Qastle Wallet API integration & Krown Blockchain OpenData

Account binding & session APIs

Token-based linking of a user's Qastle wallet address to your platform. Supports the wallet's import/recovery flow so a customer can re-encrypt an existing seed with quantum-secure keys, then expose a stable internal `account_id`.

Multi-chain transaction export

Single endpoint for Krown, BTC, ETH (mainnet + Base), BNB, USDT. Returns block height, hash, counterparty, asset, value, fee, and signature scheme (ECDSA vs Dilithium). Designed for ledger reconciliation.

Token swap event capture

Hooks for the in-app swap flow (WETH, DAI, WBTC, USDT on Ethereum mainnet) so a finance team gets a real-time record of every swap, with execution price and gas cost annotated.

WalletConnect orchestration

Server-side bridge to WalletConnect v2 sessions: approve dApp connections, route `eth_signTypedData` and `personal_sign` requests through a policy layer, and log every approval for audit.

Quantum entropy attestation

Capture the QRNG2 entropy attestation produced at key generation, store it alongside the public key, and expose a `/attestation/{address}` endpoint so counterparties can verify the wallet's entropy provenance.

Webhook & streaming layer

Push notifications for confirmed transfers, failed signing requests, low-balance thresholds, and PQC key rotation events. Delivered via signed HTTPS webhooks or Kafka topics.

1. Crypto-treasury reconciliation for a Krown-native business

A merchant accepting KRN, BTC, and USDT through Qastle wants daily balance snapshots and per-transaction CSVs to import into Xero or NetSuite. Our pipeline calls the wallet's transaction endpoint per address, normalizes outputs into a common schema (`tx_hash`, `chain`, `asset`, `amount`, `fee`, `counterparty`), and posts ledger entries via the accounting platform's API.

2. PQC-aware audit trail for regulated custodians

Custodians must demonstrate that signing keys were generated with audited entropy. We extract Qastle's QRNG2 attestation and Dilithium signature metadata for every outbound transaction, store both in WORM storage, and expose a `/audit/proof/{tx_hash}` endpoint for examiners.

3. Real-time dApp policy enforcement

An enterprise allows staff wallets to interact only with approved dApps. Our middleware intercepts WalletConnect requests, checks the peer dApp against an allow-list, applies spend-limit rules, and either auto-approves or pushes a Slack approval to a compliance officer.

4. Tax export across multiple chains

End users need a single year-end report covering Krown, Bitcoin, Ethereum (incl. Base), and BNB. We aggregate Qastle's per-chain history, attach FX rates from CoinGecko at transaction time, and emit IRS Form 8949 and HMRC self-assessment formats.

5. Counterparty KYT and sanctions screening

Before a high-value transfer, the back office screens the destination address against Chainalysis or TRM Labs. Our integration relays the prepared transaction from Qastle, fetches a risk score, and only releases the signing request if the score falls below the configured threshold.

Deliverables checklist

• OpenAPI 3.1 specification with examples for every endpoint
• Protocol analysis report: WalletConnect v2 handshake, RPC calls, entropy attestation format
• Runnable source for Python (FastAPI) or Node.js (NestJS) reference servers
• Postman collection plus pytest / vitest integration suites
• Compliance brief: data minimization, retention, and consent-record templates
• Optional Docker compose for local sandbox with mocked Krown RPC

API example: pull multi-chain transactions

POST /api/v1/qastle/transactions
Content-Type: application/json
Authorization: Bearer <ACCESS_TOKEN>

{
  "account_id": "acc_8f1c...",
  "chains": ["KRN", "BTC", "ETH", "BNB"],
  "from_date": "2026-03-01",
  "to_date":   "2026-03-31",
  "include_signature_meta": true,
  "page": 1,
  "page_size": 100
}

200 OK
{
  "items": [
    {
      "tx_hash": "0xa3...",
      "chain": "ETH",
      "asset": "USDT",
      "amount": "250.00",
      "fee": "0.0011",
      "counterparty": "0xbe...",
      "block": 21504123,
      "signature": { "scheme": "ECDSA-secp256k1" },
      "ts": "2026-03-14T09:21:12Z"
    }
  ],
  "next_cursor": "eyJwYWdlIjoyfQ=="
}

API example: verify a Dilithium signature

POST /api/v1/qastle/pqc/verify
Authorization: Bearer <ACCESS_TOKEN>

{
  "address":   "krn1qastle...",
  "payload":   "0xdeadbeef...",
  "signature": "0x9f12...",
  "scheme":    "DILITHIUM3"
}

200 OK
{ "valid": true, "verified_at": "2026-04-28T11:02:44Z",
  "attestation_id": "qrng2_2026Q1_8821" }

API example: WalletConnect approval webhook

POST {your-callback}
X-Qastle-Signature: t=1714...,v1=...

{
  "event": "wc.session.proposed",
  "session_id": "wc:8f5d...",
  "peer": { "name": "Uniswap", "url": "https://app.uniswap.org" },
  "chains": ["eip155:1", "eip155:8453"],
  "methods": ["personal_sign", "eth_signTypedData_v4"],
  "expiry_ts": 1714010099
}

About our studio

We are an independent technical studio focused on App interface integration and authorized API integration. Our team brings hands-on experience from fintech, payments, blockchain analytics, and protocol engineering. We have shipped integrations for banking apps, payment wallets, brokerages, and Web3 wallets across Asia, Europe, and the Americas.

• Protocol analysis, WalletConnect / RPC reverse engineering, and post-quantum primitives
• Production API gateways with rate limits, audit logs, and signed webhooks
• Custom Python / Node.js / Go SDKs and end-to-end test harnesses
• Source code delivery from $300 — runnable code plus documentation; pay after delivery upon satisfaction
• Pay-per-call hosted API — no upfront fee, billed per request, ideal for variable workloads

Contact

To request a quote, share your target app and requirements, or discuss a proof-of-concept around Qastle Wallet and the Krown Blockchain, please use our contact page.

Open contact page

Engagement workflow

1. Scope confirmation: which Qastle data (transactions, balances, signatures, dApp events) and which downstream system.
2. Protocol analysis & API design (2–5 business days).
3. Build and internal validation against a Krown RPC sandbox (3–8 business days).
4. Documentation, sample requests, and test cases (1–2 business days).
5. First delivery typically lands in 5–15 business days; PQC verification add-ons may add 2–3 days.

FAQ

What do you need from us to start?

Can you handle the post-quantum signature verification?

How do you handle compliance for crypto data?

What if Qastle releases a breaking update?