Confusion on directed advertising

[Darshan]

I want my device to pair only with a single central device at a time. So once it gets paired, it should not be able to pair with any other device. For this purpose I use directed advertising after pairing. But somehow, even directed advertising is being captured by apps like LigtBlue and other similar applications, and it allows to pair again. Am I on correct path to use directed advertising for pursuing my purpose to pair to a single device at a time?

I am using nrf51822 chip in peripheral mode.

[Ulrich Myhre]

Directed Advertisements are using an implicit whitelist for the single peer you are advertising to, so this should not be picked up by others. Are you sure that the code is not falling back to normal advertisement after some time?

[Darshan]

Yes checked code, and its falling to FAST advertising mode. Will fix it, and will let you know the result.

[run_ar]

Please note that you cannot rely on the whitelist or direct advertising feature alone. An attacker can use the same address as your known peer, thus passing this barrier quite easily. So in addition you should make sure you are not refreshing the bond if that happens.