Always check the TLS 1.3 downgrade signal.

These APIs were used by Chromium to control the carve-out for the TLS
1.3 downgrade signal. As of,
Chromium no longer uses them.

Update-Note: SSL_CTX_set_ignore_tls13_downgrade,
SSL_set_ignore_tls13_downgrade, and SSL_is_tls13_downgrade now do
nothing. Calls sites should be removed. (There are some copies of older
Chromium lying around, so I haven't removed the functions yet.) The
enforcement was already on by default, so this CL does not affect
callers that don't use those functions.

Change-Id: I016af8291cd92051472d239c4650602fe2a68f5b
Reviewed-by: Adam Langley <>
9 files changed
tree: fc1f223e9111ac8cad737f3902e999b940b484ad
  1. .clang-format
  2. .github/
  3. .gitignore
  7. CMakeLists.txt
  16. codereview.settings
  17. crypto/
  18. decrepit/
  19. fuzz/
  20. go.mod
  21. go.sum
  22. include/
  23. sources.cmake
  24. ssl/
  25. third_party/
  26. tool/
  27. 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.

Project links:

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