60s window
7. Nonce not seen before (replay prevention)
8. Method and path match payload
9. Body hash match (SHA-256)
10. ECDSA-SHA-256 signature valid
11. Scope enforcement (read / read-write / admin)

See the full spec.