Slide 8, SSL Session Protocol: Slide 8, SSL Session Protocol

Slide 10, SSL connection protocol: Slide 10, SSL connection protocol

  1. Firstly, in Session Protocol, there is a {S}_B, what is the function of this {S}_B? Does't it help in proving Alice's identity? Is it okay to remove this one?

  2. Secondly, there is no Cert_B in SSL connection. Why is it okay to remove Cert_B in the protocol? Cause Cert_B helps in proving the identity of Bobo's identity, without Cert_B, how can Alice know she is really talking to Bob?

  3. Thirdly, why should we use SSL connection protocol considering we already have SSL session protocol?

2 Answers 2


For third query, Since ssl session establishment use lengthy cryptography keys, so its consume more resources. Once session established one should use lighter process. So using Connection and Session logic, https become better in performance.


Answering because there doesn't seem to be a full answer yet.

  1. {S}_B means that the random value S is encrypted with Bob's public key. So now only Bob is able to read what S is. This is important, because K is derived from S, so only Bob will be able to derive K, thus decrypting h(msgs || K) successfully and sending it back to Alice as proof.
  2. Slide 10 assumes that an SSL session already exists, so S is already known to Alice and Bob, meaning K is already known to Alice and Bob (and no one else!), so they can be confident that they're talking to the person they communicated with in Slide 8.
  3. Like @Vishesh said, public key operations are slow, so we're able to skip most of the slow parts because we can remember things from the previous exchange.

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