diff --git a/Makefile b/Makefile
index ae419c66..14bca79c 100644
--- a/Makefile
+++ b/Makefile
@@ -65,6 +65,7 @@ endif
 
 ENABLE_BLUETOOTH = 1
 ENABLE_NBGL_QRCODE = 1
+ENABLE_SWAP = 1
 
 ifeq ($(TARGET_NAME),TARGET_STAX)
 DEFINES += COIN_ICON=C_$(COIN)_64px
diff --git a/src/btchip_display_variables.h b/src/btchip_display_variables.h
index f62263cb..694d3a51 100644
--- a/src/btchip_display_variables.h
+++ b/src/btchip_display_variables.h
@@ -1,3 +1,4 @@
+#include "os.h"
 #ifndef _BTCHIP_DISPLAY_VARIABLES_H_
 #define _BTCHIP_DISPLAY_VARIABLES_H_
 
@@ -12,6 +13,7 @@ typedef struct swap_data_s {
         // number of already signed input in the transaction, to compare with
         // totalNumberOfInputs and exit properly
         int alreadySignedInputs;
+        int initialized;
         unsigned char amount[8];
         unsigned char fees[8];
         char destination_address[65];
diff --git a/src/handle_check_address.c b/src/handle_check_address.c
index b7dcde7d..41a8b730 100644
--- a/src/handle_check_address.c
+++ b/src/handle_check_address.c
@@ -81,26 +81,42 @@ static bool get_address_from_compressed_public_key(
     return true;
 }
 
-static int os_strcmp(const char* s1, const char* s2) {
-    size_t size = strlen(s1) + 1;
-    return memcmp(s1, s2, size);
-}
+void swap_handle_check_address(check_address_parameters_t* params) {
+    PRINTF("Inside swap_handle_check_address\n");
+    params->result = 0;
+
+    if (params->address_parameters == NULL) {
+        PRINTF("derivation path expected\n");
+        return;
+    }
+
+    if (params->address_to_check == NULL) {
+        PRINTF("Address to check expected\n");
+        return;
+    }
+    PRINTF("Address to check %s\n", params->address_to_check);
+
+    if (params->extra_id_to_check == NULL) {
+        PRINTF("extra_id_to_check expected\n");
+        return;
+    } else if (params->extra_id_to_check[0] != '\0') {
+        PRINTF("extra_id_to_check expected empty, not '%s'\n", params->extra_id_to_check);
+        return;
+    }
 
-int handle_check_address(check_address_parameters_t* params) {
-    unsigned char compressed_public_key[33];
-    PRINTF("Params on the address %d\n",(unsigned int)params);
-    PRINTF("Address to check %s\n",params->address_to_check);
-    PRINTF("Inside handle_check_address\n");
     if (params->address_to_check == 0) {
         PRINTF("Address to check == 0\n");
-        return 0;
+        return;
     }
+
+    unsigned char compressed_public_key[33];
     if (!derive_compressed_public_key(
         params->address_parameters + 1,
         params->address_parameters_length - 1,
         compressed_public_key,
         sizeof(compressed_public_key))) {
-        return 0;
+        PRINTF("Failed to derive public key\n");
+        return;
     }
 
     char address[51];
@@ -113,12 +129,16 @@ int handle_check_address(check_address_parameters_t* params) {
         address,
         sizeof(address))) {
         PRINTF("Can't create address from given public key\n");
-        return 0;
+        return;
     }
-    if (os_strcmp(address,params->address_to_check) != 0) {
-        PRINTF("Addresses don't match\n");
-        return 0;
+
+    if (strcmp(params->address_to_check, address) != 0) {
+        PRINTF("Address %s != %s\n", params->address_to_check, address);
+        return;
     }
+
     PRINTF("Addresses match\n");
-    return 1;
+
+    params->result = 1;
+    return;
 }
\ No newline at end of file
diff --git a/src/handle_check_address.h b/src/handle_check_address.h
index 4d6c2a63..59806838 100644
--- a/src/handle_check_address.h
+++ b/src/handle_check_address.h
@@ -4,6 +4,6 @@
 #include "swap_lib_calls.h"
 #include "btchip_context.h"
 
-int handle_check_address(check_address_parameters_t* check_address_params);
+void handle_check_address(check_address_parameters_t* check_address_params);
 
 #endif // _HANDLE_CHECK_ADDRESS_H_
\ No newline at end of file
diff --git a/src/handle_get_printable_amount.c b/src/handle_get_printable_amount.c
index 2be91eef..9d4e9e4d 100644
--- a/src/handle_get_printable_amount.c
+++ b/src/handle_get_printable_amount.c
@@ -2,11 +2,11 @@
 #include "btchip_bcd.h"
 #include <string.h>
 
-int handle_get_printable_amount(get_printable_amount_parameters_t* params) {
+void swap_handle_get_printable_amount(get_printable_amount_parameters_t* params) {
     params->printable_amount[0] = 0;
     if (params->amount_length > 8) {
         PRINTF("Amount is too big");
-        return 0;
+        return;
     }
     unsigned char amount[8];
     memset(amount, 0, 8);
@@ -17,5 +17,5 @@ int handle_get_printable_amount(get_printable_amount_parameters_t* params) {
     int res_length = btchip_convert_hex_amount_to_displayable_no_globals(amount, COIN_FLAGS, (uint8_t *)params->printable_amount + coin_name_length + 1);
     params->printable_amount[res_length + coin_name_length + 1] = '\0';
 
-    return 1;
+    return;
 }
\ No newline at end of file
diff --git a/src/handle_get_printable_amount.h b/src/handle_get_printable_amount.h
index a870dbdd..5b9ba487 100644
--- a/src/handle_get_printable_amount.h
+++ b/src/handle_get_printable_amount.h
@@ -4,6 +4,6 @@
 #include "swap_lib_calls.h"
 #include "btchip_context.h"
 
-int handle_get_printable_amount(get_printable_amount_parameters_t* get_printable_amount_params);
+void swap_handle_get_printable_amount(get_printable_amount_parameters_t* get_printable_amount_params);
 
 #endif // _HANDLE_GET_PRINTABLE_AMOUNT_H_
\ No newline at end of file
diff --git a/src/handle_swap_sign_transaction.c b/src/handle_swap_sign_transaction.c
index 92160215..6ecbdca9 100644
--- a/src/handle_swap_sign_transaction.c
+++ b/src/handle_swap_sign_transaction.c
@@ -10,37 +10,65 @@
 #include "nbgl_use_case.h"
 #endif
 
+#include "swap.h"
+
 // Save the BSS address where we will write the return value when finished
 static uint8_t *G_swap_sign_return_value_address;
 
-bool copy_transaction_parameters(create_transaction_parameters_t* sign_transaction_params) {
-    // first copy parameters to stack, and then to global data.
-    // We need this "trick" as the input data position can overlap with btc-app globals
-    swap_data_t stack_data;
-    memset(&stack_data, 0, sizeof(stack_data));
-    strncpy(stack_data.destination_address, sign_transaction_params->destination_address, sizeof(stack_data.destination_address) - 1);
-    if ((stack_data.destination_address[sizeof(stack_data.destination_address) - 1] != '\0') ||
-        (sign_transaction_params->amount_length > 8) ||
-        (sign_transaction_params->fee_amount_length > 8)) {
+bool swap_copy_transaction_parameters(create_transaction_parameters_t* params) {
+    PRINTF("Inside swap_copy_transaction_parameters\n");
+
+    // Ensure no extraid
+    if (params->destination_address_extra_id == NULL) {
+        PRINTF("destination_address_extra_id expected\n");
+        return false;
+    } else if (params->destination_address_extra_id[0] != '\0') {
+        PRINTF("destination_address_extra_id expected empty, not '%s'\n",
+               params->destination_address_extra_id);
+        return false;
+    }
+
+    // We need this "trick" as the input data position can overlap with app globals
+    // and also because we want to memset the whole bss segment as it is not done
+    // when an app is called as a lib.
+    // This is necessary as many part of the code expect bss variables to
+    // initialized at 0.
+    swap_data_t swap_validated;
+    memset(&swap_validated, 0, sizeof(swap_validated));
+
+    // Save recipient
+    strlcpy(swap_validated.destination_address,
+            params->destination_address, 
+            sizeof(swap_validated.destination_address));
+    if (swap_validated.destination_address[sizeof(swap_validated.destination_address) - 1] != '\0') {
         return false;
     }
+
     // store amount as big endian in 8 bytes, so the passed data should be alligned to right
     // input {0xEE, 0x00, 0xFF} should be stored like {0x00, 0x00, 0x00, 0x00, 0x00, 0xEE, 0x00, 0xFF}
-    memcpy(stack_data.amount + 8 - sign_transaction_params->amount_length, sign_transaction_params->amount, sign_transaction_params->amount_length);
-    memcpy(stack_data.fees + 8 - sign_transaction_params->fee_amount_length, sign_transaction_params->fee_amount, sign_transaction_params->fee_amount_length);
+    memcpy(swap_validated.amount + 8 - params->amount_length, params->amount, params->amount_length);
+    memcpy(swap_validated.fees + 8 - params->fee_amount_length, params->fee_amount, params->fee_amount_length);
 
-    // Erase values inherited from Exchange app
+    // Save amount and fees
+//    swap_str_to_u64(params->amount, params->amount_length, &swap_validated.amount);
+//    swap_str_to_u64(params->fee_amount, params->fee_amount_length, &swap_validated.fees);
+//
+    swap_validated.initialized = true;
+
+    // Full reset the global variables
     os_explicit_zero_BSS_segment();
 
     // Keep the address at which we'll reply the signing status
-    G_swap_sign_return_value_address = &sign_transaction_params->result;
+    G_swap_sign_return_value_address = &params->result;
+
 
     // Copy from stack back to global data segment
-    memcpy(&vars.swap_data, &stack_data, sizeof(stack_data));
+    memcpy(&vars.swap_data, &swap_validated, sizeof(swap_validated));
+    swap_validated.initialized = true;
     return true;
 }
 
-void handle_swap_sign_transaction(void) {
+void swap_handle_swap_sign_transaction(void) {
     btchip_context_init();
     io_seproxyhal_init();
     UX_INIT();
diff --git a/src/handle_swap_sign_transaction.h b/src/handle_swap_sign_transaction.h
index 91978797..0f9bc0bc 100644
--- a/src/handle_swap_sign_transaction.h
+++ b/src/handle_swap_sign_transaction.h
@@ -4,9 +4,9 @@
 #include "swap_lib_calls.h"
 #include "btchip_context.h"
 
-bool copy_transaction_parameters(create_transaction_parameters_t* sign_transaction_params);
+bool swap_copy_transaction_parameters(create_transaction_parameters_t* sign_transaction_params);
 
-void handle_swap_sign_transaction(void);
+void swap_handle_swap_sign_transaction(void);
 
 void __attribute__((noreturn)) finalize_exchange_sign_transaction(bool is_success);