Double encryption

[bperrin2]

Hi,

we would like to add a level of encryption above BLE. So first establish a secure connection via BLE and then exchanging message to establish a session with a second level of security. 

In the other hand, the nrf52840 has a crypto cell to help us for encryption. Is it possible to use it twice at the same time?

Thanks in advance for your feedback.

Bernard

[bperrin2]

Thank you Emil for your answer. The second level of security will be D-TLS like with simple crypto suites. This is not yet fixed.

Concerning the risk to lose packets: Is BLE not lossless? The data link layer uses NESN (next expected sequence number) and SN (sequence number) in order to repeat transmission of a packet until it get received before sending the next one. Is it really necessary to use a Write With Response in order to ensure a lossless link at the application level? Could you tell me more about that?