nrf_dfu_set_peer_data returns 8 and does NOT start DFU bootloader

[Andrew Ong]

I am having trouble turning on bonds for DFU. 

First of all, before I describe this pain, can I choose to avoid this battle by just allowing unbonded devices to DFU? e.g. set NRF_DFU_BLE_BUTTONLESS_SUPPORTS_BONDS = 0, and NRF_DFU_BLE_REQUIRES_BONDS = 0 and  attr_md.wr_auth = 0;? 

This is what I run into when I try to turn on bonding for DFU. Error 8, which I assume is INVALID_STATE, and I don't know what that means. I deleted the bond from my iPhone several times and rebonded again. I enabled Indications on the  DFU service. Yet I still get this "error 8". Or sometimes, my application will actually reboot into DFU, but then my DFU app sits there and does nothing, implying the iPhone can't find the nRF Bootloader for some reason, or the bond data was not passed correctly.  What is wrong?

 

<info> app: DFU_OP_ENTER_BOOTLOADER
<info> app: Writing peer data to the bootloader
<info> app: ---------------system attribute table: 8--------------
<error> app: nrf_dfu_set_peer_data error: 8
<error> app: enter_bootloader error: 8
<error> app: on_ctrl_pt_write error. rsp_code = 4
<error> app: Request to enter bootloader mode failed asynchroneously.

SDK 14.0.0 

S132 

I set NRF_DFU_BLE_BUTTONLESS_SUPPORTS_BONDS 1 and NRF_DFU_BLE_REQUIRES_BONDS 1 and flashed my bootloader already. 

[Andrew Ong]

OMG IT WORKS

I was able to DFU my device twice with the "dfu_unbonded.c" file! 

• my iPhone bonded
• NRF_DFU_BLE_BUTTONLESS_SUPPORTS_BONDS = 0, and NRF_DFU_BLE_REQUIRES_BONDS = 0
• attr_md.wr_auth = 1 on the DFU characteristic;  

The DFU still requires bonding because my attr_md.wr_auth = 1;. So then what is the point of NRF_DFU_BLE_BUTTONLESS_SUPPORTS_BONDS = 1, and NRF_DFU_BLE_REQUIRES_BONDS = 1 and using the "dfu_bonded.c" file? 

[Sigurd]

Hi,

Andrew Ong said:

The DFU still requires bonding because my attr_md.wr_auth = 1;. So then what is the point of NRF_DFU_BLE_BUTTONLESS_SUPPORTS_BONDS = 1, and NRF_DFU_BLE_REQUIRES_BONDS = 1 and using the "dfu_bonded.c" file? 

 Please see this answer.

[Andrew Ong]

Are you implying that if NRF_DFU_BLE_REQUIRES_BONDS = 0, the application bond is NOT forwarded to the bootloader and an attacker could intercept the connection and DFU another payload? 

[Sigurd]

No, the init package with the new firmware would need to be signed with the private key, so even if an attacker connected to the device in DFU mode, he would need to know the private key to upload a new firmware image.

There is also some information about DFU with and without bonds here.

[Andrew Ong]

I still don't understand what the difference is between using configuration 1: 

• dfu_unbonded.c
• with bonds
• NRF_DFU_BLE_BUTTONLESS_SUPPORTS_BONDS = 0, and NRF_DFU_BLE_REQUIRES_BONDS = 0

and using configuration 2:

• dfu_bonded.c  
• with bonds
• NRF_DFU_BLE_BUTTONLESS_SUPPORTS_BONDS = 1, and NRF_DFU_BLE_REQUIRES_BONDS = 1

it sounds like the only difference is that in configuration 1, the attacker could intercept the connection and DFU another payload as long as the payload is signed with the private key, whereas in configuration 2, the attacker has no chance to intercept because the bond info is passed to the bootloader, is that right?