p384: rename arithmetic feature to broken-arithmetic-do-not-use (#513)

The arithmetic implementations as they currently exist are known to be
broken, so to prevent someone from accidentally attempting to use them
unknowingly, renames the feature to `broken-arithmetic-do-not-use`.

Additionally removes the derived `invert` and `sqrt` methods.

Author: tarcieri

.github/workflows/p384.yml

@@ -37,6 +37,8 @@ jobs:
           override: true
           profile: minimal
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features
+      # TODO(tarcieri): currently 64-bit only
+      # - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features broken-arithmetic-do-not-use
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features ecdsa
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features jwk
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features pem

README.md

@@ -14,11 +14,11 @@ and can be easily used for bare-metal or WebAssembly programming.
 
 | Name      | Curve              | `arithmetic`? | Crates.io | Documentation | Build Status |
 |-----------|--------------------|---------------|-----------|---------------|--------------|
-| [`bp256`] | brainpoolP256r1/t1 | 🚫 | [![crates.io](https://img.shields.io/crates/v/bp256.svg)](https://crates.io/crates/bp256) | [![Documentation](https://docs.rs/bp256/badge.svg)](https://docs.rs/bp256) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/bp256/badge.svg?branch=master&event=push) |
-| [`bp384`] | brainpoolP384r1/t1 | 🚫 | [![crates.io](https://img.shields.io/crates/v/bp384.svg)](https://crates.io/crates/bp384) | [![Documentation](https://docs.rs/bp384/badge.svg)](https://docs.rs/bp384) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/bp384/badge.svg?branch=master&event=push) |
-| [`k256`]  | [secp256k1]        | ✅ | [![crates.io](https://img.shields.io/crates/v/k256.svg)](https://crates.io/crates/k256) | [![Documentation](https://docs.rs/k256/badge.svg)](https://docs.rs/k256) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/k256/badge.svg?branch=master&event=push) |
-| [`p256`]  | [NIST P-256]       | ✅ | [![crates.io](https://img.shields.io/crates/v/p256.svg)](https://crates.io/crates/p256) | [![Documentation](https://docs.rs/p256/badge.svg)](https://docs.rs/p256) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/p256/badge.svg?branch=master&event=push) |
-| [`p384`]  | [NIST P-384]       | 🚫 | [![crates.io](https://img.shields.io/crates/v/p384.svg)](https://crates.io/crates/p384) | [![Documentation](https://docs.rs/p384/badge.svg)](https://docs.rs/p384) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/p384/badge.svg?branch=master&event=push) |
+| [`bp256`] | brainpoolP256r1/t1 | 🚫            | [![crates.io](https://img.shields.io/crates/v/bp256.svg)](https://crates.io/crates/bp256) | [![Documentation](https://docs.rs/bp256/badge.svg)](https://docs.rs/bp256) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/bp256/badge.svg?branch=master&event=push) |
+| [`bp384`] | brainpoolP384r1/t1 | 🚫            | [![crates.io](https://img.shields.io/crates/v/bp384.svg)](https://crates.io/crates/bp384) | [![Documentation](https://docs.rs/bp384/badge.svg)](https://docs.rs/bp384) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/bp384/badge.svg?branch=master&event=push) |
+| [`k256`]  | [secp256k1]        | ✅            | [![crates.io](https://img.shields.io/crates/v/k256.svg)](https://crates.io/crates/k256) | [![Documentation](https://docs.rs/k256/badge.svg)](https://docs.rs/k256) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/k256/badge.svg?branch=master&event=push) |
+| [`p256`]  | [NIST P-256]       | ✅            | [![crates.io](https://img.shields.io/crates/v/p256.svg)](https://crates.io/crates/p256) | [![Documentation](https://docs.rs/p256/badge.svg)](https://docs.rs/p256) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/p256/badge.svg?branch=master&event=push) |
+| [`p384`]  | [NIST P-384]       | 🚧            | [![crates.io](https://img.shields.io/crates/v/p384.svg)](https://crates.io/crates/p384) | [![Documentation](https://docs.rs/p384/badge.svg)](https://docs.rs/p384) | ![build](https://github.com/RustCrypto/elliptic-curves/workflows/p384/badge.svg?branch=master&event=push) |
 
 NOTE: Some crates contain field/point arithmetic implementations gated under the
 `arithmetic` cargo feature as noted above.

p384/Cargo.toml

@@ -23,7 +23,7 @@ hex-literal = "0.3"
 
 [features]
 default = ["pkcs8", "std"]
-arithmetic = ["elliptic-curve/arithmetic"]
+broken-arithmetic-do-not-use = ["elliptic-curve/arithmetic"]
 jwk = ["elliptic-curve/jwk"]
 pem = ["elliptic-curve/pem", "pkcs8"]
 pkcs8 = ["elliptic-curve/pkcs8"]

p384/src/arithmetic/affine.rs

@@ -34,7 +34,7 @@ impl AffineArithmetic for NistP384 {
 ///
 /// [SEC1]: https://www.secg.org/sec1-v2.pdf
 #[derive(Clone, Copy, Debug)]
-#[cfg_attr(docsrs, doc(cfg(feature = "arithmetic")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "broken-arithmetic-do-not-use")))]
 pub struct AffinePoint {
     pub(crate) x: FieldElement,
     pub(crate) y: FieldElement,