Unable to disable pairing in my peripheral app

RE: Unable to disable pairing in my peripheral app

Hung Bui — Wed, 09 Jul 2025 09:18:02 GMT

Hi Pablo,

I don't see a reason why the characteristic requires encryption.

Could you try to go through the lesson in devacademy?

At step 1 in this excercise: https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-5-bluetooth-le-security-fundamentals/topic/blefund-lesson-5-exercise-1/

Can you just test with the original sample (without changing BT_GATT_PERM_WRITE to BT_GATT_PERM_WRITE_ENCRYPT ), to see if you can access the characteristic without encryption ?

RE: Unable to disable pairing in my peripheral app

mul — Tue, 08 Jul 2025 11:02:50 GMT

Hi Hung Bui ,

Thanks for your response. I am defining the service and characteristics as follows which shouldn't require an encrypted link? (I believe):

#define CUSTOM_SERVICE_UUID 0x180A
#define CUSTOM_CHAR_UUID_READ  0x2A01
#define CUSTOM_CHAR_UUID_WRITE 0x2A02

/* GATT Callbacks */
static ssize_t read_callback(struct bt_conn *conn,
                             const struct bt_gatt_attr *attr,
                             void *buf, uint16_t len, uint16_t offset)
{
    const uint8_t *value = attr->user_data;
    LOG_INF("GATT Read: 0x%02X", *value);
    return bt_gatt_attr_read(conn, attr, buf, len, offset, value, sizeof(*value));
}

static ssize_t write_callback(struct bt_conn *conn,
                              const struct bt_gatt_attr *attr,
                              const void *buf, uint16_t len, uint16_t offset,
                              uint8_t flags)
{
    uint8_t *value = attr->user_data;

    if (offset + len > sizeof(*value)) {
        return BT_GATT_ERR(BT_ATT_ERR_INVALID_OFFSET);
    }

    memcpy(value + offset, buf, len);
    LOG_INF("GATT Write: 0x%02X", *value);

    // TODO - Process data - analyse frame etc. 

    return len;
}

/* GATT Service Definition */
BT_GATT_SERVICE_DEFINE(custom_svc,
    BT_GATT_PRIMARY_SERVICE(BT_UUID_DECLARE_16(CUSTOM_SERVICE_UUID)),
    BT_GATT_CHARACTERISTIC(BT_UUID_DECLARE_16(CUSTOM_CHAR_UUID_READ),
                           BT_GATT_CHRC_READ,
                           BT_GATT_PERM_READ,
                           read_callback, NULL, &read_value),
    BT_GATT_CHARACTERISTIC(BT_UUID_DECLARE_16(CUSTOM_CHAR_UUID_WRITE),
                           BT_GATT_CHRC_WRITE,
                           BT_GATT_PERM_WRITE,
                           NULL, write_callback, &write_value)
);

RE: Unable to disable pairing in my peripheral app

Hung Bui — Mon, 07 Jul 2025 14:53:11 GMT

Hi Paolo,
Most likely your TX characteristic requires the link to be encrypted to access it (write to it). You need to remove that. Please check how you declare the characteristic.
I would suggest to take a look at our dev academy course here: academy.nordicsemi.com/.../