Crate ed25519

Ed25519 signatures.

Edwards Digital Signature Algorithm (EdDSA) over Curve25519 as specified in RFC 8032: https://tools.ietf.org/html/rfc8032

This crate doesn't contain an implementation of Ed25519, but instead contains an ed25519::Signature type which other crates can use in conjunction with the signature::Signer and signature::Verifier traits defined in the signature crate.

These traits allow crates which produce and consume Ed25519 signatures to be written abstractly in such a way that different signer/verifier providers can be plugged in, enabling support for using different Ed25519 implementations, including HSMs or Cloud KMS services.

Minimum Supported Rust Version

Rust 1.40 or higher.

Minimum supported Rust version may be changed in the future, but such changes will be accompanied with a minor version bump.

Using Ed25519 generically over algorithm implementations/providers

By using the ed25519 crate, you can write code which signs and verifies messages using the Ed25519 signature algorithm generically over any supported underlying Ed25519 implementation (see the next section for available providers).

This allows consumers of your code to plug in whatever implementation they want to use without having to add all potential Ed25519 libraries you'd like to support as optional dependencies.

Below is a usage example of how to use this crate to do so:

use ed25519::signature::{Signer, Verifier};

pub struct HelloSigner<S> {
    pub signer: S
}

impl<S> HelloSigner<S>
where
    S: Signer<ed25519::Signature>
{
    pub fn sign(&self, person: &str) -> ed25519::Signature {
        // NOTE: use `try_sign` if you'd like to be able to handle
        // errors from external signing services/devices (e.g. HSM/KMS)
        // <https://docs.rs/signature/latest/signature/trait.Signer.html#tymethod.try_sign>
        self.signer.sign(format_message(person).as_bytes())
    }
}

pub struct HelloVerifier<V> {
    pub verifier: V
}

impl<V> HelloVerifier<V>
where
    V: Verifier<ed25519::Signature>
{
    pub fn verify(
        &self,
        person: &str,
        signature: &ed25519::Signature
    ) -> Result<(), ed25519::Error> {
        self.verifier.verify(format_message(person).as_bytes(), signature)
    }
}

fn format_message(person: &str) -> String {
    format!("Hello, {}!", person)
}

A hypothetical consumer of the above code can then instantiate HelloSigner using ed25519-dalek (via the signatory-dalek crate) as:

use signatory_dalek::Ed25519Signer;
use hello_signer::HelloSigner; // i.e. `HelloSigner` defined in the above example

/// `HelloSigner` instantiated with an `ed25519-dalek` signature provider
pub type DalekHelloSigner = HelloSigner<Ed25519Signer>;

Available Ed25519 providers

The following libraries natively support the types and traits from the ed25519 crate:

• yubihsm - host-side client library for YubiHSM2 devices from Yubico

The Signatory project provides wrappers for several notable crates which produce or verify Ed25519 signatures:

• signatory-dalek - wrapper for ed25519-dalek
• signatory-ring - wrapper for ring
• signatory-sodiumoxide - wrapper for sodiumoxide

Re-exports

pub use signature;

Structs

Error	Signature errors.
Signature	Ed25519 signature.

Constants

SIGNATURE_LENGTH

Length of an Ed25519 signature