diff --git a/firmware/basic/xxtea.c b/firmware/basic/xxtea.c
index c768d85..9ae81f8 100644
--- a/firmware/basic/xxtea.c
+++ b/firmware/basic/xxtea.c
@@ -37,6 +37,21 @@ void htonlp(uint32_t *v, uint8_t n)
     }
 }
 
+void xxtea_cbcmac(uint32_t mac[4], uint32_t *data,
+                    uint32_t len, uint32_t const key[4])
+{
+    if( len & 0x03 )
+        return;
+    mac[0]=0;mac[1]=0;mac[2]=0;mac[3]=0;
+    for(int i=0; i<len;){
+        mac[0] ^= data[i++];
+        mac[1] ^= data[i++];
+        mac[2] ^= data[i++];
+        mac[3] ^= data[i++];
+        xxtea_encode_words(mac, 4, key);
+    }
+}
+
 #define DELTA 0x9e3779b9
 #define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (k[(p&3)^e] ^ z)))
 
diff --git a/firmware/basic/xxtea.h b/firmware/basic/xxtea.h
index e8b99c9..da93394 100644
--- a/firmware/basic/xxtea.h
+++ b/firmware/basic/xxtea.h
@@ -1,6 +1,8 @@
 #ifndef _XXTEA_H_
 #define _XXTEA_H_
 
+void xxtea_cbcmac(uint32_t mac[4], uint32_t *data,
+        uint32_t len, uint32_t const key[4]);
 void xxtea_encode_words(uint32_t *v, int n, uint32_t const k[4]);
 void xxtea_decode_words(uint32_t *v, int n, uint32_t const k[4]);
 
diff --git a/firmware/filesystem/execute.c b/firmware/filesystem/execute.c
index 3232f02..ee387b0 100644
--- a/firmware/filesystem/execute.c
+++ b/firmware/filesystem/execute.c
@@ -10,11 +10,16 @@
 #include "filesystem/ff.h"
 #include "filesystem/select.h"
 
+#include "basic/xxtea.h"
+
+const uint32_t signature_key[4] = {0,0,0,0};
+const uint32_t decode_key[4] = {0,0,0,0};
+
 extern void * sram_top;
 
 /**************************************************************************/
 
-void execute_file (const char * fname){
+void execute_file (const char * fname, uint8_t checksignature, uint8_t decode){
     FRESULT res;
     FIL file;
     UINT readbytes;
@@ -27,6 +32,7 @@ void execute_file (const char * fname){
     dst=(void (*)(void)) 0x10001800;
 
     res=f_open(&file, fname, FA_OPEN_EXISTING|FA_READ);
+
     //lcdPrint("open: ");
     //lcdPrintln(f_get_rc_string(res));
     //lcdRefresh();
@@ -42,6 +48,26 @@ void execute_file (const char * fname){
         return;
     };
 
+    if( decode || checksignature )
+        if( readbytes & 0x03 )
+            return;
+    
+    if( checksignature ){
+        uint32_t mac[4];
+        uint32_t *data = (uint32_t*)dst;
+        uint32_t len = readbytes/4;
+        xxtea_cbcmac(mac, (uint32_t*)dst, len-4, signature_key);
+        if( data[len-4] != mac[0] || data[len-3] != mac[1]
+            || data[len-2] != mac[2] || data[len-1] != mac[3] ){
+            return;
+        }
+    }
+
+    if( decode ){
+        uint32_t *data = (uint32_t*)dst;
+        uint32_t len = readbytes/4;
+        xxtea_decode_words(data, len, decode_key);
+    }
     //lcdPrintInt(readbytes);
     //lcdPrintln(" bytes");
     //lcdRefresh();
@@ -60,6 +86,6 @@ void executeSelect(char *ext){
     filename[2]=0;
 
     if( selectFile(filename+2,ext) == 0)
-        execute_file(filename);
+        execute_file(filename,0,0);
 };
 
diff --git a/firmware/filesystem/execute.h b/firmware/filesystem/execute.h
index 7242d6d..8c52cae 100644
--- a/firmware/filesystem/execute.h
+++ b/firmware/filesystem/execute.h
@@ -1,7 +1,7 @@
 #ifndef _EXECUTE_H_
 #define _EXECUTE_H_
 
-void execute_file (const char * fname);
+void execute_file (const char * fname, uint8_t checksignature, uint8_t decode);
 void executeSelect(char *ext);
 
 #endif
diff --git a/firmware/funk/openbeacon.c b/firmware/funk/openbeacon.c
index 835d89d..4c1810b 100644
--- a/firmware/funk/openbeacon.c
+++ b/firmware/funk/openbeacon.c
@@ -10,11 +10,22 @@ const uint32_t key[4] = { 0xB4595344,0xD3E119B6,0xA814D0EC,0xEFF5A24E };
 const uint8_t useencryption = 1;
 const uint8_t mac[5] = {1,2,3,2,1};
 
-uint32_t oid = 0;
-uint32_t seq = 0;
-uint8_t strength = 0;
+volatile uint32_t oid = 0;
+volatile uint32_t seq = 0;
+volatile uint8_t strength = 0;
 
-void openbeaconSave()
+void openbeaconShutdown(void)
+{    
+    openbeaconSave(seq);
+}
+
+void openbeaconSaveBlock(void)
+{
+
+    openbeaconSave(seq + OPENBEACON_SAVE + 1);
+}
+
+void openbeaconSave(uint32_t s)
 {
     FIL file;
     BYTE buf[4];
@@ -23,7 +34,7 @@ void openbeaconSave()
     if( f_open(&file, "beacon", FA_OPEN_ALWAYS|FA_WRITE) )
         return;
 
-    uint32touint8p(seq, buf);
+    uint32touint8p(s, buf);
 
     if( f_write(&file, buf, 4, &readbytes) )
         return; 
@@ -37,7 +48,7 @@ void openbeaconRead()
     BYTE buf[4];
     UINT readbytes;
 
-    if( f_open(&file, "beacon", FA_OPEN_EXISTING|FA_READ) )
+    if( f_open(&file, "beacon.cfg", FA_OPEN_EXISTING|FA_READ) )
         return;
 
     if( f_read(&file, buf, 4, &readbytes) )
@@ -53,6 +64,7 @@ void openbeaconSetup(uint32_t id)
     oid = id;
     strength = 0;
     openbeaconRead();
+    openbeaconSaveBlock();
 }
 
 uint8_t openbeaconSendPacket(uint32_t id, uint32_t seq,
@@ -80,11 +92,11 @@ uint8_t openbeaconSend(void)
     nrf_set_strength(strength);
     nrf_set_tx_mac(sizeof(mac), mac);
 
-    status = openbeaconSendPacket(oid, seq++, 0xFF, strength++);
+    status = openbeaconSendPacket(oid, seq, 0xFF, strength++);
     if( strength == 4 )
         strength = 0;
-    if( seq % OPENBEACON_SAVECOUNTER  == 0 )
-        openbeaconSave();
+    if( seq++ & OPENBEACON_SAVE == OPENBEACON_SAVE )
+        openbeaconSaveBlock();
     return status;
 }
 
diff --git a/firmware/funk/openbeacon.h b/firmware/funk/openbeacon.h
index 2d2a539..85d6469 100644
--- a/firmware/funk/openbeacon.h
+++ b/firmware/funk/openbeacon.h
@@ -5,8 +5,11 @@
 #include "funk/nrf24l01p.h"
 #include "basic/byteorder.h"
 
-#define OPENBEACON_SAVECOUNTER  (1024*8)
-void openbeaconSave();
+#define OPENBEACON_SAVE 0xFFFF
+
+void openbeaconShutdown(void);
+void openbeaconSaveBlock(void);
+void openbeaconSave(uint32_t s);
 void openbeaconRead();
 void openbeaconSetup(uint32_t id);
 uint8_t openbeaconSendPacket(uint32_t id, uint32_t ctr,