signature: remove derive feature (#1843)

`signature_derive` was used to provide a `Signer` implementation from a
`DigestSigner` and `PrehashSignature` but it does not appears to be used
in any place I can see.

If this becomes to actually be used, we'll then provide a macro-based
implementation for it but I'll hold on to that until we find a consumer.

Author: baloo

.github/workflows/signature.yml

@@ -4,7 +4,6 @@ on:
   pull_request:
     paths:
       - "signature/**"
-      - "signature-derive/**"
       - "Cargo.*"
   push:
     branches: master
@@ -37,9 +36,7 @@ jobs:
           toolchain: ${{ matrix.rust }}
           targets: ${{ matrix.target }}
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features
-      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features derive
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features rand_core
-      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features derive,rand_core
 
   minimal-versions:
     if: false # disabled until we stop using pre-releases
@@ -63,19 +60,3 @@ jobs:
       - run: cargo test --release --no-default-features
       - run: cargo test --release
       - run: cargo test --release --all-features
-
-  derive:
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        rust:
-          - 1.85.0 # MSRV
-          - stable
-    steps:
-      - uses: actions/checkout@v4
-      - uses: RustCrypto/actions/cargo-cache@master
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: ${{ matrix.rust }}
-      - run: cargo test --release
-        working-directory: signature_derive

Cargo.toml

@@ -10,7 +10,6 @@ members = [
     "elliptic-curve",
     "kem",
     "password-hash",
-    "signature_derive",
     "universal-hash",
     "signature",
 ]

signature/CHANGELOG.md

@@ -9,15 +9,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `RandomizedSignerMut` trait ([#1448])
 
 ### Changed
-- Replace `signature_derive` with blanket impls ([#1827])
 - Edition changed to 2024 and MSRV bumped to 1.85 ([#1759])
 
 ### Removed
 - `std` feature - replaced with `core::error::Error`
+- `derive` feature
 
 [#1448]: https://github.com/RustCrypto/traits/pull/1448
 [#1759]: https://github.com/RustCrypto/traits/pull/1759
-[#1827]: https://github.com/RustCrypto/traits/pull/1827
 
 ## 2.2.0 (2023-11-12)
 ### Changed

signature/Cargo.toml

@@ -13,7 +13,6 @@ categories = ["cryptography", "no-std"]
 description = "Traits for cryptographic signature algorithms (e.g. ECDSA, Ed25519)"
 
 [dependencies]
-derive = { package = "signature_derive", version = "2", optional = true, path = "../signature_derive" }
 digest = { version = "=0.11.0-pre.10", optional = true, default-features = false }
 rand_core = { version = "0.9", optional = true, default-features = false }
 

signature/src/lib.rs

@@ -145,12 +145,6 @@ mod prehash_signature;
 
 pub use crate::{encoding::*, error::*, keypair::*, signer::*, verifier::*};
 
-#[cfg(feature = "derive")]
-pub use derive::{Signer, Verifier};
-
-#[cfg(all(feature = "derive", feature = "digest"))]
-pub use derive::{DigestSigner, DigestVerifier};
-
 #[cfg(feature = "digest")]
 pub use {crate::prehash_signature::*, digest};
 

signature/src/prehash_signature.rs

@@ -19,11 +19,6 @@ use crate::{
 /// This approach is relatively common in signature schemes based on the
 /// [Fiat-Shamir heuristic].
 ///
-/// For signature types that implement this trait, when the `derive` crate
-/// feature is enabled a custom derive for [`Signer`] is available for any
-/// types that impl [`DigestSigner`], and likewise for deriving [`Verifier`] for
-/// types which impl [`DigestVerifier`].
-///
 /// [Fiat-Shamir heuristic]: https://en.wikipedia.org/wiki/Fiat%E2%80%93Shamir_heuristic
 pub trait PrehashSignature {
     /// Preferred `Digest` algorithm to use when computing this signature type.