openkitx403 — Python Server SDK

FastAPI middleware for OpenKitx403 wallet-based authentication. Add Solana wallet verification to any API endpoint with one line.

🚀 Installation

pip install openkitx403
# or
poetry add openkitx403

⚡ Quick Start

from fastapi import FastAPI, Depends
from openkitx403 import OpenKit403Middleware, require_openkitx403_user

app = FastAPI(title="My Wallet-Protected API")

# Attach OpenKitx403 middleware
app.add_middleware(
    OpenKit403Middleware,
    audience="https://api.example.com",
    issuer="my-api-v1",
    ttl_seconds=60,
    bind_method_path=False, # Set True to bind challenges to specific paths
    origin_binding=False,
    replay_backend="memory"
)

@app.get("/protected")
async def protected(user = Depends(require_openkitx403_user)):
    """Example protected endpoint"""
    return {
        "message": f"Authenticated as {user.address}",
        "wallet": user.address
    }

@app.get("/public")
async def public():
    """Public endpoint - no authentication required"""
    return {"message": "Hello World"}

🔒 Optional Token Gating

from openkitx403 import OpenKit403Middleware
from solana.rpc.api import Client
from solders.pubkey import Pubkey

solana_client = Client("https://api.mainnet-beta.solana.com")

async def check_token_holder(address: str) -> bool:
    """Example: verify wallet holds specific token"""
    try:
        pubkey = Pubkey.from_string(address)
        resp = solana_client.get_token_accounts_by_owner(
            pubkey,
            opts={"mint": str(Pubkey.from_string("YOUR_TOKEN_MINT"))}
        )
        return len(resp.value) > 0
    except Exception as e:
        print("Token check failed:", e)
        return False

app.add_middleware(
    OpenKit403Middleware,
    audience="https://api.example.com",
    issuer="my-api-v1",
    token_gate=check_token_holder,
)

🛤️ Exclude Paths from Authentication

app.add_middleware(
    OpenKit403Middleware,
    audience="https://api.example.com",
    issuer="my-api-v1",
    excluded_paths=["/health", "/docs", "/openapi.json"]
)

🧩 API Reference

OpenKit403Middleware

FastAPI middleware that adds OpenKitx403 authentication to your routes.

Configuration Parameters:

🔐 Token Gate Function Signature

Your token gate function must:

• Accept a single address: str parameter (base58-encoded public key)
• Return bool (True = allowed, False = denied)
• Can be async or sync

async def my_token_gate(address: str) -> bool:
    # Your validation logic
    return True # or False

🎯 Accessing User Information

Use the require_openkitx403_user dependency to access authenticated user:

from fastapi import Depends
from openkitx403 import require_openkitx403_user, OpenKit403User

@app.get("/profile")
async def profile(user: OpenKit403User = Depends(require_openkitx403_user)):
    return {
        "address": user.address,
        "challenge": user.challenge # Original challenge object
    }

🔧 Custom Replay Store

By default, middleware uses in-memory replay protection. For production with multiple servers:

from openkitx403 import ReplayStore

class RedisReplayStore:
"""Example Redis-based replay store"""
    def __init__(self, redis_client):
        self.redis = redis_client

    async def check(self, key: str, ttl_seconds: int) -> bool:
        return await self.redis.exists(key)

    async def store(self, key: str, ttl_seconds: int) -> None:
        await self.redis.setex(key, ttl_seconds, "1")

# Use custom store
app.add_middleware(
    OpenKit403Middleware,
    audience="https://api.example.com",
    issuer="my-api-v1",
    replay_store=RedisReplayStore(redis_client)
)

🔑 Dependencies

• fastapi - Web framework
• starlette - ASGI toolkit
• solders - Solana SDK (for types)
• base58 - Base58 encoding
• pynacl - Ed25519 signature verification

📚 Documentation

• OpenKitx403 Protocol Specification
• Client SDK Documentation
• Security Best Practices

🪪 License

MIT