Fast and efficient Rust implementation of ed25519 key generation, signing, and verification in Rust.
Documentation is available here.
On an Intel Skylake i9-7900X running at 3.30 GHz, without TurboBoost, this code achieves the following performance benchmarks:
∃!isisⒶmistakenot:(master *=)~/code/rust/ed25519-dalek ∴ cargo bench Compiling ed25519-dalek v0.7.0 (file:///home/isis/code/rust/ed25519-dalek) Finished release [optimized] target(s) in 3.11s Running target/release/deps/ed25519_benchmarks-721332beed423bce Ed25519 signing time: [15.617 us 15.630 us 15.647 us] Ed25519 signature verification time: [45.930 us 45.968 us 46.011 us] Ed25519 keypair generation time: [15.440 us 15.465 us 15.492 us]
By enabling the avx2 backend (on machines with compatible microarchitectures), the performance for signature verification is greatly improved:
∃!isisⒶmistakenot:(master *=)~/code/rust/ed25519-dalek ∴ export RUSTFLAGS=-Ctarget_cpu=native ∃!isisⒶmistakenot:(master *=)~/code/rust/ed25519-dalek ∴ cargo bench --features=avx2_backend Compiling ed25519-dalek v0.7.0 (file:///home/isis/code/rust/ed25519-dalek) Finished release [optimized] target(s) in 4.28s Running target/release/deps/ed25519_benchmarks-e4866664de39c84d Ed25519 signing time: [15.923 us 15.945 us 15.967 us] Ed25519 signature verification time: [33.382 us 33.411 us 33.445 us] Ed25519 keypair generation time: [15.246 us 15.260 us 15.275 us]
In comparison, the equivalent package in Golang performs as follows:
∃!isisⒶmistakenot:(master *=)~/code/go/src/github.com/agl/ed25519 ∴ go test -bench . BenchmarkKeyGeneration 30000 47007 ns/op BenchmarkSigning 30000 48820 ns/op BenchmarkVerification 10000 119701 ns/op ok github.com/agl/ed25519 5.775s
Making key generation and signing a rough average of 2x faster, and verification 2.5-3x faster depending on the availability of avx2. Of course, this is just my machine, and these results—nowhere near rigorous—should be taken with a handful of salt.
Translating to a rough cycle count: we multiply by a factor of 3.3 to convert nanoseconds to cycles per second on a 3300 Mhz CPU, that's 110256 cycles for verification and 52618 for signing, which is competitive with hand-optimised assembly implementations.
Additionally, if you're using a CSPRNG from the
rand crate, the
feature will enable
i128 features there, resulting in potentially
If your protocol or application is able to batch signatures for verification,
verify_batch() function has greatly improved performance. On the
aforementioned Intel Skylake i9-7900X, verifying a batch of 96 signatures takes
1.7673ms. That's 18.4094us, or roughly 60750 cycles, per signature verification,
more than double the speed of batch verification given in the original paper
(this is likely not a fair comparison as that was a Nehalem machine).
The numbers after the
/ in the test name refer to the size of the batch:
∃!isisⒶmistakenot:(master *=)~/code/rust/ed25519-dalek ∴ export RUSTFLAGS=-Ctarget_cpu=native ∃!isisⒶmistakenot:(master *=)~/code/rust/ed25519-dalek ∴ cargo bench --features=avx2_backend batch Compiling ed25519-dalek v0.8.0 (file:///home/isis/code/rust/ed25519-dalek) Finished release [optimized] target(s) in 34.16s Running target/release/deps/ed25519_benchmarks-cf0daf7d68fc71b6 Ed25519 batch signature verification/4 time: [105.20 us 106.04 us 106.99 us] Ed25519 batch signature verification/8 time: [178.66 us 179.01 us 179.39 us] Ed25519 batch signature verification/16 time: [325.65 us 326.67 us 327.90 us] Ed25519 batch signature verification/32 time: [617.96 us 620.74 us 624.12 us] Ed25519 batch signature verification/64 time: [1.1862 ms 1.1900 ms 1.1943 ms] Ed25519 batch signature verification/96 time: [1.7611 ms 1.7673 ms 1.7742 ms] Ed25519 batch signature verification/128 time: [2.3320 ms 2.3376 ms 2.3446 ms] Ed25519 batch signature verification/256 time: [5.0124 ms 5.0290 ms 5.0491 ms]
As you can see, there's an optimal batch size for each machine, so you'll likely want to your the benchmarks on your target CPU to discover the best size. For this machine, around 100 signatures per batch is the optimum:
Additionally, thanks to Rust, this implementation has both type and memory safety. It's also easily readable by a much larger set of people than those who can read qhasm, making it more readily and more easily auditable. We're of the opinion that, ultimately, these features—combined with speed—are more valuable than simply cycle counts alone.
A Note on Signature Malleability
The signatures produced by this library are malleable, as discussed in the original paper:
We could eliminate the malleability property by multiplying by the curve cofactor, however, this would cause our implementation to not match the behaviour of every other implementation in existence. As of this writing, RFC 8032, "Edwards-Curve Digital Signature Algorithm (EdDSA)," advises that the stronger check should be done. While we agree that the stronger check should be done, it is our opinion that one shouldn't get to change the definition of "ed25519 verification" a decade after the fact, breaking compatibility with every other implementation.
In short, if malleable signatures are bad for your protocol, don't use them. Consider using a curve25519-based Verifiable Random Function (VRF), such as Trevor Perrin's VXEdDSA, instead. We plan to eventually support VXEdDSA in curve25519-dalek.
To install, add the following to your project's
[dependencies.ed25519-dalek] version = "1"
Then, in your library or executable source, add:
extern crate ed25519_dalek;
To cause your application to build
ed25519-dalek with the nightly feature
enabled by default, instead do:
[dependencies.ed25519-dalek] version = "1" features = ["nightly"]
To cause your application to instead build with the nightly feature enabled
when someone builds with
cargo build --features="nightly" add the following
[features] nightly = ["ed25519-dalek/nightly"]
To enable serde support, build
[dependencies.ed25519-dalek] version = "1" features = ["serde"]
ed25519-dalek builds against
feature, which uses Rust's
i128 feature to achieve roughly double the speed as
u32_backend feature. When targetting 32-bit systems, however, you'll
likely want to compile with
cargo build --no-default-features --features="u32_backend".
If you're building for a machine with avx2 instructions, there's also the
avx2_backend. To use it, compile with
RUSTFLAGS="-C target_cpu=native" cargo build --no-default-features --features="avx2_backend"