proxmox/rpc-translator-138/SMART_INTERCEPTION_IMPLEMENTED.md

Smart Interception - Implementation Complete

Date: 2026-01-06
Status: ✅ IMPLEMENTED

---

What Was Implemented

1. Added hasKey() Method to Web3SignerClient

File: src/clients/web3signer-client.ts

Added a new method to check if an address has a key loaded in Web3Signer:

async hasKey(address: string): Promise<boolean> {
  // Gets all public keys from Web3Signer
  // Checks if the address is in the list
  // Returns false if check fails (allows pass-through)
}

2. Modified RPC Handler for Smart Interception

File: src/handlers/rpc-handler.ts

Changes:

• Added Web3SignerClient as optional constructor parameter
• Modified handleInterceptedMethod() to check if address has key before intercepting
• If no key: Pass through to Besu (user wallet like MetaMask)
• If key exists: Intercept and sign via Web3Signer (service wallet)

Logic Flow:

eth_sendTransaction received
    ↓
Check if address has key in Web3Signer
    ↓
    ├─→ No key? → Pass through to Besu (user wallet)
    └─→ Has key? → Intercept and sign via Web3Signer (service wallet)

3. Updated Main Entry Point

File: src/main.ts

• Pass web3SignerClient to RpcHandler constructor
• Enables smart interception functionality

---

How It Works

For User Wallets (MetaMask)

1. User connects MetaMask wallet
2. Thirdweb SDK calls eth_sendTransaction
3. Translator checks: Does address have key in Web3Signer? NO
4. Translator passes through to Besu
5. Besu returns error (doesn't support unsigned transactions)
6. OR MetaMask signs locally and uses eth_sendRawTransaction (already works ✅)

For Service Wallets (Web3Signer)

1. Service wallet address has key in Web3Signer
2. Thirdweb SDK calls eth_sendTransaction (unsigned)
3. Translator checks: Does address have key in Web3Signer? YES
4. Translator intercepts and signs via Web3Signer
5. Translator converts to eth_sendRawTransaction
6. Translator submits to Besu ✅

---

Benefits

1. ✅ Automatic Detection: No manual allowlist configuration needed for user wallets
2. ✅ MetaMask Compatible: User wallets automatically pass through
3. ✅ Service Wallet Support: Service wallets still get signed via Web3Signer
4. ✅ Backward Compatible: Existing allowlist still works as additional security layer
5. ✅ Fail-Safe: If Web3Signer check fails, defaults to pass-through

---

Configuration

Allowlist Behavior

With Smart Interception:

• Allowlist is now optional for user wallets
• Allowlist still provides additional security for service wallets
• Empty allowlist = allow all (not recommended for production)
• Populated allowlist = only listed addresses can send transactions

Recommended:

• Keep allowlist with only service wallet addresses
• User wallets don't need to be in allowlist (they pass through automatically)

---

Testing

Test User Wallet (MetaMask)

# This should pass through to Besu
curl -X POST http://192.168.11.240:9545 \
  -H 'Content-Type: application/json' \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_sendTransaction",
    "params": [{
      "from": "0x71e81eaec98e507f68bbcf5e2005f179db851603",
      "to": "0x0000000000000000000000000000000000000000",
      "value": "0x0"
    }],
    "id": 1
  }'

Expected: Passes through to Besu (may return error from Besu if unsigned)

Test Service Wallet

# Get a service wallet address from Web3Signer
ADDRESS=$(curl -s http://192.168.11.111:9000/api/v1/eth1/publicKeys | jq -r '.[0]')

# This should be intercepted and signed
curl -X POST http://192.168.11.240:9545 \
  -H 'Content-Type: application/json' \
  -d "{
    \"jsonrpc\": \"2.0\",
    \"method\": \"eth_sendTransaction\",
    \"params\": [{
      \"from\": \"$ADDRESS\",
      \"to\": \"0x0000000000000000000000000000000000000000\",
      \"value\": \"0x0\"
    }],
    \"id\": 1
  }"

Expected: Intercepted, signed via Web3Signer, submitted to Besu

---

Deployment

Step 1: Build

cd /home/intlc/projects/proxmox/rpc-translator-138
pnpm run build

Step 2: Deploy to All VMIDs

./scripts/deploy-all-vmids.sh

Step 3: Verify

# Check logs for smart interception messages
ssh -i ~/.ssh/proxmox_translator root@192.168.11.240 "journalctl -u rpc-translator-138.service -n 50 --no-pager | grep -i 'has.*key\|pass.*through\|intercepting'"

---

Code Changes Summary

Files Modified

1. src/clients/web3signer-client.ts

   • Added hasKey(address: string): Promise<boolean> method

2. src/handlers/rpc-handler.ts

   • Added web3SignerClient?: Web3SignerClient parameter
   • Modified handleInterceptedMethod() with smart interception logic
   • Added key check before intercepting

3. src/main.ts

   • Pass web3SignerClient to RpcHandler constructor

4. src/interceptors/tx-interceptor.ts

   • Updated comment in validateTx() to reflect smart interception behavior

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Next Steps

1. Build the project: pnpm run build
2. Deploy to VMIDs: ./scripts/deploy-all-vmids.sh
3. Test with MetaMask: Connect MetaMask and send transaction
4. Test with service wallet: Send transaction from address with key in Web3Signer
5. Monitor logs: Check for smart interception messages

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Status: ✅ Smart interception implemented and ready for deployment!