Can I implement pairing with LESC enabled with OOB in nRF52805; SDK 17.1.0 v7.2.0 S112 ?

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I’m having nRF52805 on a custom board (for our own application) using SDK 17.1.0 v7.2.0 S112 ( IDE: Segger Embedded Studio). Given the amount of memory this chip has (192/24 KB) according to data sheet.

The SoftDevice occupies 100Kb of flash(0x00000-0x19000) with Bootloader for DFU and around 15KB of RAM(0x2000 0000 - 0x2000 3D00), Please correct me,if I'm wrong. I included all the files and library from ble_app_hrs example and now i am running out of flash memory and want to optimize so that i can use LESC with pairing and bonding. I am attaching picture below.

So,my queries is below:

1. Is it possible to implement pairing and bonding using LESC using OOB as there is memory constrains?
2. Which crypto Library will be best suited for fast and cheap memory.?
3. List of relevant files needed for crypto library so that I can use LESC with less memory consumption.
4. Can i use the flash memory reserved by SoftDevice for DFU (if i plan to skip DFU) for my Application, so that flash will be more for application code writing.
5. How to simulate OOB value without generated by nordic API? (Because in my application i will get OOB from Cloud but this feature is not available for now but i want to test with some fixed OOB value for now).
6. Kindly, suggest any tutorial, example or link that will be helpful for above points.
7. How to minimize memory consumption in writing application. 

any help will be appriciable. Thanks in advance.

[Simonr]

Hi

To use the least amount of RAM and flash memory, I would recommend using micro-ecc instead of Oberon to have the smallest available size, this should save you ~13kB of Flash at least. I don't have the exact number on what the LESC feature itself will set you back, but ~40-50 kB is a conservative estimate. As I already mentioned, I doubt you'll be able to fit LESC and what you state in your initial ticket in an nRF52810 though, and my recommendation would be to move up to an nRF52832.

Best regards,

Simon