ecies-ed25519-morus

Experimental ECIES on Twisted Edwards Curve25519 and MORUS-1280-128

Notes

• Flexible Symmetric Cryptography - Impractical plaintext recovery attack.
• This work misuses the sign & verify keypair in the ed25519 scheme for accomplishing ECIES. We call this, a perversion because we should only use the ephemeral ones (except for the recipient).
• No security audits, and perhaps will not happen.

Example

use rand_core::RngCore;
use ecies_ed25519_morus::{encrypt_into, decrypt_into};

const BUFFER_SIZE: usize = 512 * 1024; // avoid higher than this to prevent stackoverflow
let mut rng = rand_core::OsRng::default();
let sender_keypair = ed25519_dalek::SigningKey::generate(&mut rng);
let receiver_keypair = ed25519_dalek::SigningKey::generate(&mut rng);
let sender_public = sender_keypair.verifying_key();
let receiver_public = receiver_keypair.verifying_key();
let mut random_message = [0u8; BUFFER_SIZE];
let mut decrypted_message = [0u8; BUFFER_SIZE];
let mut ciphertext = [0u8; BUFFER_SIZE];
rng.fill_bytes(&mut random_message);

let decrypt_materials = encrypt_into(
    &mut rng,
    &sender_keypair,
    &receiver_public,
    &[],
    &random_message[..],
    &mut ciphertext[..],
)
.unwrap();
decrypt_into(
    &decrypt_materials,
    &receiver_keypair,
    &sender_public,
    &[],
    &ciphertext[..],
    &mut decrypted_message[..],
)
.unwrap();

assert_eq!(random_message, decrypted_message);
assert_ne!(sender_public, receiver_public);

Features

• no-std environment (for example: wasm):

cargo add ecies-ed25519-morus --no-default-features --features="pure"

• std environment (default):

cargo add ecies-ed25519-morus

• std and aarch64 environment (for example: Apple Silicon)

cargo add ecies-ed25519-morus --features="aarch64-optimizations"

Inspirations

This work is heavily inspired by:

• ecies-ed25519, which uses AES-GCM and ephemeral keypairs (see: notes)
• rust-morus, modified for pure no-std (see: these lines)

Future Works

• Encrypt & Decrypt with associated data
• Improve tests with fuzzers & harnesses
• Add benchmark information
• Add example and diagrams to elaborate use cases
• Implement python and c/c++ wrappers