Crate ed25519_dalek

Expand description

A Rust implementation of ed25519 key generation, signing, and verification.

Example

Creating an ed25519 signature on a message is simple.

First, we need to generate a Keypair, which includes both public and secret halves of an asymmetric key. To do so, we need a cryptographically secure pseudorandom number generator (CSPRNG). For this example, we’ll use the operating system’s builtin PRNG:

extern crate rand;
extern crate ed25519_dalek;

use rand::rngs::OsRng;
use ed25519_dalek::Keypair;
use ed25519_dalek::Signature;

let mut csprng = OsRng{};
let keypair: Keypair = Keypair::generate(&mut csprng);

We can now use this keypair to sign a message:

use ed25519_dalek::{Signature, Signer};
let message: &[u8] = b"This is a test of the tsunami alert system.";
let signature: Signature = keypair.sign(message);

As well as to verify that this is, indeed, a valid signature on that message:

use ed25519_dalek::Verifier;
assert!(keypair.verify(message, &signature).is_ok());

Anyone else, given the public half of the keypair can also easily verify this signature:

use ed25519_dalek::{PublicKey, Verifier};

let public_key: PublicKey = keypair.public;
assert!(public_key.verify(message, &signature).is_ok());

Serialisation

PublicKeys, SecretKeys, Keypairs, and Signatures can be serialised into byte-arrays by calling .to_bytes(). It’s perfectly acceptible and safe to transfer and/or store those bytes. (Of course, never transfer your secret key to anyone else, since they will only need the public key to verify your signatures!)

use ed25519_dalek::{PUBLIC_KEY_LENGTH, SECRET_KEY_LENGTH, KEYPAIR_LENGTH, SIGNATURE_LENGTH};

let public_key_bytes: [u8; PUBLIC_KEY_LENGTH] = public_key.to_bytes();
let secret_key_bytes: [u8; SECRET_KEY_LENGTH] = keypair.secret.to_bytes();
let keypair_bytes:    [u8; KEYPAIR_LENGTH]    = keypair.to_bytes();
let signature_bytes:  [u8; SIGNATURE_LENGTH]  = signature.to_bytes();

And similarly, decoded from bytes with ::from_bytes():

let public_key: PublicKey = PublicKey::from_bytes(&public_key_bytes)?;
let secret_key: SecretKey = SecretKey::from_bytes(&secret_key_bytes)?;
let keypair:    Keypair   = Keypair::from_bytes(&keypair_bytes)?;
let signature:  Signature = Signature::try_from(&signature_bytes[..])?;

Using Serde

If you prefer the bytes to be wrapped in another serialisation format, all types additionally come with built-in serde support by building ed25519-dalek via:

$ cargo build --features="serde"

They can be then serialised into any of the wire formats which serde supports. For example, using bincode:


use bincode::serialize;

let encoded_public_key: Vec<u8> = serialize(&public_key).unwrap();
let encoded_signature: Vec<u8> = serialize(&signature).unwrap();

After sending the encoded_public_key and encoded_signature, the recipient may deserialise them and verify:

use bincode::deserialize;

let message: &[u8] = b"This is a test of the tsunami alert system.";
let decoded_public_key: PublicKey = deserialize(&encoded_public_key).unwrap();
let decoded_signature: Signature = deserialize(&encoded_signature).unwrap();

let verified: bool = decoded_public_key.verify(&message, &decoded_signature).is_ok();

assert!(verified);