From be688217c015c36ee0d4ac3d79d8521a16eab3fc Mon Sep 17 00:00:00 2001
From: Nathan Woodburn <github@nathan.woodburn.au>
Date: Sun, 26 Jan 2025 12:16:17 +1100
Subject: [PATCH] feat: add find address

---
 find-address.js | 56 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 find-address.js

diff --git a/find-address.js b/find-address.js
new file mode 100644
index 0000000..000c2c4
--- /dev/null
+++ b/find-address.js
@@ -0,0 +1,56 @@
+/**
+ * This script finds an address given an account extended public key
+ * Usage: edit these fields below and run it like `node find-address.js`
+ */
+
+const assert = require('node:assert/strict');
+const HDPublicKey = require('hsd/lib/hd/public');
+const Address = require('hsd/lib/primitives/address');
+
+// **********
+// FILL THESE
+// **********
+const NETWORK = 'main';
+const ACCOUNT_XPUB = 'xpub6BvF6DnLZRV6my62FuQ8nw5TRebL8qr9Wa7u2tE1aEedHWBt4XAfSaNTmP1SM2nXErGWSzxRAHVwqstPzRrsXtA2vn1a4KzLwAVEgLNmfca'; // should start with: xpub, rpub, etc.
+const SEARCH_ADDRESS = 'hs1q3tlnmk9sp2luxdvkdcyvtj8ucj5pa4hwvr8ql6';
+
+const [START, END] = [0, 0x7fffffff];
+// const [START, END] = [0, 100];
+
+(() => {
+  const account = HDPublicKey.fromBase58(ACCOUNT_XPUB, NETWORK);
+  console.log('[*] Using account public key:', account.xpubkey(NETWORK));
+
+  const expectedAddr = new Address(SEARCH_ADDRESS, NETWORK);
+  console.log('[*] Searching for address:', expectedAddr.toString(NETWORK));
+
+  const len = END - START;
+  assert((len >>> 0) > 0);
+
+  for (let i = START; i <= END; i++) {
+    if (i % 1e3 === 0) {
+      console.log(`[${i}/${len}] searching...`);
+    }
+
+    /** @type {Buffer[]} */
+    const keys = [
+      account.derive(0).derive(i).publicKey, // receive
+      account.derive(1).derive(i).publicKey, // change
+    ];
+
+    for (const [branch, key] of keys.entries()) {
+      const addr = Address.fromPubkey(key);
+      if (expectedAddr.equals(addr)) {
+        console.log('Found address', {
+          address: addr,
+          branch: branch,
+          index: i,
+          publicKey: key.toString('hex'),
+        });
+        return;
+      }
+    }
+  }
+
+  console.log(`Searched index from ${START} to ${END}. Address not found.`);
+})();
\ No newline at end of file