Check the provided derivation path prefix

doc/APP_SPECIFICATION.md

@@ -195,9 +195,10 @@ The following standard Status Words are returned for all APDUs.
 |   B003   | SW_DISPLAY_AMOUNT_FAIL      | Amount conversion to string failed                    |
 |   B004   | SW_WRONG_TX_LENGTH          | Wrong raw transaction length                          |
 |   B005   | SW_TX_PARSING_FAIL          | Failed to parse raw transaction                       |
-|   B006   | SW_TX_HASH_FAIL          | Failed to compute hash digest of raw transaction      |
+|   B006   | SW_HASH_FAIL          | Failed to compute hash digest of raw transaction or msg      |
 |   B007   | SW_BAD_STATE                | Security issue with bad state                         |
 |   B008   | SW_SIGNATURE_FAIL           | Signature of data(tx or personal msg) failed            |
 |   B009   | SW_PERSONAL_MSG_PARSING_FAIL  | Failed to parse personal msg                            |
-|   B00A   | SW_PERSONAL_MSG_HASH_FAIL     | Failed to compute hash digest of personal msg           |
-|   B00B   | SW_INVALID_TRANSACTION  | Invalid transaction                              |
+|   B00A   | SW_INVALID_TRANSACTION  | Invalid transaction                              |
+|   B00B   | SW_HASH_FAILED  | Msg hash failed                              |
+|   B00C   | SW_INVALID_PATH  | Invalid path                              |

src/handler/get_public_key.c

@@ -32,6 +32,7 @@
 #include "sw.h"
 #include "display.h"
 #include "send_response.h"
+#include "../transaction/utils.h"
 
 int handler_get_public_key(buffer_t *cdata, bool display) {
     explicit_bzero(&G_context, sizeof(G_context));
@@ -43,6 +44,10 @@ int handler_get_public_key(buffer_t *cdata, bool display) {
         return io_send_sw(SW_WRONG_DATA_LENGTH);
     }
 
+    if (!is_valid_bip44_prefix(G_context.bip32_path, G_context.bip32_path_len)) {
+        return io_send_sw(SW_INVALID_PATH);
+    }
+
     cx_err_t error = bip32_derive_get_pubkey_256(CX_CURVE_256R1,
                                                  G_context.bip32_path,
                                                  G_context.bip32_path_len,

src/handler/sign_msg.c

@@ -43,13 +43,16 @@ int handler_sign_message(buffer_t *cdata, uint8_t chunk, bool more) {
                                     (size_t) G_context.bip32_path_len)) {
             return io_send_sw(SW_WRONG_DATA_LENGTH);
         }
+        if (!is_valid_bip44_prefix(G_context.bip32_path, G_context.bip32_path_len)) {
+            return io_send_sw(SW_INVALID_PATH);
+        }
         return io_send_sw(SW_OK);
     } else {
         if (G_context.req_type != CONFIRM_MESSAGE) {
             return io_send_sw(SW_BAD_STATE);
         }
         if (G_context.msg_info.raw_msg_len + cdata->size > sizeof(G_context.msg_info.raw_msg)) {
-            return io_send_sw(SW_WRONG_PERSONAL_MSG_LENGTH);
+            return io_send_sw(SW_WRONG_DATA_LENGTH);
         }
         if (!buffer_move(cdata,
                          G_context.msg_info.raw_msg + G_context.msg_info.raw_msg_len,
@@ -79,7 +82,7 @@ int handler_sign_message(buffer_t *cdata, uint8_t chunk, bool more) {
                                G_context.msg_info.raw_msg,
                                G_context.msg_info.raw_msg_len) != CX_OK ||
                 cx_hash_final((cx_hash_t *) &cx_sha256, G_context.msg_info.m_hash) != CX_OK) {
-                return io_send_sw(SW_WRONG_PERSONAL_MSG_LENGTH);  // todo, another sw
+                return io_send_sw(SW_HASH_FAIL);
             }
 
             PRINTF("Hash: %.*H\n", sizeof(G_context.msg_info.m_hash), G_context.msg_info.m_hash);

src/handler/sign_tx.c

@@ -47,6 +47,9 @@ int handler_sign_tx(buffer_t *cdata, uint8_t chunk, bool more) {
                                     (size_t) G_context.bip32_path_len)) {
             return io_send_sw(SW_WRONG_DATA_LENGTH);
         }
+        if (!is_valid_bip44_prefix(G_context.bip32_path, G_context.bip32_path_len)) {
+            return io_send_sw(SW_INVALID_PATH);
+        }
         return io_send_sw(SW_OK);
 
     } else {  // parse transaction
@@ -96,7 +99,7 @@ static int handler_hash_tx_and_display_tx(bool is_blind_signing) {
 
     explicit_bzero(&second_hash, sizeof(second_hash));
     if (!res) {
-        return io_send_sw(SW_TX_HASH_FAIL);
+        return io_send_sw(SW_HASH_FAIL);
     } else {
         G_context.state = STATE_PARSED;
         return ui_display_transaction(is_blind_signing);

src/sw.h

@@ -49,9 +49,9 @@
  */
 #define SW_TX_PARSING_FAIL 0xB005
 /**
- * Status word for fail of transaction hash.
+ * Status word for fail of hash.
  */
-#define SW_TX_HASH_FAIL 0xB006
+#define SW_HASH_FAIL 0xB006
 /**
  * Status word for bad state.
  */
@@ -65,10 +65,10 @@
  */
 #define SW_PERSONAL_MSG_PARSING_FAIL 0xB009
 /**
- * Status word for wrong personal msg length.
+ * Status word for invalid transaction.
  */
-#define SW_WRONG_PERSONAL_MSG_LENGTH 0xB00A
+#define SW_INVALID_TRANSACTION 0xB00A
 /**
- * Status word for invalid transaction.
+ * Status word for invalid path.
  */
-#define SW_INVALID_TRANSACTION 0xB00B
+#define SW_INVALID_PATH 0xB00B

src/transaction/utils.c

@@ -22,6 +22,9 @@
 #define P64_R              6                       // 2^64 % 10
 #define P64_Q              1844674407370955161ULL  // 2^64 / 10
 
+#define BIP44_COIN_TYPE_1024 0x80000400 // 1024' (hardened)
+#define BIP44_COIN_TYPE_888  0x80000378 // 888' (hardened)
+#define BIP44_PURPOSE        0x8000002C // 44' (hardened)
 static bool convert_bytes_to_uint64_le(const uint8_t *amount, const size_t len, uint64_t *out) {
     if (amount == NULL || out == NULL) {
         return false;
@@ -228,3 +231,12 @@ bool convert_param_amount_to_chars(tx_parameter_t *param,
             convert_params_to_uint128_le(param, has_prefix, &low, &high) &&
             format_fpu128_trimmed(amount, amount_len, low, high, decimals);
 }
+
+bool is_valid_bip44_prefix(uint32_t *path, uint8_t path_len) {
+    if (path_len < 2) { // Need at least purpose and coin type
+        return false;
+    }
+    // Check for 44' (purpose) followed by 1024' or 888' (coin type)
+    return path[0] == BIP44_PURPOSE &&
+           (path[1] == BIP44_COIN_TYPE_1024 || path[1] == BIP44_COIN_TYPE_888);
+}

src/transaction/utils.h

@@ -56,4 +56,16 @@ bool convert_param_amount_to_chars(tx_parameter_t *param,
  */
 static inline bool methodcmp(const tx_parameter_t *param, const char *method_name) {
     return param->len == strlen(method_name) && memcmp(param->data, method_name, param->len) == 0;
-}
+}
+
+/**
+ * Validate a BIP-32 path prefix (44'/1024' or 44'/888').
+ *
+ * @param[in] path
+ *   Pointer to the array representing the BIP-32 path.
+ * @param[in] path_len
+ *   Length of the path array.
+ *
+ * @return true if the path has a valid BIP-44 prefix, false otherwise.
+ */
+bool is_valid_bip44_prefix(uint32_t *path, uint8_t path_len);

tests/application_client/boilerplate_command_sender.py

@@ -43,12 +43,12 @@ class Errors(IntEnum):
     SW_DISPLAY_AMOUNT_FAIL     = 0xB003
     SW_WRONG_TX_LENGTH         = 0xB004
     SW_TX_PARSING_FAIL         = 0xB005
-    SW_TX_HASH_FAIL            = 0xB006
+    SW_HASH_FAIL            = 0xB006
     SW_BAD_STATE               = 0xB007
     SW_SIGNATURE_FAIL          = 0xB008
     SW_PERSONAL_MSG_PARSING_FAIL = 0xB009
-    SW_WRONG_PERSONAL_MSG_LENGTH = 0xB00A
-    SW_INVALID_TRANSACTION     = 0xB00B
+    SW_INVALID_TRANSACTION     = 0xB00A
+    SW_INVALID_PATH           = 0xB00B
 
 
 def split_message(message: bytes, max_size: int) -> List[bytes]: