Rather than have global initialization functions, which required
expensive synchronization on the part of the Rust library,
libsecp256k1 now carries its context in thread-local data which
must be passed to every function.
What this means for the rust-secp256k1 API is:
- Most functions on `PublicKey` and `SecretKey` now require a
`Secp256k1` to be given to them.
- `Secp256k1::verify` and `::verify_raw` now take a `&self`
- `SecretKey::new` now takes a `Secp256k1` rather than a Rng; a
future commit will allow specifying the Rng in the `Secp256k1`
so that functionality is not lost.
- The FFI functions have all changed to take a context argument
- `secp256k1::init()` is gone, as is the dependency on std::sync
- There is a `ffi::Context` type which must be handled carefully
by anyone using it directly (hopefully nobody :))
rust-secp256k1 was based off of https://github.com/sipa/secp256k1,
which has been inactive nearly as long as this repository (prior to
a couple days ago anyway). The correct repository is
https://github.com/bitcoin/secp256k1
This is a major breaking change to the library for one reason: there
are no longer any Nonce types in the safe interface. The signing functions
do not take a nonce; this is generated internally.
This also means that I was able to drop all my RFC6979 code, since
libsecp256k1 has its own implementation.
If you need to generate your own nonces, you need to create an unsafe
function of type `ffi::NonceFn`, then pass it to the appropriate
functions in the `ffi` module. There is no safe interface for doing
this, deliberately: there is basically no need to directly fiddle
with nonces ever.
Andrew Poelstra