Valgrind's checking of uninitialised memory behaves very much like a
check for constant-time code: branches and memory indexes based on
uninitialised memory trigger warnings. Therefore, if we can tell
Valgrind that some secret is “uninitialised”, it'll give us a warning if
we do something non-constant-time with it.
This was the idea behind https://github.com/agl/ctgrind. But tricks like
that are no longer needed because Valgrind now comes with support for
marking regions of memory as defined or not. Therefore we can use that
API to check constant-time code.
This CL defines |CONSTTIME_SECRET| and |CONSTTIME_DECLASSIFY|, which are
no-ops unless the code is built with
|BORINGSSL_CONSTANT_TIME_VALIDATION| defined, which it isn't by default.
So this CL is a no-op itself so far. But it does show that a couple of
bits of constant-time time are, in fact, constant-time—seemingly even
when compiled with optimisations, which is nice.
The annotations in the RSA code are a) probably not marking all the
secrets as secret, and b) triggers warnings that are a little
interesting:
The anti-glitch check calls |BN_mod_exp_mont| which checks that the
input is less than the modulus. Of course, it is because the input is
the RSA plaintext that we just decrypted, but the plaintext is supposed
to be secret and so branching based on its contents isn't allows by
Valgrind. The answer isn't totally clear, but I've run out of time on
this for now.
Change-Id: I1608ed0b22d201e97595fafe46127159e02d5b1b
Reviewed-on: https://boringssl-review.googlesource.com/c/33504
Reviewed-by: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
The change seems to have stuck, so bring us closer to C/++11 static asserts.
(If we later find we need to support worse toolchains, we can always use
__LINE__ or __COUNTER__ to avoid duplicate typedef names and just punt on
embedding the message into the type name.)
Change-Id: I0e5bb1106405066f07740728e19ebe13cae3e0ee
Reviewed-on: https://boringssl-review.googlesource.com/c/33145
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
An EVP_AEAD_CTX used to be a small struct that contained a pointer to
an AEAD-specific context. That involved heap allocating the
AEAD-specific context, which was a problem for users who wanted to setup
and discard these objects quickly.
Instead this change makes EVP_AEAD_CTX large enough to contain the
AEAD-specific context inside itself. The dominant AEAD is AES-GCM, and
that's also the largest. So, in practice, this shouldn't waste too much
memory.
Change-Id: I795cb37afae9df1424f882adaf514a222e040c80
Reviewed-on: https://boringssl-review.googlesource.com/c/32506
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
Reviewed-by: David Benjamin <davidben@google.com>
We would set it to block_size rather than zero. This doesn't cause
problems (the code behaves correctly with either value), but it is a
tiny missed optimization.
Change-Id: Ic751352750cc7ef74aa25a6cc96da82007199941
Reviewed-on: https://boringssl-review.googlesource.com/24364
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
crypto/{asn1,x509,x509v3,pem} were skipped as they are still OpenSSL
style.
Change-Id: I3cd9a60e1cb483a981aca325041f3fbce294247c
Reviewed-on: https://boringssl-review.googlesource.com/19504
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
Similarly, add EVP_AEAD_CTX_tag_len which computes the exact tag length
for required by EVP_AEAD_CTX_seal_scatter.
Change-Id: I069b0ad16fab314fd42f6048a3c1dc45e8376f7f
Reviewed-on: https://boringssl-review.googlesource.com/18324
Reviewed-by: Adam Langley <agl@google.com>
These behave like EVP_AEAD_CTX_{seal,open} respectively, but receive
ciphertext and authentication tag as separate arguments, rather than one
contiguous out or in buffer.
Change-Id: Ia4f1b83424bc7067c55dd9e5a68f18061dab4d07
Reviewed-on: https://boringssl-review.googlesource.com/16924
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
