NRF51822 Beacon with Secure Connection

[silex]

Hello, I have enough experience for ARM MCUs but I am newbie to BLE technology. I am thinking of a project about using NRF51822 beacon to unlock door when in range. I am using Keil v5 and PCA10028 devkit. I tried beacon example in SDK, which use indirect advertisement. It works, but not secure. Firstly, i want beacon and my gateway get paired first with 6digit password. After that, beacon must go to sleep mode , then wake up and send its ID for every 4seconds. Because battery life is important. I want your help on this. How can i do this? Which protocol should i use? Are there any example for such application?

Thank you so much.

[silex]

Thats correct. I am thinking of 2 ways; 1- After being powered up, central device want to connect to beacon (peripheral) with password. After they got paired, beacon sleeps for 4 seconds, then sends its UUID, RSSI etc, and then again sleep for 4 seconds again. In this way, a low level security can be established via 6 digit password. 2- AES encryption. Beacon sends the data using indirected advertisement, but this data must be AES encrypted. Central device knows AES passkey, and decrypts the data.

Are these possible, and how? Which one is quicker solution? Thanks