BLE MIDI, Password when pairing #652

jhsa · 2021-12-23T22:33:46Z

jhsa
Dec 23, 2021

Is there a way to ask for a password when pairing the BT to a device?
As a Musician I wouldn't like the BLE MIDI module to pair to any device in the audience. If the person who did something like that knows what he/she is doing, could ruin someone's gig/show, by sending unwanted MIDI messages to the stage.
Does it make sense?
I have searched the discussions but couldn't find anything about this.
Thank you.

João

tttapa · 2021-12-23T22:53:19Z

tttapa
Dec 23, 2021
Maintainer

Control Surface uses the standard ESP-IDF BLE API, so you can configure the BLE setup to your liking. You might want to start here:

Control-Surface/src/MIDI_Interfaces/BLEMIDI/ESP32/midi-init.c

Line 79 in e654266

// Authentication and security

See also: https://github.com/tttapa/Control-Surface/tree/master/src/MIDI_Interfaces/BLEMIDI/ESP32#readme

3 replies

jhsa Dec 23, 2021
Author

I do apologize, but I am quite a beginner :(
I am looking at the code you have linked, but I cannot see where I can set a password and enable the authentication..

Thanks

tttapa Dec 24, 2021
Maintainer

but I cannot see where I can set a password and enable the authentication..

Well the code for setting a password is not there yet of course, you'll have to add it yourself. Did you see the Espressif examples and documentation I linked to in the readme?

Specifically, see https://github.com/espressif/esp-idf/blob/3bd5ae6b78705b3e419d34b86faac6e886b9bdbb/examples/bluetooth/bluedroid/ble/gatt_security_server/main/example_ble_sec_gatts_demo.c#L558

jhsa Dec 25, 2021
Author

So, do I need to edit the "Espressif Boards" on the Arduino IDE?
Sorry if this is a stupid question. As I said I am a beginner and I don't quite understand it :(
Thanks

jhsa · 2021-12-25T17:13:37Z

jhsa
Dec 25, 2021
Author

So, I guess I have to edit the midi-init.c fileP?
And, like this?

#ifdef ESP32

/**
 * @file
 * 
 * Initialization of the Bluetooth stack and registration of the MIDI BLE
 * application.
 * 
 * @todo   Implement de-initialization, cleaning up everything we've configured.
 */

#include "events.h"
#include "midi-private.h"

#include <esp32-hal-bt.h>
#include <esp_bt_main.h>
#include <esp_gap_ble_api.h>
#include <esp_gatt_common_api.h>

#include <assert.h>

bool midi_init(void) {
    if (!btStarted() && !btStart())
        return false;

    esp_err_t ret;

    esp_bluedroid_status_t bt_state = esp_bluedroid_get_status();
    if (bt_state == ESP_BLUEDROID_STATUS_UNINITIALIZED) {
        ret = esp_bluedroid_init();
        if (ret != ESP_OK) {
            ESP_LOGE("MIDIBLE", "Init bluetooth failed: %s",
                     esp_err_to_name(ret));
            return false;
        }
    }

    if (bt_state != ESP_BLUEDROID_STATUS_ENABLED) {
        ret = esp_bluedroid_enable();
        if (ret != ESP_OK) {
            ESP_LOGE("MIDIBLE", "Enable bluetooth failed: %s",
                     esp_err_to_name(ret));
            return false;
        }
    }

    ret = esp_ble_gatt_set_local_mtu(ESP_GATT_MAX_MTU_SIZE);
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "set local  MTU failed: %s", esp_err_to_name(ret));
        return false;
    }

    const char *name = "Control Surface (BLE)";
    ret = esp_ble_gap_set_device_name(name);
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "set device name failed: %s", esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gap_register_callback(gap_event_handler);
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "gap register error: %s", esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gatts_register_callback(gatts_event_handler);
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "GATTS register error: %s", esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gatts_app_register(midi_get_app_id());
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "GATTS app register error: %s",
                 esp_err_to_name(ret));
        return false;
    }

    // Authentication and security

    /* set the security iocap & auth_req & key size & init key response key parameters to the stack*/
    esp_ble_auth_req_t auth_req = ESP_LE_AUTH_REQ_SC_MITM_BOND;     //bonding with peer device after authentication
    esp_ble_io_cap_t iocap = ESP_IO_CAP_NONE;           //set the IO capability to No output No input
    uint8_t key_size = 16;      //the key size should be 7~16 bytes
    uint8_t init_key = ESP_BLE_ENC_KEY_MASK | ESP_BLE_ID_KEY_MASK;
    uint8_t rsp_key = ESP_BLE_ENC_KEY_MASK | ESP_BLE_ID_KEY_MASK;
    //set static passkey
    uint32_t passkey = 123456;
    uint8_t auth_option = ESP_BLE_ONLY_ACCEPT_SPECIFIED_AUTH_DISABLE;
    uint8_t oob_support = ESP_BLE_OOB_DISABLE;
    esp_ble_gap_set_security_param(ESP_BLE_SM_SET_STATIC_PASSKEY, &passkey, sizeof(uint32_t));
    esp_ble_gap_set_security_param(ESP_BLE_SM_AUTHEN_REQ_MODE, &auth_req, sizeof(uint8_t));
    esp_ble_gap_set_security_param(ESP_BLE_SM_IOCAP_MODE, &iocap, sizeof(uint8_t));
    esp_ble_gap_set_security_param(ESP_BLE_SM_MAX_KEY_SIZE, &key_size, sizeof(uint8_t));
    esp_ble_gap_set_security_param(ESP_BLE_SM_ONLY_ACCEPT_SPECIFIED_SEC_AUTH, &auth_option, sizeof(uint8_t));
    esp_ble_gap_set_security_param(ESP_BLE_SM_OOB_SUPPORT, &oob_support, sizeof(uint8_t));
    /* If your BLE device acts as a Slave, the init_key means you hope which types of key of the master should distribute to you,
    and the response key means which key you can distribute to the master;
    If your BLE device acts as a master, the response key means you hope which types of key of the slave should distribute to you,
    and the init key means which key you can distribute to the slave. */
    esp_ble_gap_set_security_param(ESP_BLE_SM_SET_INIT_KEY, &init_key, sizeof(uint8_t));
    esp_ble_gap_set_security_param(ESP_BLE_SM_SET_RSP_KEY, &rsp_key, sizeof(uint8_t));

    ret = esp_ble_gap_set_security_param(ESP_BLE_SM_AUTHEN_REQ_MODE, &auth_req,
                                         sizeof(auth_req));
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "Failed to set ESP_BLE_SM_AUTHEN_REQ_MODE: %s",
                 esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gap_set_security_param(ESP_BLE_SM_IOCAP_MODE, &iocap,
                                         sizeof(iocap));
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "Failed to set ESP_BLE_SM_IOCAP_MODE: %s",
                 esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gap_set_security_param(
        ESP_BLE_SM_ONLY_ACCEPT_SPECIFIED_SEC_AUTH, &auth_option,
        sizeof(auth_option));
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE",
                 "Failed to set ESP_BLE_SM_ONLY_ACCEPT_SPECIFIED_SEC_AUTH: %s",
                 esp_err_to_name(ret));
        return false;
    }

    vTaskDelay(100 / portTICK_PERIOD_MS);

    return true;
}

bool midi_deinit(void) { assert(!"Not implemented"); }

#endif

0 replies

jhsa · 2021-12-25T17:25:16Z

jhsa
Dec 25, 2021
Author

Hmm, obviously it does not work because ESP32 still pairs without asking for the passkey. I really need help with this as I have no idea of what I am doing. The only thing I know is that I might be editing the right file :(

0 replies

jhsa · 2021-12-25T18:05:35Z

jhsa
Dec 25, 2021
Author

Tried also this, but it also doesn't work. The BT pairs without asking for a key, and after that it works normally. I have no idea what else I can do. Thanks for your help.

#ifdef ESP32

/**
 * @file
 * 
 * Initialization of the Bluetooth stack and registration of the MIDI BLE
 * application.
 * 
 * @todo   Implement de-initialization, cleaning up everything we've configured.
 */

#include "events.h"
#include "midi-private.h"

#include <esp32-hal-bt.h>
#include <esp_bt_main.h>
#include <esp_gap_ble_api.h>
#include <esp_gatt_common_api.h>

#include <assert.h>

bool midi_init(void) {
    if (!btStarted() && !btStart())
        return false;

    esp_err_t ret;

    esp_bluedroid_status_t bt_state = esp_bluedroid_get_status();
    if (bt_state == ESP_BLUEDROID_STATUS_UNINITIALIZED) {
        ret = esp_bluedroid_init();
        if (ret != ESP_OK) {
            ESP_LOGE("MIDIBLE", "Init bluetooth failed: %s",
                     esp_err_to_name(ret));
            return false;
        }
    }

    if (bt_state != ESP_BLUEDROID_STATUS_ENABLED) {
        ret = esp_bluedroid_enable();
        if (ret != ESP_OK) {
            ESP_LOGE("MIDIBLE", "Enable bluetooth failed: %s",
                     esp_err_to_name(ret));
            return false;
        }
    }

    ret = esp_ble_gatt_set_local_mtu(ESP_GATT_MAX_MTU_SIZE);
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "set local  MTU failed: %s", esp_err_to_name(ret));
        return false;
    }

    const char *name = "Control Surface (BLE)";
    ret = esp_ble_gap_set_device_name(name);
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "set device name failed: %s", esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gap_register_callback(gap_event_handler);
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "gap register error: %s", esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gatts_register_callback(gatts_event_handler);
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "GATTS register error: %s", esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gatts_app_register(midi_get_app_id());
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "GATTS app register error: %s",
                 esp_err_to_name(ret));
        return false;
    }

    // Authentication and security

    /* set the security iocap & auth_req & key size & init key response key parameters to the stack*/
    esp_ble_auth_req_t auth_req = ESP_LE_AUTH_REQ_SC_MITM_BOND;     //bonding with peer device after authentication
    esp_ble_io_cap_t iocap = ESP_IO_CAP_NONE;           //set the IO capability to No output No input
    uint8_t key_size = 16;      //the key size should be 7~16 bytes
    uint8_t init_key = ESP_BLE_ENC_KEY_MASK | ESP_BLE_ID_KEY_MASK;
    uint8_t rsp_key = ESP_BLE_ENC_KEY_MASK | ESP_BLE_ID_KEY_MASK;
    //set static passkey
    uint32_t passkey = 123456;
    uint8_t auth_option = ESP_BLE_ONLY_ACCEPT_SPECIFIED_AUTH_DISABLE;
    
	ret = esp_ble_gap_set_security_param(ESP_BLE_SM_SET_STATIC_PASSKEY, &passkey, sizeof(passkey));
	
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "Failed to set ESP_BLE_SM_AUTHEN_REQ_MODE: %s",
                 esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gap_set_security_param(ESP_BLE_SM_IOCAP_MODE, &iocap,
                                         sizeof(iocap));
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE", "Failed to set ESP_BLE_SM_IOCAP_MODE: %s",
                 esp_err_to_name(ret));
        return false;
    }

    ret = esp_ble_gap_set_security_param(
        ESP_BLE_SM_ONLY_ACCEPT_SPECIFIED_SEC_AUTH, &auth_option,
        sizeof(auth_option));
    if (ret != ESP_OK) {
        ESP_LOGE("MIDIBLE",
                 "Failed to set ESP_BLE_SM_ONLY_ACCEPT_SPECIFIED_SEC_AUTH: %s",
                 esp_err_to_name(ret));
        return false;
    }

    vTaskDelay(100 / portTICK_PERIOD_MS);

    return true;
}

bool midi_deinit(void) { assert(!"Not implemented"); }

#endif

1 reply

tttapa Dec 27, 2021
Maintainer

I've tried something similar, and on my Android phone it does ask for a passkey, but on my Ubuntu laptop, it pairs without requiring a passkey. I don't know if that's because it was paired earlier, but clearing the ESP's list of bonded devices or even the entire flash doesn't seem to change anything.

Either way, this is probably a question for an ESP32-specific online forum (or GitHub issue section).

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BLE MIDI, Password when pairing #652

jhsa Dec 23, 2021

Replies: 4 comments · 4 replies

tttapa Dec 23, 2021 Maintainer

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tttapa Dec 27, 2021 Maintainer

jhsa
Dec 23, 2021

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