RE: Resolving private resolvable addresses

RK — Tue, 23 Feb 2016 13:15:20 GMT

perfect - if I'd read the spec properly and realized it was AES-128 I might have gotten further with it myself. I can work with those, thanks very much.

RE: Resolving private resolvable addresses

Pål Håland — Tue, 23 Feb 2016 12:29:48 GMT

Hi RK

You can try to use some of the functions attached to match a resolvable random address if you already have the IRK. But you would have to iterate over multiple IRK's. The AAR is as you mentioned not accessible when the SD is enabled.

Here is some functions related to IRK.

void generate_address_checksum(uint8_t * p_random, uint8_t * p_checksum, uint8_t * p_irk_array)
{
  nrf_ecb_hal_data_t encryption_data = {0};
  uint32_t errcode;
  uint8_t i;

  /* Reverse the array as the ECB expect it in big endian format */
  for (i=0; i<sizeof(encryption_data.key); i++)
  {
    encryption_data.key[i] = p_irk_array[sizeof(encryption_data.key)-1-i];
    if (i < 3)
    {
      encryption_data.cleartext[15-i] = p_random[i];
    }
  }

  errcode = sd_ecb_block_encrypt(&encryption_data);
  if(errcode)
  {
    ASSERT(false);
  }
  
  for (i=0; i<3; i++)
  {
    p_checksum[i] = encryption_data.ciphertext[15-i];
  }
}

bool match_random_address(ble_gap_addr_t address, uint8_t * p_irk_array)
{
  ble_gap_addr_t tmp_addr;

  if (address.addr_type != BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_RESOLVABLE)
  {
    return false;
  }

  memcpy(&tmp_addr.addr[3], &address.addr[3], 3);

  generate_address_checksum(&tmp_addr.addr[3], &tmp_addr.addr[0], p_irk_array);
  return (memcmp(address.addr, tmp_addr.addr, sizeof(address.addr)) == 0);
}

Keep in mind that I have not validated the code with the latest softdevice.

BR Pål