Central 4.0 and peripheral 4.2

[ponlakshmi]

Hi I am using Nrf51 and Softdevice S130.I know that softdevice S130 supporting Ble 4.2.This will act as a peripheral.My mobile phone supporting only Bluetooth version 4.0.When making connection to these tow devices what will be security level.In this case can we use the ECDH for application level encryption.

[bjorn-spockeli]

No, both sides of the link must support LE Secure Connections, (i.e. support BLE v4.2) in order to use the ECDH (Elliptic Curve Diffe-Hellmann) key exchange in the Link Layer.

If you want to implement ECDH encryption at the Application Layer, then you can use the Secure Bootloader's Cryptography library in SDK v12.x to generate public keys and compute the shared secret key.

Best regards

Bjørn

[bjorn-spockeli]

Yes, that should be possible using the cryptography library from SDK v12.x.