Add changelog entry
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/ChangeLog.d/constant_time_module.txt b/ChangeLog.d/constant_time_module.txt
new file mode 100644
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+++ b/ChangeLog.d/constant_time_module.txt
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+Changes
+ * The mbedcrypto library includes new a source code module constant_time.c,
+ containing various functions meant to resist timing side channel attacks.
+ This module does not have a separate configuration option, and functions
+ from this module will be included in the build as required. Currently
+ the interface of this module is private and may change at any time.