Mifare Classic nested auth support (#3238)

Co-authored-by: Aleksandr Kutuzov <alleteam@gmail.com>

lib/nfc/protocols/mf_classic/crypto1.c

@@ -143,7 +143,8 @@ void crypto1_encrypt_reader_nonce(
     uint32_t cuid,
     uint8_t* nt,
     uint8_t* nr,
-    BitBuffer* out) {
+    BitBuffer* out,
+    bool is_nested) {
     furi_assert(crypto);
     furi_assert(nt);
     furi_assert(nr);
@@ -153,7 +154,11 @@ void crypto1_encrypt_reader_nonce(
     uint32_t nt_num = nfc_util_bytes2num(nt, sizeof(uint32_t));
 
     crypto1_init(crypto, key);
-    crypto1_word(crypto, nt_num ^ cuid, 0);
+    if(is_nested) {
+        nt_num = crypto1_word(crypto, nt_num ^ cuid, 1) ^ nt_num;
+    } else {
+        crypto1_word(crypto, nt_num ^ cuid, 0);
+    }
 
     for(size_t i = 0; i < 4; i++) {
         uint8_t byte = crypto1_byte(crypto, nr[i], 0) ^ nr[i];

lib/nfc/protocols/mf_classic/crypto1.h

@@ -35,7 +35,8 @@ void crypto1_encrypt_reader_nonce(
     uint32_t cuid,
     uint8_t* nt,
     uint8_t* nr,
-    BitBuffer* out);
+    BitBuffer* out,
+    bool is_nested);
 
 uint32_t prng_successor(uint32_t x, uint32_t n);
 

lib/nfc/protocols/mf_classic/mf_classic_poller.h

@@ -178,6 +178,25 @@ MfClassicError mf_classic_poller_get_nt(
     MfClassicKeyType key_type,
     MfClassicNt* nt);
 
+/**
+ * @brief Collect tag nonce during nested authentication.
+ *
+ * Must ONLY be used inside the callback function.
+ *
+ * Starts nested authentication procedure and collects tag nonce.
+ *
+ * @param[in, out] instance pointer to the instance to be used in the transaction.
+ * @param[in] block_num block number for authentication.
+ * @param[in] key_type key type to be used for authentication.
+ * @param[out] nt pointer to the MfClassicNt structure to be filled with nonce data.
+ * @return MfClassicErrorNone on success, an error code on failure.
+ */
+MfClassicError mf_classic_poller_get_nt_nested(
+    MfClassicPoller* instance,
+    uint8_t block_num,
+    MfClassicKeyType key_type,
+    MfClassicNt* nt);
+
 /**
  * @brief Perform authentication.
  *
@@ -200,6 +219,27 @@ MfClassicError mf_classic_poller_auth(
     MfClassicKeyType key_type,
     MfClassicAuthContext* data);
 
+/**
+ * @brief Perform nested authentication.
+ *
+ * Must ONLY be used inside the callback function.
+ *
+ * Perform nested  authentication as specified in Mf Classic protocol.
+ *
+ * @param[in, out] instance pointer to the instance to be used in the transaction.
+ * @param[in] block_num block number for authentication.
+ * @param[in] key key to be used for authentication.
+ * @param[in] key_type key type to be used for authentication.
+ * @param[out] data pointer to MfClassicAuthContext structure to be filled with authentication data.
+ * @return MfClassicErrorNone on success, an error code on failure.
+ */
+MfClassicError mf_classic_poller_auth_nested(
+    MfClassicPoller* instance,
+    uint8_t block_num,
+    MfClassicKey* key,
+    MfClassicKeyType key_type,
+    MfClassicAuthContext* data);
+
 /**
  * @brief Halt the tag.
  *

lib/nfc/protocols/mf_classic/mf_classic_poller_i.c

@@ -33,11 +33,12 @@ MfClassicError mf_classic_process_error(Iso14443_3aError error) {
     return ret;
 }
 
-MfClassicError mf_classic_poller_get_nt(
+static MfClassicError mf_classic_poller_get_nt_common(
     MfClassicPoller* instance,
     uint8_t block_num,
     MfClassicKeyType key_type,
-    MfClassicNt* nt) {
+    MfClassicNt* nt,
+    bool is_nested) {
     MfClassicError ret = MfClassicErrorNone;
     Iso14443_3aError error = Iso14443_3aErrorNone;
 
@@ -47,14 +48,29 @@ MfClassicError mf_classic_poller_get_nt(
         uint8_t auth_cmd[2] = {auth_type, block_num};
         bit_buffer_copy_bytes(instance->tx_plain_buffer, auth_cmd, sizeof(auth_cmd));
 
-        error = iso14443_3a_poller_send_standard_frame(
-            instance->iso14443_3a_poller,
-            instance->tx_plain_buffer,
-            instance->rx_plain_buffer,
-            MF_CLASSIC_FWT_FC);
-        if(error != Iso14443_3aErrorWrongCrc) {
-            ret = mf_classic_process_error(error);
-            break;
+        if(is_nested) {
+            iso14443_crc_append(Iso14443CrcTypeA, instance->tx_plain_buffer);
+            crypto1_encrypt(
+                instance->crypto, NULL, instance->tx_plain_buffer, instance->tx_encrypted_buffer);
+            error = iso14443_3a_poller_txrx_custom_parity(
+                instance->iso14443_3a_poller,
+                instance->tx_encrypted_buffer,
+                instance->rx_plain_buffer, // NT gets decrypted by mf_classic_async_auth
+                MF_CLASSIC_FWT_FC);
+            if(error != Iso14443_3aErrorNone) {
+                ret = mf_classic_process_error(error);
+                break;
+            }
+        } else {
+            error = iso14443_3a_poller_send_standard_frame(
+                instance->iso14443_3a_poller,
+                instance->tx_plain_buffer,
+                instance->rx_plain_buffer,
+                MF_CLASSIC_FWT_FC);
+            if(error != Iso14443_3aErrorWrongCrc) {
+                ret = mf_classic_process_error(error);
+                break;
+            }
         }
         if(bit_buffer_get_size_bytes(instance->rx_plain_buffer) != sizeof(MfClassicNt)) {
             ret = MfClassicErrorProtocol;
@@ -69,12 +85,29 @@ MfClassicError mf_classic_poller_get_nt(
     return ret;
 }
 
-MfClassicError mf_classic_poller_auth(
+MfClassicError mf_classic_poller_get_nt(
+    MfClassicPoller* instance,
+    uint8_t block_num,
+    MfClassicKeyType key_type,
+    MfClassicNt* nt) {
+    return mf_classic_poller_get_nt_common(instance, block_num, key_type, nt, false);
+}
+
+MfClassicError mf_classic_poller_get_nt_nested(
+    MfClassicPoller* instance,
+    uint8_t block_num,
+    MfClassicKeyType key_type,
+    MfClassicNt* nt) {
+    return mf_classic_poller_get_nt_common(instance, block_num, key_type, nt, true);
+}
+
+static MfClassicError mf_classic_poller_auth_common(
     MfClassicPoller* instance,
     uint8_t block_num,
     MfClassicKey* key,
     MfClassicKeyType key_type,
-    MfClassicAuthContext* data) {
+    MfClassicAuthContext* data,
+    bool is_nested) {
     MfClassicError ret = MfClassicErrorNone;
     Iso14443_3aError error = Iso14443_3aErrorNone;
 
@@ -84,7 +117,11 @@ MfClassicError mf_classic_poller_auth(
             iso14443_3a_poller_get_data(instance->iso14443_3a_poller));
 
         MfClassicNt nt = {};
-        ret = mf_classic_poller_get_nt(instance, block_num, key_type, &nt);
+        if(is_nested) {
+            ret = mf_classic_poller_get_nt_nested(instance, block_num, key_type, &nt);
+        } else {
+            ret = mf_classic_poller_get_nt(instance, block_num, key_type, &nt);
+        }
         if(ret != MfClassicErrorNone) break;
         if(data) {
             data->nt = nt;
@@ -96,7 +133,13 @@ MfClassicError mf_classic_poller_auth(
         furi_hal_random_fill_buf(nr.data, sizeof(MfClassicNr));
 
         crypto1_encrypt_reader_nonce(
-            instance->crypto, key_num, cuid, nt.data, nr.data, instance->tx_encrypted_buffer);
+            instance->crypto,
+            key_num,
+            cuid,
+            nt.data,
+            nr.data,
+            instance->tx_encrypted_buffer,
+            is_nested);
         error = iso14443_3a_poller_txrx_custom_parity(
             instance->iso14443_3a_poller,
             instance->tx_encrypted_buffer,
@@ -130,6 +173,24 @@ MfClassicError mf_classic_poller_auth(
     return ret;
 }
 
+MfClassicError mf_classic_poller_auth(
+    MfClassicPoller* instance,
+    uint8_t block_num,
+    MfClassicKey* key,
+    MfClassicKeyType key_type,
+    MfClassicAuthContext* data) {
+    return mf_classic_poller_auth_common(instance, block_num, key, key_type, data, false);
+}
+
+MfClassicError mf_classic_poller_auth_nested(
+    MfClassicPoller* instance,
+    uint8_t block_num,
+    MfClassicKey* key,
+    MfClassicKeyType key_type,
+    MfClassicAuthContext* data) {
+    return mf_classic_poller_auth_common(instance, block_num, key, key_type, data, true);
+}
+
 MfClassicError mf_classic_poller_halt(MfClassicPoller* instance) {
     MfClassicError ret = MfClassicErrorNone;
     Iso14443_3aError error = Iso14443_3aErrorNone;

targets/f18/api_symbols.csv

@@ -1,5 +1,5 @@
 entry,status,name,type,params
-Version,+,49.0,,
+Version,+,49.1,,
 Header,+,applications/services/bt/bt_service/bt.h,,
 Header,+,applications/services/cli/cli.h,,
 Header,+,applications/services/cli/cli_vcp.h,,

targets/f7/api_symbols.csv

@@ -1,5 +1,5 @@
 entry,status,name,type,params
-Version,+,49.0,,
+Version,+,49.1,,
 Header,+,applications/drivers/subghz/cc1101_ext/cc1101_ext_interconnect.h,,
 Header,+,applications/services/bt/bt_service/bt.h,,
 Header,+,applications/services/cli/cli.h,,
@@ -2288,6 +2288,8 @@ Function,+,mf_classic_is_sector_trailer,_Bool,uint8_t
 Function,+,mf_classic_is_value_block,_Bool,"MfClassicSectorTrailer*, uint8_t"
 Function,+,mf_classic_load,_Bool,"MfClassicData*, FlipperFormat*, uint32_t"
 Function,+,mf_classic_poller_auth,MfClassicError,"MfClassicPoller*, uint8_t, MfClassicKey*, MfClassicKeyType, MfClassicAuthContext*"
+Function,+,mf_classic_poller_auth_nested,MfClassicError,"MfClassicPoller*, uint8_t, MfClassicKey*, MfClassicKeyType, MfClassicAuthContext*"
+Function,+,mf_classic_poller_get_nt_nested,MfClassicError,"MfClassicPoller*, uint8_t, MfClassicKeyType, MfClassicNt*"
 Function,+,mf_classic_poller_get_nt,MfClassicError,"MfClassicPoller*, uint8_t, MfClassicKeyType, MfClassicNt*"
 Function,+,mf_classic_poller_halt,MfClassicError,MfClassicPoller*
 Function,+,mf_classic_poller_read_block,MfClassicError,"MfClassicPoller*, uint8_t, MfClassicBlock*"