ed25519-dalek 0.7.0

Fast and efficient ed25519 EdDSA key generations, signing, and verification in pure Rust.


Fast and efficient Rust implementation of ed25519 key generation, signing, and verification in Rust.


Documentation is available here.


You need to pass the --features="bench" flag to run the benchmarks. The reason for feature-gating the benchmarks is that Rust's test::Bencher is unstable, and thus only works on the nightly channel. (We'd like people to be able to compile and test on the stable and beta channels too!)

On an Intel 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="-C target_cpu=native"
∃!isisⒶmistakenot:(master *=)~/code/rust/ed25519-dalek ∴ cargo bench --no-default-features --features "std 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Ⓐwintermute:(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 nightly feature will enable u128/i128 features there, resulting in potentially faster performance.

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.


ed25519-dalek and our elliptic curve library (which this code uses) have received one formal cryptographic and security review. Neither have yet received what we would consider sufficient peer review by other qualified cryptographers to be considered in any way, shape, or form, safe.


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 Cargo.toml:

version = "^0.7"

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:

version = "^0.7"
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 to the Cargo.toml:

nightly = ["ed25519-dalek/nightly"]

To enable serde support, build ed25519-dalek with:

version = "^0.7"
features = ["serde"]

By default, ed25519-dalek builds against curve25519-dalek's u64_backend feature, which uses Rust's i128 feature to achieve roughly double the speed as the 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 experimental avx2_backend. To use it, compile with RUSTFLAGS="-C target_cpu=native" cargo build --no-default-features --features="avx2_backend"


  • Batch signature verification, maybe?
  • We can probably make this go even faster if we implement SHA512, rather than using the rust-crypto implementation whose API requires that we allocate memory and bzero it before mutating to store the digest.
  • Incorporate ed25519-dalek into Brian Smith's crypto-bench.