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From "Andre Schild" <A.Sch...@aarboard.ch>
Subject Antw: RE: [users@httpd] SSL network performance impact?
Date Thu, 18 Dec 2003 09:22:29 GMT
>All this assumes that the increase in time to encrypt the data is more
>than the increase in data size due to encryption. My understanding of
>encryption is that it does not significantly swell the data payload so I
>think that this is a safe assumption.

There is a difference in data content who can cause a much slower transfer.

When you use a connection who does datacompression on the fly,
(like analogue V.90 modems etc., or routers with PPP compression on)
then normal HTML content can be compressed very much by
the partners. 

So a 5kB HTML page only has to transfer 2kB when it's not SSL
When the traffic is wrapped in HTTPS/SSL, then two things happen:

1. There is a small overhead for the key-exchange
2. There is a small additional headers/footers added to wrap the
    html content.
3. The data is enrypted.

Point 1 and 2 aren't the ones who give much additional traffic.
But the effect of point 3 is, that (almost) no compression can be done by
whatever intermediate parts.

Of course in most setups it's more a question of serverside CPU power 
for SSL enc/dec AND the very same applies to the client side !

André



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