Nus client and write to secure characteristic

RE: Nus client and write to secure characteristic

Raghav Iyer — Thu, 21 Jun 2018 05:47:48 GMT

Hi Edvin,

I got it working. I had to call pm_conn_secure and wait for conn secure success event and then send it over the secure characteristic.

RE: Nus client and write to secure characteristic

Raghav Iyer — Wed, 20 Jun 2018 16:37:20 GMT

Hi,

I have modified the lesc example and added the nus service instead of the hrs.

I have established the bond between central and peripheral and made sure in the event BLE_GAP_EVT_AUTH_STATUS, lv4 is set to 1.

I connect to bonded peripheral, start discovery, once discovered I call assign handles on nus_c and then enable notification for txs characteristic and trying to send to rxs characteristic using ble_nus_c_string_send_secure function.

The function returns NRF_SUCCESS but the message is not received by the peripheral.

Is there anything else to be done?

RE: Nus client and write to secure characteristic

Edvin — Wed, 20 Jun 2018 13:58:47 GMT

Hello,

You need to handle the encryotion at one point.

since there are several levels on encryption (MITM is the highest one), it is not enough to bond.

Please see this example, which uses LESC:

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v13.0.0%2Fble_sdk_app_multirole_lesc.html

Best regards,

Edvin

RE: Nus client and write to secure characteristic

Raghav Iyer — Wed, 20 Jun 2018 12:19:49 GMT

I called the BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM in the nus_init function in the main.c

FYI, this is from nRF SDK 15.0.

I am not sure how I can encrypt the link, Since the peripheral works with nrf connect for android, I am assuming the app takes care of encrypting the link. I was assuming since I am using peer manager and I am connected to a lesc bonded peer, the encryption works automatically.

Can you give me sample of how to encrypt the link on the central device?

Thanks

RE: Nus client and write to secure characteristic

Edvin — Wed, 20 Jun 2018 12:07:05 GMT

Hello,

I wasn't able to compile with your ble_nus_c and ble_nus files, until I moved the BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM to inside the ble_nus.c file. Where did you place them?

Did you actually encrypt the link? Does any of the devices initiate encryption, and do you respond to it in the other device?

Best regards,

Edvin

RE: Nus client and write to secure characteristic

Raghav Iyer — Wed, 20 Jun 2018 06:58:03 GMT

devzone.nordicsemi.com/.../0513.ble_5F00_nus_5F00_c.c

RE: Nus client and write to secure characteristic

Raghav Iyer — Wed, 20 Jun 2018 06:57:27 GMT

devzone.nordicsemi.com/.../4314.ble_5F00_nus.c

RE: Nus client and write to secure characteristic

Raghav Iyer — Wed, 20 Jun 2018 06:56:20 GMT

devzone.nordicsemi.com/.../6403.ble_5F00_nus_5F00_c.h

devzone.nordicsemi.com/.../8880.ble_5F00_nus.h

RE: Nus client and write to secure characteristic

Raghav Iyer — Wed, 20 Jun 2018 06:55:04 GMT

Hi Edvin,

I will attach files that I have changed and this is how I have configured the NUS service on the peripheral

BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM(&nus_init.nus_rxs_attr_md.cccd_write_perm);
BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM(&nus_init.nus_rxs_attr_md.read_perm);
BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM(&nus_init.nus_rxs_attr_md.write_perm);

BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM(&nus_init.nus_txs_attr_md.cccd_write_perm);
BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM(&nus_init.nus_txs_attr_md.read_perm);
BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM(&nus_init.nus_txs_attr_md.write_perm);


Please check the function ble_nus_c_string_send_secure in the nus client

RE: Nus client and write to secure characteristic

Edvin — Wed, 20 Jun 2018 06:23:03 GMT

Hello,

So, what does your implementation look like? What is the difference between ble_nus_c_string_send and ble_nus_c_string_send_secure? Do they write to the same characteristic, or does it write to the new characteristics, rxs? Is the rxs set up properly on the peripheral?

It is a bit difficult to say what the issue may be only with a brief description of your implementation. Could you upload at least the implementation of ble_nus_c_string_send_secure()?

Best regards,

Edvin