diff --git a/src/fido/cmd_authenticate.c b/src/fido/cmd_authenticate.c
index a03c830..4b48842 100644
--- a/src/fido/cmd_authenticate.c
+++ b/src/fido/cmd_authenticate.c
@@ -62,9 +62,13 @@ int cmd_authenticate() {
             return SW_WRONG_DATA();
         return SW_CONDITIONS_NOT_SATISFIED();
     }
-    resp->flags = 0x1;
-    resp->ctr[0] = 0;
-    uint8_t hash[32], sig_base[U2F_APPID_SIZE+1+4+U2F_CHAL_SIZE];
+    resp->flags = P1(apdu) == 0x03 ? 0x1 : 0x0;
+    uint32_t ctr = *(uint32_t *)file_get_data(ef_counter);
+    resp->ctr[0] = ctr >> 24;
+    resp->ctr[1] = ctr >> 16;
+    resp->ctr[2] = ctr >> 8;
+    resp->ctr[3] = ctr & 0xff;
+    uint8_t hash[32], sig_base[U2F_APPID_SIZE + 1 + 4 + U2F_CHAL_SIZE];
     memcpy(sig_base, req->appId, U2F_APPID_SIZE);
     memcpy(sig_base+U2F_APPID_SIZE, &resp->flags, sizeof(uint8_t));
     memcpy(sig_base + U2F_APPID_SIZE + 1, resp->ctr, 4);
@@ -80,5 +84,9 @@ int cmd_authenticate() {
     if (ret != 0)
         return SW_EXEC_ERROR();
     res_APDU_size = 1 + 4 + olen;
+
+    ctr++;
+    flash_write_data_to_file(ef_counter, (uint8_t *)&ctr, sizeof(ctr));
+    low_flash_available();
     return SW_OK();
 }
diff --git a/src/fido/fido.c b/src/fido/fido.c
index c5498aa..433e4ee 100644
--- a/src/fido/fido.c
+++ b/src/fido/fido.c
@@ -183,6 +183,16 @@ int scan_files() {
     else {
         printf("FATAL ERROR: CERT DEV not found in memory!\r\n");
     }
+    ef_counter = search_by_fid(EF_COUNTER, NULL, SPECIFY_EF);
+    if (ef_counter) {
+        if (file_get_size(ef_counter) == 0 || !ef_counter->data) {
+            uint32_t v = 0;
+            flash_write_data_to_file(ef_counter, (uint8_t *)&v, sizeof(v));
+        }
+    }
+    else {
+        printf("FATAL ERROR: Global counter not found in memory!\r\n");
+    }
     low_flash_available();
     return CCID_OK;
 }
diff --git a/src/fido/files.c b/src/fido/files.c
index 8072c83..4c031c8 100644
--- a/src/fido/files.c
+++ b/src/fido/files.c
@@ -22,6 +22,7 @@ file_t file_entries[] = {
     {.fid = 0x3f00, .parent = 0xff, .name = NULL, .type = FILE_TYPE_DF, .data = NULL, .ef_structure = 0, .acl = {0}},                                                                     // MF
     {.fid = EF_KEY_DEV, .parent = 0, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH | FILE_PERSISTENT, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = {0xff}},  // Device Key
     {.fid = EF_EE_DEV,  .parent = 0, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH | FILE_PERSISTENT, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = {0xff}},   // End Entity Certificate Device
+    {.fid = EF_COUNTER,  .parent = 0, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = {0xff}},   // Global counter
     { .fid = 0x0000, .parent = 0xff, .name = NULL, .type = FILE_TYPE_UNKNOWN, .data = NULL, .ef_structure = 0, .acl = {0} } //end
 };
 
@@ -29,3 +30,4 @@ const file_t *MF = &file_entries[0];
 const file_t *file_last = &file_entries[sizeof(file_entries)/sizeof(file_t)-1];
 file_t *ef_keydev = NULL;
 file_t *ef_certdev = NULL;
+file_t *ef_counter = NULL;
diff --git a/src/fido/files.h b/src/fido/files.h
index d59904a..950cec7 100644
--- a/src/fido/files.h
+++ b/src/fido/files.h
@@ -22,8 +22,10 @@
 
 #define EF_KEY_DEV      0xCC00
 #define EF_EE_DEV       0xCE00
+#define EF_COUNTER      0xC000
 
 extern file_t *ef_keydev;
 extern file_t *ef_certdev;
+extern file_t *ef_counter;
 
 #endif //_FILES_H_