Application goes to SVC Handler from sd_softdevice_enable in ble_stack_init when added NRF_CRYPTO_AES logic

[swetha Paladugu]

Hi,

I am using nrf52832 module, sdk 17.0.2.

I have ble nus service added and device works properly had no issues till i add the AES related files and defines.

Can you please help me how to resolve this issue?

[Hung Bui]

Hi Swetha, 
Could you let me know what exact issue you have when adding AES ? Do you have any log or screenshot when you get into the error ?
Where do you init AES ? Which crypto backend do you use ? 

[swetha Paladugu]

First of all... I would like to know if nrf52832 support aes cbc along with padding with ble communication.

[swetha Paladugu]

This is the code that i have in my main.c

/* Maximum allowed key = 256 bit */
static uint8_t m_key[16] = {'N', 'O', 'R', 'D', 'I', 'C', ' ',
'S', 'E', 'M', 'I', 'C', 'O', 'N', 'D', 'U', 'C', 'T', 'O', 'R',
'A', 'E', 'S', ' ', 'C', 'B', 'C', ' ', 'T', 'E', 'S', 'T'};

static char encrypted_text[NRF_CRYPTO_EXAMPLE_AES_MAX_TEXT_SIZE];
static char decrypted_text[NRF_CRYPTO_EXAMPLE_AES_MAX_TEXT_SIZE];

static void crypt_cbc(void)
{
uint8_t iv[16];
ret_code_t ret_val;
size_t len_in;
size_t len_out;

static nrf_crypto_aes_context_t cbc_encr_128_ctx; // AES CBC encryption context
static nrf_crypto_aes_context_t cbc_decr_128_ctx; // AES CBC decryption context

memset(encrypted_text, 0, sizeof(encrypted_text));
memset(decrypted_text, 0, sizeof(decrypted_text));

//
// Encryption phase
//

/* Init encryption context for 128 bit key and PKCS7 padding mode */
ret_val = nrf_crypto_aes_init(&cbc_encr_128_ctx,
&g_nrf_crypto_aes_cbc_128_pad_pkcs7_info,
NRF_CRYPTO_ENCRYPT);
AES_ERROR_CHECK(ret_val);

/* Set key for encryption context - only first 128 key bits will be used */
ret_val = nrf_crypto_aes_key_set(&cbc_encr_128_ctx, m_key);
AES_ERROR_CHECK(ret_val);

memset(iv, 0, sizeof(iv));
/* Set IV for encryption context */

ret_val = nrf_crypto_aes_iv_set(&cbc_encr_128_ctx, iv);
AES_ERROR_CHECK(ret_val);

len_in = strlen(m_plain_text);
len_out = sizeof(encrypted_text);

/* Encrypt text
When padding is selected m_encrypted_text buffer shall be at least 16 bytes larger
than text_len. */
ret_val = nrf_crypto_aes_finalize(&cbc_encr_128_ctx,
(uint8_t *)m_plain_text,
len_in,
(uint8_t *)encrypted_text,
&len_out);
AES_ERROR_CHECK(ret_val);

//
// Decryption phase
//

/* Init decryption context for 128 bit key and PKCS7 padding mode */
ret_val = nrf_crypto_aes_init(&cbc_decr_128_ctx,
&g_nrf_crypto_aes_cbc_128_pad_pkcs7_info,
NRF_CRYPTO_DECRYPT);
AES_ERROR_CHECK(ret_val);

/* Set key for decryption context - only first 128 key bits will be used */
ret_val = nrf_crypto_aes_key_set(&cbc_decr_128_ctx, m_key);
AES_ERROR_CHECK(ret_val);

memset(iv, 0, sizeof(iv));
/* Set IV for decryption context */

ret_val = nrf_crypto_aes_iv_set(&cbc_decr_128_ctx, iv);
AES_ERROR_CHECK(ret_val);

/* Decrypt text */
ret_val = nrf_crypto_aes_finalize(&cbc_decr_128_ctx,
(uint8_t *)encrypted_text,
len_out,
(uint8_t *)decrypted_text,
&len_out);
AES_ERROR_CHECK(ret_val);

/* trim padding */
decrypted_text[len_out] = '\0';

NRF_LOG_FLUSH();
if (memcmp(m_plain_text, decrypted_text, strlen(m_plain_text)) == 0)
{
NRF_LOG_RAW_INFO("AES CBC example with padding executed successfully.\r\n");
}
else
{
NRF_LOG_RAW_INFO("AES CBC example with padding failed!!!\r\n");
}
}

/**@brief Application main function.
*/
int main(void)
{
uint32_t err_code;

// Initialize the async SV CI interface to bootloader before any interrupts are enabled.
err_code = ble_dfu_buttonless_async_svci_init();

log_init();

err_code = nrf_crypto_init();
APP_ERROR_CHECK(err_code);

#if NRF_CRYPTO_BACKEND_MBEDTLS_ENABLED
err_code = nrf_mem_init();
APP_ERROR_CHECK(err_code);
#endif

timers_init();
power_management_init();
ble_stack_init();

gap_params_init();
gatt_init();
services_init();
advertising_init();
conn_params_init();

// Start execution.
advertising_start();

crypt_cbc();

while(1)
{
NRF_LOG_FLUSH();

idle_state_handle();
}
}

[swetha Paladugu]

[Hung Bui]

Hi Swetha, 

Please try to test this on a normal application, without the buttonless feature. I believe it's the reason you ended up in the SVC_handler. When you test buttonless application you need to flash the bootloader in addition. But we should test on normal BLE application first before testing with that. 

Also please try calling nrf_crypto_init() after you enabled the softdevice. 

Please check the log to find any error log. 

[swetha Paladugu]

4834.ble_app_uart.zip

Hi Hung,

As you suggested i tried to add aes in ble_app_uart example and i still find the same crash in SVC Handler..

I have uploaded the ble_app_uart example project where i have made changes.

Could you please flash the same on your end and check?

Thanks,

Swetha.

[Hung Bui]

Hi Swetha, 

If you go to project options and change from this: 

To this: 

(A line break was missing. )

It then worked fine. 

[swetha Paladugu]

Ohk so that is the reason 2 semi colons are there... I considered it as a mistake and removed one semicolon.

Thanks Hung for helping me resolve the issue.