Hi,
folks wanted to use secure boot loader on nrf51 on the mynewt slack channel.
I thought I’d show an example about how to make this happen.
Add keys to use:
diff --git a/boot/bootutil/pkg.yml b/boot/bootutil/pkg.yml
index 20a7a58e..7abef9e7 100644
--- a/boot/bootutil/pkg.yml
+++ b/boot/bootutil/pkg.yml
@@ -31,6 +31,7 @@ pkg.deps:
- kernel/os
- sys/defs
- sys/flash_map
+ - mypkgs/ecc256_key
pkg.deps.BOOTUTIL_SIGN_EC256:
- crypto/tinycrypt
Create target:
[marko@IsMyLaptop:~/src/incubator-mynewt-blinky]$ newt target show
boot_bbc_crypto
targets/boot_bbc_crypto
app=@apache-mynewt-core/apps/boot
bsp=@apache-mynewt-core/hw/bsp/bbc_microbit
build_profile=optimized
syscfg=BOOTUTIL_SIGN_EC256=1
Make sure it fits in space allocated for secure bootloader:
ls -al bin/targets/boot_bbc_crypto/app/apps/boot/boot.elf.bin
-rwxr-xr-x 1 marko staff 13756 Jun 20 11:01
bin/targets/boot_bbc_crypto/app/apps/boot/boot.elf.bin
And the compare size against FLASH_AREA_BOOTLOADER in
repos/apache-mynewt-core/hw/bsp/bbc_microbit/bsp.yml (16kB max, so looks ok).
Verify image signature on every boot (as opposed to only when
swapping images).
First pull in change to fix this:
cd repos/apache-mynewt-core
git remote add marko g...@github.com:mkiiskila/incubator-mynewt-core.git
git pull marko boot_check_slot0-fix
Add cflag to target to do that:
newt target set boot_bbc_crypto cflags=-DBOOTUTIL_VALIDATE_SLOT0
[marko@IsMyLaptop:~/src/incubator-mynewt-blinky]$ newt target show
boot_bbc_crypto
targets/boot_bbc_crypto
app=@apache-mynewt-core/apps/boot
bsp=@apache-mynewt-core/hw/bsp/bbc_microbit
build_profile=optimized
cflags=-DBOOTUTIL_VALIDATE_SLOT0
syscfg=BOOTUTIL_SIGN_EC256=1
Make sure it does not boot:
newt run boot_bbc_crypto
(gdb) b boot.c:54
Breakpoint 1 at 0x2d0: file repos/apache-mynewt-core/apps/boot/src/boot.c, line
54.
(gdb) c
Continuing.
Note: automatically using hardware breakpoints for read-only addresses.
Breakpoint 1, main () at repos/apache-mynewt-core/apps/boot/src/boot.c:54
54 rc = boot_go(&rsp);
(gdb) n
55 assert(rc == 0);
(gdb) p rc
$1 = 3
Yup, does not boot.
Create a target that fits:
diff --git a/apps/bleprph_oic/pkg.yml b/apps/bleprph_oic/pkg.yml
index 34cdd45c..c01970b4 100644
--- a/apps/bleprph_oic/pkg.yml
+++ b/apps/bleprph_oic/pkg.yml
@@ -30,10 +30,9 @@ pkg.deps:
- net/nimble/host/services/gatt
- net/nimble/host/store/ram
- net/nimble/transport/ram
- - sys/console/full
- - sys/log/full
- - sys/stats/full
+ - sys/console/stub
+ - sys/log/stub
+ - sys/stats/stub
- mgmt/oicmgr
- sys/sysinit
- - sys/shell
- sys/id
[marko@IsMyLaptop:~/src/incubator-mynewt-blinky]$ newt target show
bleprph_oic_bbc
targets/bleprph_oic_bbc
app=@apache-mynewt-core/apps/bleprph_oic
bsp=@apache-mynewt-core/hw/bsp/bbc_microbit
build_profile=optimized
syscfg=BLE_ATT_SVR_MAX_PREP_ENTRIES=8:BLE_GATT_WRITE_MAX_ATTRS=6:BLE_HCI_EVT_HI_BUF_COUNT=4:BLE_HCI_EVT_LO_BUF_COUNT=3:BLE_LL_CONN_INIT_MAX_TX_BYTES=251:BLE_LL_MAX_PKT_SIZE=251:BLE_SM_LEGACY=0:LOG_FCB=0:LOG_LEVEL=0:LOG_NEWTMGR=0:LOG_SOFT_RESET=0:MSYS_1_BLOCK_COUNT=18:MSYS_1_BLOCK_SIZE=128:OC_LOGGING=0:OC_SEPARATE_RESPONSES=0:OC_TRANSPORT_SERIAL=0:OS_MAIN_STACK_SIZE=512
Build it:
[marko@IsMyLaptop:~/src/incubator-mynewt-blinky]$ newt build bleprph_oic_bbc
Building target targets/bleprph_oic_bbc
Target successfully built: targets/bleprph_oic_bbc
[marko@IsMyLaptop:~/src/incubator-mynewt-blinky]$ newt create-image
bleprph_oic_bbc 0.0.1
repos/apache-mynewt-core/mypkgs/ecc256_key/image_sign_prime256v1.pem
App image succesfully generated:
/Users/marko/src/incubator-mynewt-blinky/bin/targets/bleprph_oic_bbc/app/apps/bleprph_oic/bleprph_oic.img
Make sure that image signature is present:
[marko@IsMyLaptop:~/src/incubator-mynewt-blinky]$ od -t x1 -j 16 -N 4
bin/targets/bleprph_oic_bbc/app/apps/bleprph_oic/bleprph_oic.img
0000020 22 00 00 00
^
|
signature present
Load it:
[marko@IsMyLaptop:~/src/incubator-mynewt-blinky]$ newt load bleprph_oic_bbc
Loading app image into slot 1
Verify that bootloader passes checks:
[marko@IsMyLaptop:~/src/incubator-mynewt-blinky]$ newt debug boot_bbc_crypto
(gdb) b boot.c:55
Breakpoint 1 at 0x2d6: file repos/apache-mynewt-core/apps/boot/src/boot.c, line
55.
(gdb) c
Continuing.
Note: automatically using hardware breakpoints for read-only addresses.
Breakpoint 1, main () at repos/apache-mynewt-core/apps/boot/src/boot.c:55
55 assert(rc == 0);
(gdb) p rc
$1 = 0
-> Works
Hope this helps,
M
