Curve25519 signatures like in the early Axolotl

Rust

Import

use ed25519_axolotl::{
    fast_signature,
    full_signature,
    decode_message,
    random_bytes,
    str_to_vec32,
    vec32_to_str,
    KeyPair
    verify,
};

Generate New KeyPair

• the seed needs 32 bytes length or more
• if none, generate random keys

// seed: Vec<u32>
// let keys = KeyPair::new(Some(seed));

let keys = KeyPair::new(None);

println!("{}", keys);

Fast Signature

• 64 byte signature
• quick to sign and verify
• don't possible to decode signature back to message

let keys = KeyPair::new(None);

let msg = str_to_vec32("hello e25519 axolotl".to_string());
let signature = fast_signature(
    keys.prvk,
    msg.clone(),
    Some(random_bytes(64))
);

Full Signature

• (64 + message length) byte signature
• slow to sign and verify
• it is possible to decode the signature back to the message

let keys = KeyPair::new(None);

let msg = str_to_vec32("hello e25519 axolotl".to_string());
let signature = full_signature(
    keys.prvk,
    msg.clone(),
    Some(random_bytes(64))
);

Validate Signatures

• works with both fast and full signatures

let keys = KeyPair::new(None);


let msg = str_to_vec32("hello e25519 axolotl".to_string());
let signature_full = full_signature(
    keys.prvk,
    msg.clone(),
    Some(random_bytes(64))
);
assert_eq!(true, validate_signature(keys.pubk, msg, signature_full));

let signature_fast = fast_signature(
    keys.prvk,
    msg.clone(),
    Some(random_bytes(64))
);
assert_eq!(true, validate_signature(keys.pubk, msg, signature_fast));

Decode Message

• possible only for full_signature function

let keys = KeyPair::new(None);

let msg = str_to_vec32("hello e25519 axolotl".to_string());
let mut sign_msg = full_signature(
    keys.prvk,
    msg.clone(),
    Some(random_bytes(64))
);
let decoded_msg = decode_message(keys.pubk, &mut sign_msg);

NodeJs (WebAssembly)

Import

import * as wasm from "ed25519_axolotl";

or

const wasm = require("ed25519_axolotl")

Generate New KeyPair

• the seed needs 32 bytes length or more
• if none, generate random keys

// const seed =  wasm.stringToUint32Array("your seed with 32 bytes of length or more")
// const keys = new wasm.KeyPair(seed)
const keys = new wasm.KeyPair()

Fast Signature

• 64 byte signature
• quick to sign and verify
• don't possible to decode signature back to message

const keys = new wasm.KeyPair()

const msg = wasm.stringToUint32Array("hello lunes")
const signature = wasm.fastSignature(k.privateKey, msg, wasm.randomBytes(64))

Full Signature

• (64 + message length) byte signature
• slow to sign and verify
• it is possible to decode the signature back to the message

const keys = new wasm.KeyPair()

const msg = wasm.stringToUint32Array("hello lunes")
const signature = wasm.fullSignature(k.privateKey, msg, wasm.randomBytes(64))

Validate Signatures

• works with both fast and full signatures

const keys = new wasm.KeyPair()
const msg = wasm.stringToUint32Array("hello lunes")

const signatureFast = wasm.fastSignature(keys.privateKey, msg, wasm.randomBytes(64))
const validated = wasm.validateSignature(keys.publicKey, msg, signatureFast)

const signatureFull = wasm.fullSignature(keys.privateKey, msg, wasm.randomBytes(64))
const validated = wasm.validateSignature(keys.publicKey, msg, signatureFull)

Decode Message

• possible only for full_signature function

const keys = new wasm.KeyPair()
const msg = wasm.stringToUint32Array("hello lunes")
const signature = wasm.fullSignature(keys.privateKey, msg, wasm.randomBytes(64))

const dmsg = wasm.uint32ArrayToString(
    wasm.decode_message(keys.publiKey, signature)
)

Python (Cython)

Import

from ed25519_axolotl import KeyPair
from ed25519_axolotl import (
    validate_signature,
    fast_signature,
    full_signature,
    decode_message
)

Generate New KeyPair

• the seed needs 32 bytes length or more
• if none, generate random keys

# seed: bytes = [i for i in range(32)]
# keys = KeyPair( seed )
keys = KeyPair()

keys.private_key
keys.public_key

Fast Signature

• 64 byte signature
• quick to sign and verify
• don't possible to decode signature back to message

keys = KeyPair()
message = b"hello lunes"

signature = fast_signature(keys.private_key, message, random_bytes(64))

Full Signature

• (64 + message length) byte signature
• slow to sign and verify
• it is possible to decode the signature back to the message

keys = KeyPair()
message = b"hello lunes"

signature_full = full_signature(keys.private_key, message, random_bytes(64))

Validate Signatures

• works with both fast and full signatures

keys = KeyPair()
msg = b"hello lunes"

signatureFast = fast_signature(k.private_key, msg, random_bytes(64))
validated = validate_signature(keys.public_key, msg, signature_fast)

signatureFull = fullSignature(k.private_key, msg, random_bytes(64))
validated = validate_signature(keys.public_key, msg, signature_full)

Decode Message

• possible only for full_signature function

keys = KeyPair()
message = b"hello lunes"
signature_full = full_signature(keys.private_key, message, random_bytes(64))

decode_msg = decode_message(keys.public_key, signature_full)
like_string_msg   = ''.join(map(chr, decode_msg)))
like_bytes_msg    = bytes(decode_msg)
like_list_int_msg = decode_msg

Credits

• Ported to Rust by Miguel Sandro Lucero, miguel.sandro@gmail.com, 2021.09.11, see here
• Curve25519 signatures idea and math by Trevor Perrin, see here
• Derived from axlsign.js written by Dmitry Chestnykh, see here
• You can use it under MIT.