attestation: Implemented a Sign operation.

Keys that were created with KEY_USAGE_SIGN usage can be used to sign
arbitrary data with the RSA-PKCS1v15-SHA256 mechanism.

BUG=brillo:737
TEST=unit, manual using 'attestation_client sign' and
'attestation_client verify'

Change-Id: Iafaf938e3df9bc65f82e5b134ccf94fa7f56b6b1
Reviewed-on: https://chromium-review.googlesource.com/270008
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Darren Krahn <dkrahn@chromium.org>
Tested-by: Darren Krahn <dkrahn@chromium.org>
24 files changed
tree: d7edb6baedd79e69a8ae3b2eaf5633ae6725b738
  1. OWNERS
  2. attestation.gyp
  3. attestation_testrunner.cc
  4. client/
  5. common/
  6. server/