elliptic-curve: remove bits feature

.github/workflows/elliptic-curve.yml

@@ -46,7 +46,6 @@ jobs:
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features alloc
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features arithmetic
-      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features bits
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features critical-section
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features dev
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features digest
@@ -104,6 +103,6 @@ jobs:
       - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
         with:
-          toolchain: nightly-2026-02-11 # pinned due to rust-lang/miri#4855
+          toolchain: nightly-2026-05-01 # pinned due to ensure determinism
       - run: rustup component add miri && cargo miri setup
       - run: cargo miri test --all-features

elliptic-curve/Cargo.toml

@@ -36,7 +36,6 @@ pem-rfc7468 = { version = "1", optional = true, features = ["alloc"] }
 pkcs8 = { version = "0.11", optional = true, default-features = false }
 sec1 = { version = "0.8", optional = true, features = ["ctutils", "subtle", "zeroize"] }
 serdect = { version = "0.4", optional = true, default-features = false, features = ["alloc"] }
-tap = { version = "1.0.1", optional = true, default-features = false } # make `bitvec`'s `wyz` work with `minimal-versions`
 
 [dev-dependencies]
 hex-literal = "1"
@@ -62,7 +61,6 @@ std = [
 arithmetic = ["group"]
 basepoint-table = ["arithmetic"]
 critical-section = ["basepoint-table", "once_cell/critical-section"]
-bits = ["dep:tap", "arithmetic", "ff/bits"]
 dev = ["arithmetic", "dep:hex-literal", "pem", "pkcs8"]
 ecdh = ["arithmetic", "digest", "dep:hkdf"]
 getrandom = ["arithmetic", "bigint/getrandom", "common/getrandom"]

elliptic-curve/src/dev/mock_curve.rs

@@ -31,8 +31,6 @@ use pkcs8::AssociatedOid;
 
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
-#[cfg(feature = "bits")]
-use ff::PrimeFieldBits;
 
 /// Pseudo-coordinate for fixed-based scalar mult output
 pub const PSEUDO_COORDINATE_FIXED_BASE_MUL: [u8; 32] =
@@ -56,10 +54,6 @@ pub type SecretKey = crate::SecretKey<MockCurve>;
 /// Scalar value type.
 pub type ScalarValue = crate::ScalarValue<MockCurve>;
 
-/// Scalar bits.
-#[cfg(feature = "bits")]
-pub type ScalarBits = crate::scalar::ScalarBits<MockCurve>;
-
 /// Mock elliptic curve type useful for writing tests which require a concrete
 /// curve type.
 ///
@@ -161,23 +155,6 @@ impl PrimeField for Scalar {
     }
 }
 
-#[cfg(feature = "bits")]
-impl PrimeFieldBits for Scalar {
-    #[cfg(target_pointer_width = "32")]
-    type ReprBits = [u32; 8];
-
-    #[cfg(target_pointer_width = "64")]
-    type ReprBits = [u64; 4];
-
-    fn to_le_bits(&self) -> ScalarBits {
-        self.0.as_uint().to_words().into()
-    }
-
-    fn char_le_bits() -> ScalarBits {
-        MockCurve::ORDER.to_words().into()
-    }
-}
-
 impl Generate for Scalar {
     fn try_generate_from_rng<R: TryCryptoRng + ?Sized>(
         rng: &mut R,

elliptic-curve/src/scalar.rs

@@ -21,10 +21,6 @@ use crate::CurveArithmetic;
 #[cfg(feature = "arithmetic")]
 pub type Scalar<C> = <C as CurveArithmetic>::Scalar;
 
-/// Bit representation of a scalar field element of a given curve.
-#[cfg(feature = "bits")]
-pub type ScalarBits<C> = ff::FieldBits<<Scalar<C> as ff::PrimeFieldBits>::ReprBits>;
-
 /// Instantiate a scalar from an unsigned integer without checking for overflow.
 pub trait FromUintUnchecked {
     /// Unsigned integer type (i.e. `Curve::Uint`)