Don't use BN_nnmod to convert from field element to scalar.

Hasse's theorem implies at most one subtraction is necessary. This is
still using BIGNUM for now because field elements
(EC_POINT_get_affine_coordinates_GFp) are BIGNUMs.

This gives an additional 2% speedup for signing.

Did 16000 ECDSA P-224 signing operations in 1064799us (15026.3 ops/sec)
Did 19000 ECDSA P-256 signing operations in 1007839us (18852.2 ops/sec)
Did 1078 ECDSA P-384 signing operations in 1079413us (998.7 ops/sec)
Did 484 ECDSA P-521 signing operations in 1083616us (446.7 ops/sec)

Did 16000 ECDSA P-224 signing operations in 1054918us (15167.1 ops/sec)
Did 20000 ECDSA P-256 signing operations in 1037338us (19280.1 ops/sec)
Did 1045 ECDSA P-384 signing operations in 1049073us (996.1 ops/sec)
Did 484 ECDSA P-521 signing operations in 1085492us (445.9 ops/sec)

Change-Id: I2bfe214f968eca7a8e317928c0f3daf1a14bca90
Reviewed-by: Adam Langley <>
2 files changed
tree: 0a492ac9b939081d29e3bf157b7a81e95f01c824
  1. .clang-format
  2. .github/
  3. .gitignore
  6. CMakeLists.txt
  14. codereview.settings
  15. crypto/
  16. decrepit/
  17. fipstools/
  18. fuzz/
  19. include/
  20. infra/
  21. sources.cmake
  22. ssl/
  23. third_party/
  24. tool/
  25. 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: