There are a few places where it is useful to run ECDSA with a specified
nonce:
- An ECDSA KAT in the module self-check
- Unit tests for particular test vectors
- Fuzzing the implementation (requested by the cryptofuzz project)
This replaces the fixed_k machinery with a separate function. Although
they are effectively the same, I've used two different functions.
One is internal and only used in the module self-check. The other is
exported for unit tests and cryptofuzz but marked with a for_testing.
(Chromium's presubmits flag uses of "for_testing" functions outside of
unit tests. The KAT version isn't in a test per se, so it's a separate
function.)
Bug: 391
Change-Id: I0f764d89bf0ac2081307e1079623d508fb0f2df7
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/45867
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
The extra computation in the "setup" half is a remnant of
ECDSA_sign_setup, which was designed to amortize the message-independent
portion of the signature. We don't care about this amortization, but we
do want some control over k for testing. Instead, have ecdsa_sign_impl
take k and do the rest.
In doing so, this lets us compute m and kinv slightly later, which means
fewer temporaries are needed.
Bug: 391
Change-Id: I398004a5388ce5b7e839db6c36edf8464643d16f
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/45866
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
David Benjamin
Adam Langley