diff --git a/tools/blupdater/CMakeLists.txt b/tools/blupdater/CMakeLists.txt
index 56f4c040f..990529f70 100644
--- a/tools/blupdater/CMakeLists.txt
+++ b/tools/blupdater/CMakeLists.txt
@@ -3,7 +3,8 @@ if(NOT ${KK_EMULATOR})
       main.c
       startup.s
       ../bootloader/bl_mpu.c
-      ../bootloader/isr.s)
+      ../bootloader/isr.s
+      header.s)
 
   include_directories(
       ${CMAKE_SOURCE_DIR}/include
diff --git a/tools/blupdater/blupdater.ld b/tools/blupdater/blupdater.ld
index 5dffb172b..c69522a0c 100644
--- a/tools/blupdater/blupdater.ld
+++ b/tools/blupdater/blupdater.ld
@@ -5,7 +5,7 @@
 MEMORY
 {
     /* blupdater ROM */
-    rom (rx)   : ORIGIN = 0x08060100, LENGTH = 0x00100000 - 0x00060100
+    rom (rx)   : ORIGIN = 0x08060000, LENGTH = 0x00100000 - 0x00060000
 
     /* ram shared by bootloader and firmware, contains msp (blupdater does not use psp) */
     ram (rwx) : ORIGIN = 0x20000000, LENGTH = 0x0001FF00
@@ -14,6 +14,12 @@ MEMORY
     comram (rwx) : ORIGIN = 0x2001FF00, LENGTH = 0x100
 }
 
+SECTIONS
+{
+    .header : ALIGN(4) {
+        KEEP(*(.header));
+    } >rom AT >rom
+}
 INCLUDE libopencm3_stm32f2.ld
 
 SECTIONS
@@ -35,7 +41,7 @@ _comram_end = ORIGIN(comram) + LENGTH(comram);
 /* potential bootloader/firmware isr vector changes. */
 
 /* this is the msp for the blupdater. Make stacks 8-byte aligned. */
-_stack = _ram_end - 24;                
+_stack = _ram_end - 24;
 __stack_chk_guard = _ram_end - 24;
 
 /* statics needed for the blupdater */
@@ -51,13 +57,10 @@ _mmhusr_isr = _comram_end - 24;
 _param_3 = _comram_end - 20;
 _param_2 = _comram_end - 16;
 _param_1 = _comram_end - 12;
-_timerusr_isr = _comram_end - 8; 
+_timerusr_isr = _comram_end - 8;
 _buttonusr_isr = _comram_end - 4;
 
 
 _data_size = SIZEOF(.data);
 
-
-
-
-
+_codelen = SIZEOF(.text) + SIZEOF(.data) + SIZEOF(.ARM.exidx) + SIZEOF(.version);
diff --git a/tools/blupdater/header.s b/tools/blupdater/header.s
new file mode 100644
index 000000000..431a706fa
--- /dev/null
+++ b/tools/blupdater/header.s
@@ -0,0 +1,18 @@
+    .syntax unified
+
+    .section .header, "a"
+
+    .type g_header, %object
+    .size g_header, .-g_header
+
+g_header:
+    .byte 'K','P','K','Y'
+    .word _codelen
+    .byte 0                // sigindex1
+    .byte 0                // sigindex2
+    .byte 0                // sigindex3
+    .byte 3                // flags: Preserve | UpdateAfter
+    . = . + 52             // reserved
+    . = . + 64             // sig1
+    . = . + 64             // sig2
+    . = . + 64             // sig3
diff --git a/tools/firmware/CMakeLists.txt b/tools/firmware/CMakeLists.txt
index 6dad2d07e..358afdb80 100644
--- a/tools/firmware/CMakeLists.txt
+++ b/tools/firmware/CMakeLists.txt
@@ -3,7 +3,8 @@ if(NOT ${KK_EMULATOR})
       keepkey_main.c
       startup.s
       ../bootloader/bl_mpu.c
-      ../bootloader/isr.s)
+      ../bootloader/isr.s
+      header.s)
 
   include_directories(
       ${CMAKE_SOURCE_DIR}/include
diff --git a/tools/firmware/header.s b/tools/firmware/header.s
new file mode 100644
index 000000000..dd5c476a9
--- /dev/null
+++ b/tools/firmware/header.s
@@ -0,0 +1,18 @@
+    .syntax unified
+
+    .section .header, "a"
+
+    .type g_header, %object
+    .size g_header, .-g_header
+
+g_header:
+    .byte 'K','P','K','Y'
+    .word _codelen
+    .byte 0                // sigindex1
+    .byte 0                // sigindex2
+    .byte 0                // sigindex3
+    .byte 1                // flags: Preserve
+    . = . + 52             // reserved
+    . = . + 64             // sig1
+    . = . + 64             // sig2
+    . = . + 64             // sig3
diff --git a/tools/firmware/keepkey.ld b/tools/firmware/keepkey.ld
index 24dd96582..f16424339 100644
--- a/tools/firmware/keepkey.ld
+++ b/tools/firmware/keepkey.ld
@@ -5,7 +5,7 @@
 MEMORY
 {
     /* Firmware ROM */
-    rom (rx)   : ORIGIN = 0x08060100, LENGTH = 0x00100000 - 0x00060100
+    rom (rx)   : ORIGIN = 0x08060000, LENGTH = 0x00100000 - 0x00060000
 
     /* ram shared by bootloader and firmware, contains psp */
     ram (rwx) : ORIGIN = 0x20000000, LENGTH = 0x1F800
@@ -24,6 +24,10 @@ SECTIONS
        *(confidential)
         ASSERT ((SIZEOF(.confidential) <= 32K), "Error: Confidential section too large");
     } >ram
+
+    .header : ALIGN(4) {
+        KEEP(*(.header));
+    } >rom AT >rom
 }
 
 INCLUDE libopencm3_stm32f2.ld
@@ -40,20 +44,19 @@ _ram_end = ORIGIN(ram) + LENGTH(ram);
 _bram_end = ORIGIN(bram) + LENGTH(bram);
 _comram_end = ORIGIN(comram) + LENGTH(comram);
 
-
 /* The following bootloader references can be removed after intermediate releases are completed */
 /* protected bootloader statics */
 _debug_1 = _bram_end - 16;
 _uisr = _bram_end - 12;
 button_sp_ctx = _bram_end - 8;
-timer_sp_ctx = _bram_end - 4; 
+timer_sp_ctx = _bram_end - 4;
 
 /* this is a reference to the msp*/
-_mspstack = _bram_end - 24;                
+_mspstack = _bram_end - 24;
 
 /* this is the psp. Make stacks 8-byte aligned. */
 _stack = _ram_end - 8;
-__stack_chk_guard = _ram_end - 8; 
+__stack_chk_guard = _ram_end - 8;
 
 /* common block vars to be accessed by both bootloader and firmware */
 
@@ -61,8 +64,10 @@ _mmhusr_isr = _comram_end - 24;
 _param_3 = _comram_end - 20;
 _param_2 = _comram_end - 16;
 _param_1 = _comram_end - 12;
-_timerusr_isr = _comram_end - 8; 
+_timerusr_isr = _comram_end - 8;
 _buttonusr_isr = _comram_end - 4;
 
 
 _data_size = SIZEOF(.data);
+
+_codelen = SIZEOF(.text) + SIZEOF(.data) + SIZEOF(.ARM.exidx) + SIZEOF(.version);