protect: Add "Nonce Management" page to document eth_getTransactionCount behavior. (#573)

Author: ryanschneider

docs/flashbots-protect/nonce-management.mdx

@@ -0,0 +1,85 @@
+---
+title: Nonce Management
+---
+
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+Normally, a wallet can call `eth_getTransactionCount` to get the next nonce to use for a transaction.
+However, since transactions sent to Flashbots Protect are potentially sensitive, even exposing the incremented nonce can leak information about the user's activity.
+
+As such, transactions sent to Flashbots Protect are only included in the `eth_getTransactionCount` results when querying the `"pending"` nonce, and only if the request is signed by the user's private key.
+
+This is done by sending a JSON-RPC request to the Flashbots Protect RPC endpoint with the following parameters:
+
+```json
+{
+  "jsonrpc": "2.0",
+  "method": "eth_getTransactionCount",
+  "params": [
+    "0xYOUR_ADDRESS",
+    "pending"
+  ],
+  "id": 1
+}
+```
+
+The request is then signed and the signature is included in the `X-Flashbots-Signature` header. Without such a signature, the returned nonce will only include transactions sent to the public mempool.
+
+### Authentication
+
+To authenticate your request, sign the payload and include the signed payload in the `X-Flashbots-Signature` header of your request.
+
+```curl
+curl -X POST -H "Content-Type: application/json" -H "X-Flashbots-Signature: <public key address>:<signature>" --data '{"jsonrpc":"2.0","method":"eth_getTransactionCount","params":["0xYOUR_ADDRESS","pending"],"id":1}' https://rpc.flashbots.net
+```
+
+The private key of the address your want to query must be used to sign the payload.
+
+The signature is calculated by taking the [EIP-191](https://eips.ethereum.org/EIPS/eip-191) hash of the json body encoded as UTF-8 bytes. Here's an example using ethers.js:
+
+<Tabs
+defaultValue="ethers.js"
+values={[
+{ label: 'ethers.js', value: 'ethers.js', },
+{ label: 'web3.py', value: 'web3.py' },
+{ label: 'go', value: 'go' },
+]}
+>
+<TabItem value="ethers.js">
+
+```ts
+import {Wallet, utils} from 'ethers';
+
+const privateKey = '0x1234';
+const wallet = new Wallet(privateKey);
+const body =
+  '{"jsonrpc":"2.0","method":"eth_getTransactionCount","params":["0xYOUR_ADDRESS","pending"],"id":1}';
+const signature = wallet.address + ':' + wallet.signMessage(utils.id(body));
+```
+
+</TabItem>
+<TabItem value="web3.py">
+
+```py
+from web3 import Web3
+from eth_account import Account, messages
+
+body = '{"jsonrpc":"2.0","method":"eth_getTransactionCount","params":["0xYOUR_ADDRESS","pending"],"id":1}'
+message = messages.encode_defunct(text=Web3.keccak(text=body).hex())
+signature = Account.from_key(private_key).address + ':' + Account.sign_message(message, private_key).signature.hex()
+```
+
+</TabItem>
+<TabItem value="go">
+
+```go
+body := `{"jsonrpc":"2.0","method":"eth_getTransactionCount","params":["0xYOUR_ADDRESS","pending"],"id":1}`
+hashedBody := crypto.Keccak256Hash([]byte(body)).Hex()
+sig, err := crypto.Sign(accounts.TextHash([]byte(hashedBody)), privKey)
+signature := crypto.PubkeyToAddress(privKey.PublicKey).Hex() + ":" + hexutil.Encode(sig)
+```
+
+</TabItem>
+</Tabs>
+

docs/sidebars.js

@@ -56,6 +56,7 @@ module.exports = {
         'flashbots-protect/mev-share',
         'flashbots-protect/gas-fee-refunds',
         'flashbots-protect/cancellations',
+        'flashbots-protect/nonce-management',
         'flashbots-protect/stuck_transactions',
         'flashbots-protect/large-transactions',
         {