rust-bitcoin

Implement Serde traits for ArrayVec

This implementation is a prerequisite for the serde traits
impl for `WitnessVersion` and `WitnessProgram`.

Add tests covering round-trip serialization, capacity overflow errors,
and wire-format compatibilitywith slices using both JSON and Bincode.

fuzz: remove psbt fuzz targets and document explicit local bitcoin dependency

crypto: Change to_public_key to return FullPublicKey

In general, modern bitcoin code should be using either the compressed
FullPublicKey or the XOnlyPublicKey. Users should try to avoid the
legacy optionally-compressed public key. To this end, the types were
renamed. To further consolidate this, the to_public_key methods
throughout the key module should also return FullPublicKey, with the
existing behaviour relegated to new to_legacy_public_key.

Change all to_public_key functions to return FullPublicKey and
introduce corresponding to_legacy_public_key functions to return
LegacyPublicKey where necessary.

crypto: Remove unused test from ecdsa

In ecdsa, the write_serialized_signature test was used to test the
serialize_to_writer method on the ecdsa::Signature. Since this was
removed as part of the bitcoin-io dep removal, the test should also
be removed.

Remove write_serialized_signature test case from ecdsa tests module.

crypto: Bump version to 0.2.0

Bump the `crypto` version. Update the dep in `bitcoin` and add an
explicit version number in `taproot-primitives`.

In preparation add a changelog entry, bump the version number, and
update the lock files.

Delete psbt module

In #6055 we deprecated the `psbt` module on the `0.32.x` branch. Now
we can delete it from master.

### Context

Development of the PSBT has moved to a separate crate. Hosted on the
new Forgejo instance at:

https://git.rust-bitcoin.org/rust-bitcoin/rust-psbt

Crate name is `psbt-v2` because it has initial support for PSBTv2. The
crate also includes all code from the `0.32.x` branch (as well as
miniscript code). In other words the crate is a drop in replacement
for the `Psbt` type and its functionality.

During release of `psbt-v2 v0.3.0` we attempted to ensure feature
parity with `0.32.x` since the actual migration was done a while back.

The road map for dev of `psbt-v2` is loosely:

- Improve PSBTv2 stuff
- Continue work on supporting Silent Payments
- Use crate as a test bed for the process of upgrade of `bitcoin 0.32.x`


Exact strategy of the last point is being worked on. We are
investigating creating a bunch of step-by-step releases to help the
process. To prove (and develop) the process we plan on using:

- miniscript
- psbt-v2
- corepc

hashes: Add x86 AVX2 8-way dispatch

add dispatcher that handles 8-way

hashes: fold 8-way AVX2 SHA256d into round! macro

use a round! macro to cut ~1060 lines from the unrolled version.
each round becomes a single round!(...) call that almost matches
Core's Transform_8way line-by-line, so it's easy to compare and
review against sha256_avx2.cpp.

refactor, no behavior change.

hashes: Add 8-way AVX2 SHA256d for 64-byte input

add the three transforms for sha256(sha256(64_bytes)) using AVX2
SIMD.

AVX2 uses 256-bit registers, so we can pack eight 32-bit words into
each register and compute 8 independent hashes in parallel with a
single SIMD op.

- Transforms 1 & 2 compute the inner `sha256(64_bytes)`.
- Transform 3 computes sha256(output_of_T1_and_T2).

rounds are fully unrolled (we will use a round! macro to fold them
in the next patch).

Run the formatter

Use drain instead of flush

The term 'flush' has meaning already in respect to a std writer thus
impiles that a function with 'flush' in the name would call
`writer.flush()` but we do not.

After debate we reached consensus on the verb 'drain' to replace
'flush'.

Rename all 'flush_to_writer' functions to be `drain_to_writer`
repository wide. To keep our API uniform also re-name `flush_to_vec`
to be `drain_to_vec`.

crypto: Remove bitcoin-io dependency

With the removal of the io-dependent functions from the key and
signature types, the bitcoin-io dependency can be entirely dropped from
the crypto crate.

Remove bitcoin-io dependency from manifest and update lock files.
Remove io re-export from crate root.

Remove io methods on public key types

The read_from and write_into functions on the public key types rely on
the bitcoin-io Read and Write traits. Since we want to remove the
dependence on io for the crypto crate, these methods must also be
removed. With the Serialized* types, the write_into methods are trivial
to replace inline.

Remove read_from and write_into methods from public key types and test
case for them.

hashes: change engine parameter to be mutable reference

Allow engine parameter to be less restrictive in use. By changing the
parameter to `&mut`, the calling function no longer needs give up
ownership of engine.

The return value is removed since the caller can simply use existing
ownership of variable instead of the return value.

hashes: Add 4-way dispatcher

add x86 sha256d dispatcher that handles 4-way SSE4.1

hashes: fold 4-way SSE4.1 SHA256d into round! macro

use a round! macro to cut ~1000 lines from the unrolled version.
each round becomes a single round!(...) call. it almost matches Core
line-by-line, so it's easy to compare and review against sha256_sse41.cpp.

refactor, no behavior change.

hashes: Add 4-way SSE4.1 SHA256d for 64-byte input

add the three transforms for sha256(sha256(64_bytes)) using SSE4.1 SIMD.

SSE4.1 uses 128-bit registers, so we can pack four 32-bit words into
each register and compute 4 independent hashes in parallel with a
single SIMD op.

- Transforms 1 & 2 compute the inner `sha256(64_bytes)`.
- Transform 3 computes sha256(output_of_T1_and_T2).

rounds are fully unrolled (we will use a round! macro to fold them
in the next patch).

crypto: Adjust SerializedLegacyPublicKey docs

The SerializedLegacyPublicKey docs don't mention the maximum size or
the lack of allocations like the ecdsa::SerializedSignature docs do.

Adjust wording of docs to mention lack of allocation and max size of
65 bytes.

Remove io write helpers from ecdsa signatures

In the ecdsa module, the SerializedSignature and Signature types have
helper methods for writing to bitcoin-io Write objects. Since we want
to remove the io dependency entirely, and the SerializedSignature can
already be used in a similar way to a slice, there's no point to
retaining them.

Remove Signature::serialize_to_writer and SerializedSignature::write_to.
Adjust existing io test case to use std traits.

Don't abuse psbt Deserialize

I'm not sure what is the intention of this code or exactly how the
derives are working in the `taproot` module because we are importing
`psbt::serialize::Deserialize` and then using it in `serde` derives?

Also the `TapTree` arbitrary stuff is a bit odd, that is what led me
here while I was attempting to delete the `psbt` module.

So, I don't know if this is a bug or an internal change? Introduced in
commit: `37c9fce2a684 Implement `Arbitrary` for psbt types`.

crypto: Move SerializedLegacyPublicKey to crypto

Now that the SerializedLegacyPublicKey has been re-arranged to remove
the strict dependence on PushBytes, it can be trivially moved to the
crypto crate.

Move SerializedLegacyPublicKey to crypto crate and re-export from
bitcoin.
Move associated test to crypto key module.

Remove dependence on PushBytes for SerializedLegacyPublicKey

The SerializedLegacyPublicKey type currently relies on
Borrow<PushBytes> to implement the Borrow and AsRef for [u8]. Since
PushBytes is only in bitcoin, this prevents the simple move. Instead,
the main reference conversion should be Deref for [u8].

Move Deref impl into encapsulating module and redefine
Borrow<PushBytes> in terms of it. Adjust order of Borrow and AsRef
impls.

crypto: Remove error conversion From impls

From impls for conversions between error types represent a public api
commitment. Since we can't know how the error types may need to change
as the crate progresses, it's best to remove these now and reintroduce
them later if we find them necessary and/or useful for users.

Remove all From<BarError> for FooError in crypto, replacing uses with
map_err where appropriate.

crypto: Re-export key types at crate root

Re-export the key types at the crate root, similar to the re-exports in
bitcoin.

crypto: Add pub extern crate for crates with public api types

In crypto, various types from child crates are present in the public
api, including base58::Error, network::NetworkKind, secp256k1 keys and
io traits. In order to simplify dependency handling, these crates
should be exposed through pub extern crate exports in the root of the
crypto crate.

Add pub extern crate statements for base58, network, io and secp256k1.
Remove comment on hex_stable re-export to match new policy.