Re: Issue: Sending ATT Signed Write Command via btgatt-client

[Szymon Janc <szymon.janc@tieto.com>]

Hi Ankur,

On Thursday 28 of May 2015 16:47:09 Ankur Patel wrote:
> Hello Folks,
> 
> I would like to Send Signed Write command to modify a characteristic on the
> Host. It failed into the Error: Failed to initiate write without response
> procedure
> 
> Information on Controller (May be helpful):
> root@imx28evk:~# cat /proc/crypto
> name         : ecb(aes)
> driver       : ecb-aes-dcp
> module       : kernel
> priority     : 400
> refcnt       : 1
> selftest     : passed
> type         : ablkcipher
> async        : yes
> blocksize    : 16
> min keysize  : 16
> max keysize  : 32
> ivsize       : 0
> geniv        : <default>
> 
> root@imx28evk:~# btmgmt info
> Index list with 1 item
> hci0:   Primary controller
>         addr 1C:BA:8C:86:81:21 version 6 manufacturer 13 class 0x000000
>         supported settings: powered connectable fast-connectable
> discoverable bondable link-security ssp br/edr hs le advertising debug-keys
> privacy current settings: powered connectable discoverable bondable
> link-security br/edr le advertising name testbt
>         short name
> 
> 
> root@imx28evk:~/tools# btgatt-client -d 00:1B:DC:07:2E:85
> Connecting to device... Done
> Service Added - UUID: 00001800-0000-1000-8000-00805f9b34fb start: 0x0001
> end: 0x000d Service Added - UUID: 00001801-0000-1000-8000-00805f9b34fb
> start: 0x0014 end: 0x0016 [GATT client]# GATT discovery procedures complete
> [GATT client]# ...
> [GATT client]# set-sign-key -c efcdab8967452301efcdab8967452301
> [GATT client]# write-value -s -w 0xd 01
> Failed to initiate write without response procedure
> 
> I tried to trace the error as:
> bt_gatt_client_write_without_response(..) -> bt_att_send(..) ->
> create_att_send_op(..) -> encode_pdu(..) -> bt_crypto_sign_att(..) -> As
> att->crypto is NULL it returns false.
> 
> I tried to check the reason for att->crypto to be NULL. Found that while
> initialization of the btgatt-client, under bt_crypto_new() ->
> crypto->ecb_aes = ecb_aes_setup();. It fails under ecb_aes_setup function.
> From the output of /proc/crypto, the kernel has the support. I am wondering
> how to enable the crypto?

Most likely following options are missing in your kernel configuration:
CONFIG_CRYPTO_CMAC
CONFIG_CRYPTO_USER_API
CONFIG_CRYPTO_USER_API_HASH
CONFIG_CRYPTO_USER_API_SKCIPHER

-- 
BR
Szymon Janc