diff --git a/file.c b/file.c
index 2853cb2..96d4c5a 100644
--- a/file.c
+++ b/file.c
@@ -2,6 +2,7 @@
 #include "gnuk.h"
 #include "tusb.h"
 #include "hsm2040.h"
+#include "sc_hsm.h"
 #include <string.h>
 
 extern const uintptr_t end_data_pool;
@@ -185,6 +186,26 @@ bool authenticate_action(const file_t *ef, uint8_t op) {
 
 #include "libopensc/pkcs15.h"
 
+int reset_pin_retries(const file_t *pin) {
+    if (!pin)
+        return HSM_ERR_NULL_PARAM; 
+    const file_t *max = search_by_fid(pin->fid+1, NULL, SPECIFY_EF);
+    const file_t *act = search_by_fid(pin->fid+2, NULL, SPECIFY_EF);
+    if (!max || !act)
+        return HSM_ERR_FILE_NOT_FOUND;
+    return flash_write_data_to_file((file_t *)act, &max->data[2], sizeof(uint8_t));
+}
+
+int pin_wrong_retry(const file_t *pin) {
+    if (!pin)
+        return HSM_ERR_NULL_PARAM; 
+    const file_t *act = search_by_fid(pin->fid+2, NULL, SPECIFY_EF);
+    if (!act)
+        return HSM_ERR_FILE_NOT_FOUND;
+    if (act->data[2] > 0)
+        return flash_write_data_to_file((file_t *)act, &act->data[2]-1, sizeof(uint8_t));
+    return HSM_ERR_BLOCKED;
+}
 
 void scan_flash() {
     if (*(uintptr_t *)end_data_pool == 0xffffffff && *(uintptr_t *)(end_data_pool+sizeof(uintptr_t)) == 0xffffffff) 
@@ -326,4 +347,4 @@ void scan_flash() {
         TU_LOG1("FATAL ERROR: Retries SOPIN not found in memory!\r\n");
     }
     low_flash_available();
-}
\ No newline at end of file
+}
diff --git a/hsm2040.h b/hsm2040.h
index 4ae85b7..18a1cf0 100644
--- a/hsm2040.h
+++ b/hsm2040.h
@@ -9,6 +9,7 @@
 
 #include "ccid.h"
 #include "tusb.h"
+#include "file.h"
 
 #define USB_REQ_CCID        0xA1
 
@@ -108,6 +109,8 @@ void put_binary (const char *s, int len);
 #define DEBUG_BINARY(s,len)
 #endif
 
+extern int flash_write_data_to_file(file_t *file, const uint8_t *data, uint16_t len);
+
 
 
 #endif
\ No newline at end of file
diff --git a/low_flash.c b/low_flash.c
index 61e4f0c..eb7719f 100644
--- a/low_flash.c
+++ b/low_flash.c
@@ -10,6 +10,7 @@
 #include "pico/multicore.h"
 #include "gnuk.h"
 #include "hsm2040.h"
+#include "sc_hsm.h"
 #include <string.h>
 
 #define TOTAL_FLASH_PAGES 4
@@ -135,18 +136,18 @@ int flash_program_block(uintptr_t addr, const uint8_t *data, size_t len) {
     if (ready_pages == TOTAL_FLASH_PAGES) {
         mutex_exit(&mtx_flash);
         DEBUG_INFO("ERROR: ALL FLASH PAGES CACHED\r\n");
-        return 1;
+        return HSM_ERR_NO_MEMORY;
     }
     if (!(p = find_free_page(addr)))
     {
         DEBUG_INFO("ERROR: FLASH CANNOT FIND A PAGE (rare error)\r\n");
         mutex_exit(&mtx_flash);
-        return 1;
+        return HSM_ERR_MEMORY_FATAL;
     }
     memcpy(&p->page[addr&(FLASH_SECTOR_SIZE-1)], data, len);
     //printf("Flash: modified page %X with data %x at [%x] (top page %X)\r\n",addr_alg,data,addr&(FLASH_SECTOR_SIZE-1),addr);
     mutex_exit(&mtx_flash);
-    return 0;
+    return HSM_OK;
 }
 
 int flash_program_halfword (uintptr_t addr, uint16_t data)
@@ -208,30 +209,29 @@ int flash_erase_page (uintptr_t addr, size_t page_size)
     if (ready_pages == TOTAL_FLASH_PAGES) {
         mutex_exit(&mtx_flash);
         DEBUG_INFO("ERROR: ALL FLASH PAGES CACHED\r\n");
-        return 1;
+        return HSM_ERR_NO_MEMORY;
     }
     if (!(p = find_free_page(addr)))
     {
         DEBUG_INFO("ERROR: FLASH CANNOT FIND A PAGE (rare error)\r\n");
         mutex_exit(&mtx_flash);
-        return 1;
+        return HSM_ERR_MEMORY_FATAL;
     }
     p->erase = true;
     p->ready = false;
     p->page_size = page_size;
     mutex_exit(&mtx_flash);
     
-    return 0;
+    return HSM_OK;
 }
 
-int
-flash_check_blank (const uint8_t *p_start, size_t size)
+bool flash_check_blank (const uint8_t *p_start, size_t size)
 {
     const uint8_t *p;
 
     for (p = p_start; p < p_start + size; p++)
         if (*p != 0xff)
-            return 0;
+            return false;
 
-  return 1;
+    return true;
 }
diff --git a/sc_hsm.c b/sc_hsm.c
index 7c8cbf7..0609349 100644
--- a/sc_hsm.c
+++ b/sc_hsm.c
@@ -200,6 +200,42 @@ static int cmd_read_binary()
     return SW_OK();
 }
 
+int check_pin(const file_t *pin, const uint8_t *data, size_t len) {
+    if (!pin)
+        return SW_FILE_NOT_FOUND();
+    if (!pin->data) {
+        return SW_REFERENCE_NOT_FOUND();
+    }
+    if (len != pin->data[0])
+        return SW_CONDITIONS_NOT_SATISFIED();
+    if (memcmp(pin->data+2, data, len) != 0) {
+        if (pin_wrong_retry(pin) != HSM_OK)
+            return SW_PIN_BLOCKED();
+        return SW_SECURITY_STATUS_NOT_SATISFIED();
+    }
+    return reset_pin_retries(pin);
+}
+
+static int cmd_reset_retry() {
+    if (P1(apdu) == 0x0) {
+        if (P2(apdu) == 0x81) {
+            if (!file_sopin || !file_pin1) {
+                return SW_FILE_NOT_FOUND();
+            }
+            if (!file_sopin->data) {
+                return SW_REFERENCE_NOT_FOUND();
+            }
+            uint16_t r = check_pin(file_sopin, apdu.cmd_apdu_data, 8);
+            if (r != 0x9000)
+                return r;
+            flash_write_data_to_file(file_pin1, apdu.cmd_apdu_data+8, apdu.cmd_apdu_data_len-8);
+            if (reset_pin_retries(file_pin1) != HSM_OK)
+                return SW_MEMORY_FAILURE();
+            return SW_OK();
+        }
+    }
+}
+
 typedef struct cmd
 {
   uint8_t ins;
@@ -210,6 +246,7 @@ typedef struct cmd
 #define INS_READ_BINARY				0xB0
 #define INS_READ_BINARY_ODD         0xB1
 #define INS_VERIFY                  0x20
+#define INS_RESET_RETRY             0x2C
 
 static const cmd_t cmds[] = {
     { INS_SELECT_FILE, cmd_select },
@@ -217,6 +254,7 @@ static const cmd_t cmds[] = {
     { INS_READ_BINARY, cmd_read_binary },
     { INS_READ_BINARY_ODD, cmd_read_binary },
     { INS_VERIFY, cmd_verify },
+    { INS_RESET_RETRY, cmd_reset_retry },
     { 0x00, 0x0}
 };
 
diff --git a/sc_hsm.h b/sc_hsm.h
index f151e4b..4161564 100644
--- a/sc_hsm.h
+++ b/sc_hsm.h
@@ -9,6 +9,8 @@ extern const uint8_t sc_hsm_aid[];
 
 #define SW_BYTES_REMAINING_00()             set_res_sw (0x61, 0x00)
 #define SW_WARNING_STATE_UNCHANGED()        set_res_sw (0x62, 0x00)
+#define SW_PIN_BLOCKED()                    set_res_sw (0x63, 0x00)
+#define SW_MEMORY_FAILURE()                 set_res_sw (0x65, 0x81)
 #define SW_WRONG_LENGTH()                   set_res_sw (0x67, 0x00)
 #define SW_WRONG_DATA()                     set_res_sw (0x67, 0x00)
 #define SW_LOGICAL_CHANNEL_NOT_SUPPORTED()  set_res_sw (0x68, 0x81)
@@ -16,7 +18,7 @@ extern const uint8_t sc_hsm_aid[];
 #define SW_SECURITY_STATUS_NOT_SATISFIED()  set_res_sw (0x69, 0x82)
 #define SW_FILE_INVALID ()                  set_res_sw (0x69, 0x83)
 #define SW_DATA_INVALID ()                  set_res_sw (0x69, 0x84)
-#define SW_CONDITIONS_NOT_SATISFIED         set_res_sw (0x69, 0x85)
+#define SW_CONDITIONS_NOT_SATISFIED()       set_res_sw (0x69, 0x85)
 #define SW_COMMAND_NOT_ALLOWED()            set_res_sw (0x69, 0x86)
 #define SW_APPLET_SELECT_FAILED()           set_res_sw (0x69, 0x99)
 #define SW_FUNC_NOT_SUPPORTED()             set_res_sw (0x6A, 0x81)
@@ -30,6 +32,16 @@ extern const uint8_t sc_hsm_aid[];
 #define SW_INS_NOT_SUPPORTED()              set_res_sw (0x6D, 0x00)
 #define SW_CLA_NOT_SUPPORTED()              set_res_sw (0x6E, 0x00)
 #define SW_UNKNOWN()                        set_res_sw (0x6F, 0x00)
-#define SW_OK()			                    set_res_sw (0x90, 0x00)
+#define SW_OK()                             set_res_sw (0x90, 0x00)
+
+#define HSM_OK                              0
+#define HSM_ERR_NO_MEMORY                   -1000
+#define HSM_ERR_MEMORY_FATAL                -1001
+#define HSM_ERR_NULL_PARAM                  -1002
+#define HSM_ERR_FILE_NOT_FOUND              -1003
+#define HSM_ERR_BLOCKED                     -1004
+
+extern int reset_pin_retries(const file_t *pin);
+extern int pin_wrong_retry(const file_t *pin);
 
 #endif
\ No newline at end of file