The case where ec_group_get_mont_data is NULL is only for arbitrary groups
which we now require to be prime order. BN_mod_exp_mont is fine with a NULL
BN_MONT_CTX. It will just compute it. Saves a bit of special-casing.

Also don't mark p-2 as BN_FLG_CONSTTIME as the exponent is public anyway.

Change-Id: Ie868576d52fc9ae5f5c9f2a4039a729151bf84c7
Reviewed-on: https://boringssl-review.googlesource.com/8307
Reviewed-by: Adam Langley <agl@google.com>

Functions which lose object reuse and need auditing:
- d2i_ECParameters
- d2i_ECPrivateKey

This adds a handful of bytestring-based APIs to handle EC key
serialization. Deprecate all the old serialization APIs. Notes:

- An EC_KEY has additional state that controls its encoding, enc_flags
  and conv_form. conv_form is left alone, but enc_flags in the new API
  is an explicit parameter.

- d2i_ECPrivateKey interpreted its T** argument unlike nearly every
  other d2i function. This is an explicit EC_GROUP parameter in the new
  function.

- The new specified curve code is much stricter and should parse enough
  to uniquely identify the curve.

- I've not bothered with a new version of i2d_ECParameters. It just
  writes an OID. This may change later when decoupling from the giant
  OID table.

- Likewise, I've not bothered with new APIs for the public key since the
  EC_POINT APIs should suffice.

- Previously, d2i_ECPrivateKey would not call EC_KEY_check_key and it
  was possible for the imported public and private key to mismatch. It
  now calls it.

BUG=499653

Change-Id: I30b4dd2841ae76c56ab0e1808360b2628dee0615
Reviewed-on: https://boringssl-review.googlesource.com/6859
Reviewed-by: Adam Langley <agl@google.com>

Running make_errors.go every time a function is renamed is incredibly
tedious. Plus we keep getting them wrong.

Instead, sample __func__ (__FUNCTION__ in MSVC) in the OPENSSL_PUT_ERROR macro
and store it alongside file and line number. This doesn't change the format of
ERR_print_errors, however ERR_error_string_n now uses the placeholder
"OPENSSL_internal" rather than an actual function name since that only takes
the uint32_t packed error code as input.

This updates err scripts to not emit the function string table. The
OPENSSL_PUT_ERROR invocations, for now, still include the extra
parameter. That will be removed in a follow-up.

BUG=468039

Change-Id: Iaa2ef56991fb58892fa8a1283b3b8b995fbb308d
Reviewed-on: https://boringssl-review.googlesource.com/5275
Reviewed-by: Adam Langley <agl@google.com>

This change exposes the functions needed to support arbitrary elliptic
curve groups. The Java API[1] doesn't allow a provider to only provide
certain elliptic curve groups. So if BoringSSL is an ECC provider on
Android, we probably need to support arbitrary groups because someone
out there is going to be using it for Bitcoin I'm sure.

Perhaps in time we can remove this support, but not yet.

[1] https://docs.oracle.com/javase/7/docs/api/java/security/spec/ECParameterSpec.html

Change-Id: Ic1d76de96f913c9ca33c46b451cddc08c5b93d80
Reviewed-on: https://boringssl-review.googlesource.com/4740
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

This is taken from upstream, although it originally came from us. This
will only take effect on 64-bit systems (x86-64 and aarch64).

Before:

Did 1496 ECDH P-256 operations in 1038743us (1440.2 ops/sec)
Did 2783 ECDSA P-256 signing operations in 1081006us (2574.5 ops/sec)
Did 2400 ECDSA P-256 verify operations in 1059508us (2265.2 ops/sec)

After:

Did 4147 ECDH P-256 operations in 1061723us (3905.9 ops/sec)
Did 9372 ECDSA P-256 signing operations in 1040589us (9006.4 ops/sec)
Did 4114 ECDSA P-256 verify operations in 1063478us (3868.4 ops/sec)

Change-Id: I11fabb03239cc3a7c4a97325ed4e4c97421f91a9

This saves about 6-7k of error data.

Change-Id: Ic28593d4a1f5454f00fb2399d281c351ee57fb14
Reviewed-on: https://boringssl-review.googlesource.com/3385
Reviewed-by: Adam Langley <agl@google.com>

Previously, error strings were kept in arrays for each subdirectory and
err.c would iterate over them all and insert them at init time to a hash
table.

This means that, even if you have a shared library and lots of processes
using that, each process has ~30KB of private memory from building that
hash table.

This this change, all the error strings are built into a sorted list and
are thus static data. This means that processes can share the error
information and it actually saves binary space because of all the
pointer overhead in the old scheme. Also it saves the time taken
building the hash table at startup.

This removes support for externally-supplied error string data.

Change-Id: Ifca04f335c673a048e1a3e76ff2b69c7264635be