what is the meaning of difference of keys list distributed between own device and peer?

[JoonDong]

In ANCS example (SDK 11.0.0)

I thought keys list distributed should be the same naturally until I see the code below.

ret_code_t   dm_register( dm_application_instance_t    *p_appl_instance,
                          dm_application_param_t const   *p_appl_param )
{
    .
    .
    .

    m_application_table[0].sec_param.kdist_peer.enc  = 0;
    m_application_table[0].sec_param.kdist_peer.id   = 1;
    m_application_table[0].sec_param.kdist_peer.sign = 0;

    m_application_table[0].sec_param.kdist_own.enc   = 1;
    m_application_table[0].sec_param.kdist_own.id    = 1;
    m_application_table[0].sec_param.kdist_own.sign  = 0;
    
    .
    .
    .
}

Is there no problem, although keys distributed are different?

[Hung Bui]

Hi Joon,

No, there is no problem with that. This tells that the peripheral expect that it will be the one who distribute the encryption key (LTK) not the central. It's normal for LE legacy bonding that the peripheral generate the LTK.

[Hung Bui]

usually Iphone do distribute IRK as it uses Random resolvable address. Do you have a sniffer trace showing the otherwise ?

Absence of central's LTK meaning the central won't generate LTK , but the peripheral should do. And the link (on both direction) are encrypted with this LTK from the next time they connect (the initial connection, they use STK to encrypt instead).