Https SSL/TLS PreMaster/Master Secret (Key) computing

Https SSL/TLS PreMaster/Master Secret (Key) computing

Many people are confused about how the PreMaster/Master Secret (Key) is calculated when studying Https SSL/TLS. Recently, by looking at other materials and openssl source code, summarize the computing process of the PreMaster/Master Secret (Key:

 

Both Client Random and Server Random are explained in the previous "Https (SSL/TLS) Principle details". Both Client Hello and Server Hello send Random numbers to each other, it is used to calculate the Master Secret.

For the calculation of the PreMaster Secret (Key), it is mainly generated through RSA or Diffie-Hellman algorithm. We can see that in the Say Hello stage, random numbers are transmitted in plain text. If the PreMaster Secret is leaked, the entire SSL/TLS is invalid.

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