From 78a9ab8123122314042f65d86928442fa8a74761 Mon Sep 17 00:00:00 2001
From: Andrew Kozlik <andrew.kozlik@gmail.com>
Date: Fri, 15 Oct 2021 16:43:44 +0200
Subject: [PATCH] feat(legacy): Add BIP86 paths to coin_path_check().

---
 legacy/firmware/crypto.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/legacy/firmware/crypto.c b/legacy/firmware/crypto.c
index 139975a157..e1ffc439fd 100644
--- a/legacy/firmware/crypto.c
+++ b/legacy/firmware/crypto.c
@@ -655,6 +655,7 @@ bool coin_path_check(const CoinInfo *coin, InputScriptType script_type,
     valid = valid && check_cointype(coin, address_n[1], check_known);
     if (check_script_type) {
       valid = valid && has_multisig;
+      // we do not support Multisig with Taproot yet
       valid = valid && (script_type == InputScriptType_SPENDMULTISIG ||
                         script_type == InputScriptType_SPENDP2SHWITNESS ||
                         script_type == InputScriptType_SPENDWITNESS);
@@ -722,6 +723,31 @@ bool coin_path_check(const CoinInfo *coin, InputScriptType script_type,
     return valid;
   }
 
+  // m/86' : BIP86 Taproot
+  // m / purpose' / coin_type' / account' / change / address_index
+  if (address_n_count > 0 && address_n[0] == (0x80000000 + 86)) {
+    valid = valid && coin->has_taproot;
+    valid = valid && (coin->bech32_prefix != NULL);
+    if (check_known) {
+      valid = valid && (address_n_count == 5);
+    } else {
+      valid = valid && (address_n_count >= 2);
+    }
+    valid = valid && check_cointype(coin, address_n[1], check_known);
+    if (check_script_type) {
+      // we do not support Multisig with Taproot yet
+      valid = valid && !has_multisig;
+      valid = valid && (script_type == InputScriptType_SPENDTAPROOT);
+    }
+    if (check_known) {
+      valid = valid && ((address_n[2] & 0x80000000) == 0x80000000);
+      valid = valid && ((address_n[2] & 0x7fffffff) <= PATH_MAX_ACCOUNT);
+      valid = valid && (address_n[3] <= PATH_MAX_CHANGE);
+      valid = valid && (address_n[4] <= PATH_MAX_ADDRESS_INDEX);
+    }
+    return valid;
+  }
+
   // Green Address compatibility pattern. Will be removed in the future.
   // m / [1,4] / address_index
   if (address_n_count > 0 && (address_n[0] == 1 || address_n[0] == 4)) {