#StackBounty: #tls #key-exchange #diffie-hellman #ecc #performance What are the performance differences (for client and server) between…

Bounty: 50

My question is about the client and server performance for (EC)DHE.
I am having difficulties in understanding this picture (which is based on numbers from Ivan Ristic’ book “Bulletproof SSL and TLS”).

Let’s start with the third row “RSA 2048, DHE 2048”. I can understand that client and server computation times differ because creating a signature is different from verifying it.

I understand that ECDHE is faster than DHE and therefore the numbers in the second row are smaller than the ones in the third row.

My questions are:

  1. The effort for DHE and ECDHE is identical for client and server, isn’t it?
  2. Why is the client’s computation time for “RSA 2048, ECDHE 256” smaller than the server’s while for “RSA 2048, DHE 2048” it is the other way around?

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