Make copy_from_prebuf constant time.

(Imported from upstream's 708dc2f1291e104fe4eef810bb8ffc1fae5b19c1.)

Performance penalty varies from platform to platform, and even key
length. For rsa2048 sign it was observed to reach almost 10%.

This is part of the fix for CVE-2016-0702.

Change-Id: Ie0860bf3e531196f03102db1bc48eeaf30ab1d58
Reviewed-by: Adam Langley <>
1 file changed
tree: 4c582e4e66a444be78203c5f3e172555dc081595
  1. .clang-format
  2. .gitignore
  4. CMakeLists.txt
  11. codereview.settings
  12. crypto/
  13. decrepit/
  14. fuzz/
  15. include/
  16. ssl/
  17. tool/
  18. util/


BoringSSL is a fork of OpenSSL that is designed to meet Google's needs.

Although BoringSSL is an open source project, it is not intended for general use, as OpenSSL is. We don't recommend that third parties depend upon it. Doing so is likely to be frustrating because there are no guarantees of API or ABI stability.

Programs ship their own copies of BoringSSL when they use it and we update everything as needed when deciding to make API changes. This allows us to mostly avoid compromises in the name of compatibility. It works for us, but it may not work for you.

BoringSSL arose because Google used OpenSSL for many years in various ways and, over time, built up a large number of patches that were maintained while tracking upstream OpenSSL. As Google's product portfolio became more complex, more copies of OpenSSL sprung up and the effort involved in maintaining all these patches in multiple places was growing steadily.

Currently BoringSSL is the SSL library in Chrome/Chromium, Android (but it's not part of the NDK) and a number of other apps/programs.

There are other files in this directory which might be helpful: