ecies-parity

This is a javaScript Elliptic curve Integrated Encryption Scheme (ECIES) library for both browserify and node.js. This implementation mimics parity's rust implementation to allow dapps to encrypt/decrypt messages from parity's extended JSON RPC API.

This module is a modified version of the eccrypto javascript library.

Motivation

Parity has implemented ECIES encryption and decryption for arbitrary messages through its extended JSON RPC API. Other Ethereum clients, (i.e. Metamask, go-ethereum) have not implemented such encryption. Dapps wishing to utilise Parity's features but also facilitate other Ethereum clients may require encrypting and decrypting Parity's messages in the browser. This package is designed to facilitate such tasks.

Implementation details

As with eccrypto, this library provides two implementations for Browser and Node.js with the same API.

The ECIES implementation details mimic those introduced by Parity, which are

• Implements a SHA256 Key Derivation Function (KDF).
• Uses ECDH based only on the secp256k1 curve (To match common blockchain transaction signing).
• AES-128-CTR based symmetric encryption (uses a 128 bit shared key derived from ECDH).

Cryptography Warning

The ECIES implementation given here is solely based off Parity's implementation. This module offers no guarantees as to the security or validity of the implementation. Furthermore, this project is being actively developed and as such should not be used for highly sensitive information.

Usage

Although this module is primarily developed for ECIES encryption/decryption extra elliptic curve functionality is given.

ECIES (Parity Encryption/Decryption)

const crypto = require("crypto");
const ecies = require("ecies-parity");

var privateKeyA = crypto.randomBytes(32);
var publicKeyA = ecies.getPublic(privateKeyA);
var privateKeyB = crypto.randomBytes(32);
var publicKeyB = ecies.getPublic(privateKeyB);

// Encrypting the message for B.
ecies.encrypt(publicKeyB, Buffer.from("msg to b")).then(function(encrypted) {
  // B decrypting the message.
  ecies.decrypt(privateKeyB, encrypted).then(function(plaintext) {
    console.log("Message to part B:", plaintext.toString());
  });
});

// Encrypting the message for A.
ecies.encrypt(publicKeyA, Buffer.from("msg to a")).then(function(encrypted) {
  // A decrypting the message.
  ecies.decrypt(privateKeyA, encrypted).then(function(plaintext) {
    console.log("Message to part A:", plaintext.toString());
  });
});

Signing

const crypto = require("crypto");
const ecies = require("ecies-parity");

// A new random 32-byte private key.
var privateKey = crypto.randomBytes(32);
// Corresponding uncompressed (65-byte) public key.
var publicKey = ecies.getPublic(privateKey);

var str = "message to sign";
// Always hash you message to sign!
var msg = crypto.createHash("sha256").update(str).digest();

ecies.sign(privateKey, msg).then(function(sig) {
  console.log("Signature in DER format:", sig);
  ecies.verify(publicKey, msg, sig).then(function() {
    console.log("Signature is OK");
  }).catch(function() {
    console.log("Signature is BAD");
  });
});

ECDH

const crypto = require("crypto");
const ecies = require("ecies-parity");

var privateKeyA = crypto.randomBytes(32);
var publicKeyA = ecies.getPublic(privateKeyA);
var privateKeyB = crypto.randomBytes(32);
var publicKeyB = ecies.getPublic(privateKeyB);

ecies.derive(privateKeyA, publicKeyB).then(function(sharedKey1) {
  ecies.derive(privateKeyB, publicKeyA).then(function(sharedKey2) {
    console.log("Both shared keys are equal:", sharedKey1, sharedKey2);
  });
});