mirror of
https://github.com/saymrwulf/curve25519-dalek-source.git
synced 2026-09-04 20:24:10 +00:00
Rework backend selection code.
Each backend can now be selected by an individual feature: - `u32_backend` for `backend::u32`; - `u64_backend` for `backend::u64`; - `avx2_backend` for `backend::avx2`; The `u64_backend` is selected by default, since most people use X64 and we have no way to select based on target (see discussion in #126). However, these changes mean that it is possible to select the backend explicitly, and if we had the ability to select target-default features, we could do so easily.
This commit is contained in:
Henry de Valence
parent
9b6c932635
commit
34c43c20a9
10 changed files with 70 additions and 60 deletions
28
.travis.yml
28
.travis.yml
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@ -2,34 +2,28 @@ language: rust
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rust:
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- stable
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- beta
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- nightly
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env:
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- TEST_COMMAND=test EXTRA_FLAGS='' FEATURES=''
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# Tests the u32 backend
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- TEST_COMMAND=test EXTRA_FLAGS='--no-default-features' FEATURES='std u32_backend'
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# Tests the u64 backend
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- TEST_COMMAND=test EXTRA_FLAGS='--no-default-features' FEATURES='std u64_backend'
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# Tests the avx2 backend
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- TEST_COMMAND=test EXTRA_FLAGS='--no-default-features' FEATURES='std avx2_backend yolocrypto'
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# Tests serde support and default feature selection
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- TEST_COMMAND=test EXTRA_FLAGS='' FEATURES='serde'
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- TEST_COMMAND=test EXTRA_FLAGS='' FEATURES='nightly'
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- TEST_COMMAND=test EXTRA_FLAGS='' FEATURES='yolocrypto nightly'
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# Tests building without std
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- TEST_COMMAND=build EXTRA_FLAGS=--no-default-features FEATURES=''
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matrix:
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exclude:
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# Test nightly features, such as radix_51, only on nightly.
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# Test the avx2 backend only on nightly
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- rust: stable
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env: TEST_COMMAND=test EXTRA_FLAGS='' FEATURES='nightly'
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- rust: beta
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env: TEST_COMMAND=test EXTRA_FLAGS='' FEATURES='nightly'
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- rust: stable
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env: TEST_COMMAND=test EXTRA_FLAGS='' FEATURES='yolocrypto nightly'
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- rust: beta
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env: TEST_COMMAND=test EXTRA_FLAGS='' FEATURES='yolocrypto nightly'
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env: TEST_COMMAND=test EXTRA_FLAGS='--no-default-features' FEATURES='std avx2_backend yolocrypto'
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# Test no_std only on nightly.
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- rust: stable
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env: TEST_COMMAND=build EXTRA_FLAGS=--no-default-features FEATURES=''
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- rust: beta
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env: TEST_COMMAND=build EXTRA_FLAGS=--no-default-features FEATURES=''
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- rust: nightly
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env: TEST_COMMAND=build EXTRA_FLAGS=--no-default-features FEATURES='alloc'
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env: TEST_COMMAND=build EXTRA_FLAGS=--no-default-features FEATURES=''
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script:
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- cargo $TEST_COMMAND --features="$FEATURES" $EXTRA_FLAGS
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19
Cargo.toml
19
Cargo.toml
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@ -60,15 +60,20 @@ serde = { version = "1.0", optional = true }
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rand = { version = "0.4", optional = false }
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[features]
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nightly = ["radix_51", "subtle/nightly", "clear_on_drop/nightly"]
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default = ["std"]
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nightly = ["subtle/nightly", "clear_on_drop/nightly"]
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default = ["std", "u64_backend"]
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std = ["rand", "subtle/std"]
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alloc = []
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yolocrypto = ["avx2_backend"]
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# Radix-51 arithmetic using u128
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radix_51 = []
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# experimental avx2 support
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avx2_backend = ["nightly"]
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yolocrypto = []
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# The u32 backend uses u32s with u64 products.
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u32_backend = []
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# The u64 backend uses u64s with u128 products.
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u64_backend = []
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# The AVX2 backend uses u32x8s with u64x4 products.
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# It uses the u64 code for serial operations.
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avx2_backend = ["nightly", "u64_backend"]
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# Signals that we're in the main build stage. This is off by default,
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# to signal stage 1 of the build, where build.rs loads the library
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# into the build script. Then, the build.rs emits the stage2_build
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29
README.md
29
README.md
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@ -59,25 +59,38 @@ extern crate curve25519_dalek;
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# Backends and Features
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The `yolocrypto` feature enables experimental features. The name `yolocrypto`
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is meant to indicate that it is not considered production-ready, and we do not
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consider `yolocrypto` features to be covered by semver guarantees.
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The `std` feature is enabled by default, but it can be disabled.
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The `nightly` feature enables nightly-only features. **It is recommended for security**.
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Curve arithmetic is implemented using one of the following backends:
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* a `u32` backend using `u64` products;
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* a `u64` backend using `u128` products, available using the `nightly` feature;
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* a `u64` backend using `u128` products;
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* an experimental AVX2 backend, available using the `yolocrypto` feature when
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compiling for a target with `target_feature=+avx2`.
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By default the `u64` backend is selected. To select a specific backend, use:
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```sh
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cargo build --no-default-features --features "std u32_backend"
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cargo build --no-default-features --features "std u64_backend"
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cargo build --no-default-features --features "std avx2_backend yolocrypto"
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```
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Benchmarks are run using [`criterion.rs`][criterion]:
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```sh
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cargo bench # u32 backend
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cargo bench --features="nightly" # u64 backend
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cargo bench --features="nightly yolocrypto" # u64 or avx2 if available
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# You must set RUSTFLAGS to enable AVX2 support.
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export RUSTFLAGS="-C target_cpu=native"
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cargo bench --no-default-features --features "std u32_backend"
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cargo bench --no-default-features --features "std u64_backend"
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cargo bench --no-default-features --features "std avx2_backend yolocrypto"
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```
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The `yolocrypto` feature enables experimental features. The name `yolocrypto`
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is meant to indicate that it is not considered production-ready, and we do not
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consider `yolocrypto` features to be covered by semver guarantees.
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# Contributing
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Please see [CONTRIBUTING.md][contributing].
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9
build.rs
9
build.rs
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@ -1,4 +1,3 @@
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#![cfg_attr(feature = "nightly", feature(i128_type))]
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#![cfg_attr(feature = "nightly", feature(cfg_target_feature))]
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#![cfg_attr(all(feature = "nightly", feature = "yolocrypto"), feature(stdsimd))]
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#![allow(unused_variables)]
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@ -75,12 +74,12 @@ fn main() {
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f.write_all(
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format!(
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"\n
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#[cfg(feature=\"radix_51\")]
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use backend::u64::field::FieldElement64;
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#[cfg(not(feature=\"radix_51\"))]
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#[cfg(feature = \"u32_backend\")]
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use backend::u32::field::FieldElement32;
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#[cfg(feature = \"u64_backend\")]
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use backend::u64::field::FieldElement64;
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use edwards::EdwardsBasepointTable;
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use curve_models::AffineNielsPoint;
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@ -21,12 +21,12 @@
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//! `32bit` since identifiers can't start with letters, and the backends
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//! do use `u32`/`u64`, so this seems like a least-bad option.
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#[cfg(not(feature="radix_51"))]
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#[cfg(feature = "u32_backend")]
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pub mod u32;
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#[cfg(feature="radix_51")]
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#[cfg(feature = "u64_backend")]
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pub mod u64;
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#[cfg(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2")))]
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#[cfg(all(feature = "avx2_backend", feature = "yolocrypto", target_feature = "avx2"))]
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pub mod avx2;
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@ -33,9 +33,9 @@ use ristretto::CompressedRistretto;
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use montgomery::MontgomeryPoint;
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use scalar::Scalar;
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#[cfg(feature="radix_51")]
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#[cfg(feature = "u64_backend")]
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pub use backend::u64::constants::*;
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#[cfg(not(feature="radix_51"))]
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#[cfg(feature = "u32_backend")]
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pub use backend::u32::constants::*;
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/// The Ed25519 basepoint, in `CompressedEdwardsY` format.
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@ -149,8 +149,8 @@ mod test {
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}
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/// Test that d = -121665/121666
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#[cfg(not(feature="radix_51"))]
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#[test]
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#[cfg(feature = "u32_backend")]
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fn test_d_vs_ratio() {
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use backend::u32::field::FieldElement32;
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let a = -&FieldElement32([121665,0,0,0,0,0,0,0,0,0]);
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@ -162,8 +162,8 @@ mod test {
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}
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/// Test that d = -121665/121666
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#[cfg(feature="radix_51")]
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#[test]
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#[cfg(feature = "u64_backend")]
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fn test_d_vs_ratio() {
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use backend::u64::field::FieldElement64;
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let a = -&FieldElement64([121665,0,0,0,0]);
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@ -490,13 +490,13 @@ impl<'a, 'b> Mul<&'b Scalar> for &'a EdwardsPoint {
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/// `EdwardsBasepointTable` is approximately 4x faster.
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fn mul(self, scalar: &'b Scalar) -> EdwardsPoint {
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// If we built with AVX2, use the AVX2 backend.
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#[cfg(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2")))]
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#[cfg(all(feature="avx2_backend", target_feature="avx2"))]
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{
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use backend::avx2::scalar_mul::variable_base::mul;
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mul(self, scalar)
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}
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// Otherwise, use the serial backend:
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#[cfg(not(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2"))))]
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#[cfg(not(all(feature="avx2_backend", target_feature="avx2")))]
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{
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use scalar_mul::variable_base::mul;
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mul(self, scalar)
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@ -571,13 +571,13 @@ pub fn multiscalar_mul<I, J>(scalars: I, points: J) -> EdwardsPoint
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// delegate based on the iter's size hint -- hdevalence
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// If we built with AVX2, use the AVX2 backend.
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#[cfg(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2")))]
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#[cfg(all(feature="avx2_backend", target_feature="avx2"))]
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{
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use backend::avx2::scalar_mul::straus::multiscalar_mul;
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multiscalar_mul(scalars, points)
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}
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// Otherwise, proceed as normal:
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#[cfg(not(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2"))))]
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#[cfg(not(all(feature="avx2_backend", target_feature="avx2")))]
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{
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use scalar_mul::straus::multiscalar_mul;
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multiscalar_mul(scalars, points)
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@ -844,13 +844,13 @@ pub mod vartime {
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// XXX later when we do more fancy multiscalar mults, we can delegate
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// based on the iter's size hint -- hdevalence
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// If we built with AVX2, use the AVX2 backend.
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#[cfg(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2")))]
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#[cfg(all(feature="avx2_backend", target_feature="avx2"))]
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{
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use backend::avx2::scalar_mul::vartime_straus::multiscalar_mul;
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multiscalar_mul(scalars, points)
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}
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// Otherwise, proceed as normal:
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#[cfg(not(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2"))))]
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#[cfg(not(all(feature="avx2_backend", target_feature="avx2")))]
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{
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use scalar_mul::vartime_straus::multiscalar_mul;
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multiscalar_mul(scalars, points)
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@ -861,13 +861,13 @@ pub mod vartime {
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#[cfg(feature="stage2_build")]
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pub fn double_scalar_mul_basepoint(a: &Scalar, A: &EdwardsPoint, b: &Scalar) -> EdwardsPoint {
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// If we built with AVX2, use the AVX2 backend.
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#[cfg(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2")))]
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#[cfg(all(feature="avx2_backend", target_feature="avx2"))]
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{
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use backend::avx2::scalar_mul::vartime_double_base::mul;
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mul(a, A, b)
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}
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// Otherwise, proceed as normal:
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#[cfg(not(all(feature="nightly", all(feature="avx2_backend", target_feature="avx2"))))]
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#[cfg(not(all(feature="avx2_backend", target_feature="avx2")))]
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{
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use scalar_mul::vartime_double_base::mul;
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mul(a, A, b)
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@ -1169,7 +1169,7 @@ mod test {
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/// and enable `debug_assert!()`. This performs many scalar
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/// multiplications to attempt to trigger possible overflows etc.
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///
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/// For instance, the `radix_51` `Mul` implementation for
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/// For instance, the `u64` `Mul` implementation for
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/// `FieldElements` requires the input `Limb`s to be bounded by
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/// 2^54, but we cannot enforce this dynamically at runtime, or
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/// statically at compile time (until Rust gets type-level
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@ -32,24 +32,24 @@ use subtle::ConstantTimeEq;
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use constants;
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use backend;
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#[cfg(feature="radix_51")]
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#[cfg(feature = "u64_backend")]
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pub use backend::u64::field::*;
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/// A `FieldElement` represents an element of the field
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/// \\( \mathbb Z / (2\^{255} - 19)\\).
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///
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/// The `FieldElement` type is an alias for one of the platform-specific
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/// implementations.
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#[cfg(feature="radix_51")]
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#[cfg(feature = "u64_backend")]
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pub type FieldElement = backend::u64::field::FieldElement64;
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#[cfg(not(feature="radix_51"))]
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#[cfg(feature = "u32_backend")]
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pub use backend::u32::field::*;
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/// A `FieldElement` represents an element of the field
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/// \\( \mathbb Z / (2\^{255} - 19)\\).
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///
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/// The `FieldElement` type is an alias for one of the platform-specific
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/// implementations.
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#[cfg(not(feature="radix_51"))]
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#[cfg(feature = "u32_backend")]
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pub type FieldElement = backend::u32::field::FieldElement32;
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impl Eq for FieldElement {}
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@ -12,7 +12,6 @@
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#![cfg_attr(feature = "alloc", feature(alloc))]
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#![cfg_attr(feature = "nightly", feature(i128_type))]
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#![cfg_attr(feature = "nightly", feature(cfg_target_feature))]
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#![cfg_attr(feature = "nightly", feature(external_doc))]
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#![cfg_attr(all(feature = "nightly", feature = "yolocrypto"), feature(stdsimd))]
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@ -39,14 +39,14 @@ use constants;
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///
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/// This is a type alias for one of the scalar types in the `backend`
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/// module.
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#[cfg(feature="radix_51")]
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#[cfg(feature = "u64_backend")]
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type UnpackedScalar = backend::u64::scalar::Scalar64;
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/// An `UnpackedScalar` represents an element of the field GF(l), optimized for speed.
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///
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/// This is a type alias for one of the scalar types in the `backend`
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/// module.
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#[cfg(not(feature="radix_51"))]
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#[cfg(feature = "u32_backend")]
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type UnpackedScalar = backend::u32::scalar::Scalar32;
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Reference in a new issue