How can i change mode and level with nrf54l15

[Taron]

Hi,

I tried to change security level, but it's not changing.

When i set CONFIG_BT_SMP_SC_ONLY=y, it's working well with security level 4,

but i want to change mode1, level3.

how can i change it?

Tool : VS code

SDK : nRF Connect SDK v2.8.0

Board : AN54L15Q-DB(nRF54L15)

thanks for helping

[Hieu]

Hello Taron,

Could you please share why you want level 3?

Hieu

[Taron]

HI,

Bluetooth LE defines 4 security levels in security mode 1:

• Level 1: No security (open text, meaning no authentication and no encryption) 
• Level 2: Encryption with unauthenticated pairing
• Level 3: Authenticated pairing with encryption
• Level 4: Authenticated LE Secure Connections pairing with encryption

Because level4 is not support old version phone, so i need to set level3

Thanks  

[Hieu]

Hello Taron,

If the phone cannot support LE Secure Connections, the pairing process will end with Level 3 automatically.
Please run some tests and confirm for yourself.

[Taron]

You mean if the phone can't support LE Secure Connections,it will change level4 to level3 automatically?

[Hieu]

Technically, if the phone can't support LE Secure Connections, the security will never have reached level 4, it goes to level 3 directly.

For extensive details, please refer to Bluetooth Core Specification v6.0, Vol 3, Part H, Security Manager Specification.

[Emil Lenngren]

If you enforce "secure connections only" using CONFIG_BT_SMP_SC_ONLY, then pairing attempts will be aborted if the remote device only supports level 3 or less. That is the whole point of "secure connections only". Either you get pairing with the highest security, or no pairing at all.

What phone do you have that does not support LESC? LESC was released in 2014 so should be supported by all recent phones produced the last 10 years.

[Taron]

I tried to connect without LE Secure Connection, but i got error about connect. it's not to level 3 directly