This reduces the usage of real cryptography in --cfg=fuzzing,
specifically replacing the secret->public key derivation with a
simple copy and ECDH with XOR of the public and private parts
(plus a stream of 1s to make a test pass that expected non-0
output).
It leaves secret tweak addition/multiplication as-is.
It also changes the context creation to over-allocate and store
the context flags at the end of the context buffer, allowing us
to easily test context flags in each function.
While it would be nice to have something fancier (eg XOR-based),
its not immediately obvious how to accomplish this, and better to
fix the issues I have than spend too much time on it.
Fixes#271.
This partially reverts b811ec133a
cc-rs builds C dependencies with reduced visibility to avoid
exporting the C symbols all the way out to any rust-built shared
libraries however we override it with SECP256K1_API. We should
avoid doing this, allowing LTO/DCE to do its work.
We can now run unit tests with the fuzz feature on, and they'll pass,
which is some assurance that fuzzing with the feature on won't lead to
spurious failures due to the fuzz harness inadequately simulating message
signing.
It's super dangerous to use Cargo features for this, since they can be set
accidentally (or maliciously by any crate in a user's entire dep tree). Instead
we can just require users set `RUSTFLAGS` appropriately, which we can easily
do in our fuzzing scripts.
This feature was not useful for Cargo users, since Cargo does not give you
the kind of fine-grained control over C library linkage that you need. So
it was just unnecessarily confusing and would cause the build to break if
you enabled it accidentally, say, with --all-features.
Clippy emits a warning since we define a method that has the same name
as a standard trait. Implement the trait `AsRef` instead of using a
custom method.
This is configurable in upstream now.
Fixes#214.
So far, this just sets it to `4`. It's tempting to set it to `2` when `lowmemory` is enabled
but `lowmemory` is about RAM and not about binary size. This is better addressed by
a resolution of #193.
libsecp256k1 really only barely uses libc at all, and in practice,
things like memcpy/memcmp get optimized into something other than a
libc call. Thus, if we provide simple stub headers, things seem to
work with wasm-pack just fine.
Jonathan Underwood
Matt Corallo
Kirill Fomichev
Gregory Hill
Andrew Poelstra
Tobin Harding
Elichai Turkel
Tibo-lg
Kohei Taniguchi
Tim Ruffing