mbedtls/ChangeLog.d/default-curves.txt
Gilles Peskine b1940a76ad In TLS, order curves by resource usage, not size
TLS used to prefer larger curves, under the idea that a larger curve has a
higher security strength and is therefore harder to attack. However, brute
force attacks are not a practical concern, so this was not particularly
meaningful. If a curve is considered secure enough to be allowed, then we
might as well use it.

So order curves by resource usage. The exact definition of what this means
is purposefully left open. It may include criteria such as performance and
memory usage. Risk of side channels could be a factor as well, although it
didn't affect the current choice.

The current list happens to exactly correspond to the numbers reported by
one run of the benchmark program for "full handshake/s" on my machine.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2021-06-17 21:46:29 +02:00

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Default behavior changes
* Some default policies for X.509 certificate verification and TLS have
changed: curves and hashes weaker than 255 bits are no longer accepted
by default. The default order in TLS now favors faster curves over larger
curves.
Removals
* Remove the compile-time option
MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE.