I'm trying to do some manual data extraction/encryption/decryption with the
openssl command line tool.
I've been reviewing RFC5246 to work out what I need to do. It is not crystal clear to me if I am going to be able to do this step with that tool. I'm assuming the private key in the explanation is the private key generated when I created my self signed certificate.
When RSA is used for server authentication and key exchange, a 48- byte pre_master_secret is generated by the client, encrypted under the server's public key, and sent to the server. The server uses its private key to decrypt the pre_master_secret. Both parties then convert the pre_master_secret into the master_secret, as specified above.
Can someone tell me if my assumptions are correct. Can the
openssl command line tool be used and supplied with my server private key and encrypted pre_master_secret from the client to generate the pre_master key for the server so it can be used to create the master key?
If so, I am not sure how to do it as I'm not very familiar with the tool.
The other thing I should point out is that the cipher suite I am working with is TLS_RSA_WITH_AES_256_CBC_SHA and I can see in Wireshark that the pre_master_secret from the client is 256 bytes long.