encryption - SSL: Server key length and browser connection info. Base understanding -

I have to understand something.

I generate the key with the exca, which is the UI Openssl.

I created a CA, then generate a server certificate for https and use this CA to sign the generated certificate. Newly built seats are sub-sections of CA (as far as I can tell). I put it in the CN for the domain, generate a new private key of 4096bit , export the CRT and keypay with the private key, in this case nginx upload and configure.

I am now accessing the site on https. I'm looking at clicking on the connection information in Firefox:

Connection encrypted: High-level encryption (TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 128 bit )

In Chromium :

Your connection to domain.tld is encrypted with 128-bit encryption. & Lt; ...>

Question / S:

My private key is 4096 bits Why does it use 128 bit?

Which of the 128 bit is used in 4096 bits?

Why am I generating a 4090 bit key if its length is only 1/32

I should understand how this process works.

4096-bit RSA key and its associated certificate provides authentication during connection and key agreement establishment , Allowing the client to verify that they are actually connected to your server, nor a man-in-the-middle claiming your server.

However, the command of RSA algorithm magnitude is slower than the symmetric algorithms like AES, with the same security properties, as well as being limited in the amount of data that can be encrypted. Therefore, it is not used to transmit the actual data, and instead a symmetric algorithm is agreed between a session key customer and the server.

In this case, the session key short-term (ECDH) algorithm, which allows the client and the server to get a random, shared key, without ever having to transmit the key. This is this key that is 128 bit, and it is being used with symmetric AES encryption algorithm (GCM).