[TLS] CPU cost of 1RTT handshake

Watson Ladd <watsonbladd@gmail.com> Sun, 10 August 2014 20:35 UTC

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Date: Sun, 10 Aug 2014 13:35:13 -0700
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From: Watson Ladd <watsonbladd@gmail.com>
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Subject: [TLS] CPU cost of 1RTT handshake
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Dear all,

Right now, instead of the server defining the group to be used and
sending a key in the group, the client computes multiple keys, and the
server selects one. This is very bad for embedded devices with
constrained CPU, especially if they are connecting to a server over
high-latency, low-bandwidth links.

The justification for the current behavior is similarity to 0-RTT. But
I'm not convinced that this actually makes the protocol or
implementations any simpler, and it has real costs for many devices
that will otherwise not adopt TLS or try to invent their own encrypted
protocols.

Sincerely,
Watson Ladd