A lightweight and fast ECDSA implementation

Overview

This is a JS fork of ecdsa-python

It is compatible with OpenSSL and is fast. It uses some elegant math as Jacobian Coordinates to speed up the ECDSA.

Curves

We currently support secp256k1, but it's super easy to add more curves to the project. Just add them on curve.js

Sample Code

How to sign a json message for Stark Bank:

var ellipticcurve = require("@starkbank/ecdsa-node")
var Ecdsa = ellipticcurve.Ecdsa
var PrivateKey = ellipticcurve.PrivateKey

// Generate privateKey from PEM string
var privateKey = PrivateKey.fromPem("-----BEGIN EC PARAMETERS-----\nBgUrgQQACg==\n-----END EC PARAMETERS-----\n-----BEGIN EC PRIVATE KEY-----\nMHQCAQEEIODvZuS34wFbt0X53+P5EnSj6tMjfVK01dD1dgDH02RzoAcGBSuBBAAK\noUQDQgAE/nvHu/SQQaos9TUljQsUuKI15Zr5SabPrbwtbfT/408rkVVzq8vAisbB\nRmpeRREXj5aog/Mq8RrdYy75W9q/Ig==\n-----END EC PRIVATE KEY-----\n")

// Create message from json
let message = JSON.stringify({
    "transfers": [
        {
            "amount": 100000000,
            "taxId": "594.739.480-42",
            "name": "Daenerys Targaryen Stormborn",
            "bankCode": "341",
            "branchCode": "2201",
            "accountNumber": "76543-8",
            "tags": ["daenerys", "targaryen", "transfer-1-external-id"]
        }
    ]
})

signature = Ecdsa.sign(message, privateKey)

// Generate Signature in base64. This result can be sent to Stark Bank in header as Digital-Signature parameter
console.log(signature.toBase64())

// To double check if message matches the signature
let publicKey = privateKey.publicKey()

console.log(Ecdsa.verify(message, signature, publicKey))

Simple use:

var ellipticcurve = require("@starkbank/ecdsa-node")
var Ecdsa = ellipticcurve.Ecdsa
var PrivateKey = ellipticcurve.PrivateKey

// Generate new Keys
let privateKey = new PrivateKey()
let publicKey = privateKey.publicKey()

let message = "My test message"

// Generate Signature
let signature = Ecdsa.sign(message, privateKey)

// Verify if signature is valid
console.log(Ecdsa.verify(message, signature, publicKey))

OpenSSL

This library is compatible with OpenSSL, so you can use it to generate keys:

openssl ecparam -name secp256k1 -genkey -out privateKey.pem
openssl ec -in privateKey.pem -pubout -out publicKey.pem

Create a message.txt file and sign it:

openssl dgst -sha256 -sign privateKey.pem -out signatureDer.txt message.txt

It's time to verify:

var ellipticcurve = require("@starkbank/ecdsa-node")
var Ecdsa = ellipticcurve.Ecdsa
var Signature = ellipticcurve.Signature
var PublicKey = ellipticcurve.PublicKey
var File = ellipticcurve.utils.File

let publicKeyPem = File.read("publicKey.pem")
let signatureDer = File.read("signatureDer.txt", "binary")
let message = File.read("message.txt")

let publicKey = PublicKey.fromPem(publicKeyPem)
let signature = Signature.fromDer(signatureDer)

console.log(Ecdsa.verify(message, signature, publicKey))

You can also verify it on terminal:

openssl dgst -sha256 -verify publicKey.pem -signature signatureDer.txt message.txt

NOTE: If you want to create a Digital Signature to use in the Stark Bank, you need to convert the binary signature to base64.

openssl base64 -in signatureDer.txt -out signatureBase64.txt

With this library, you can do it:

var ellipticcurve = require("@starkbank/ecdsa-node")
var Signature = ellipticcurve.Signature
var File = ellipticcurve.utils.File

let signatureDer = File.read("signatureDer.txt", "binary")

let signature = Signature.fromDer(signatureDer)

console.log(signature.toBase64())

How to install

npm install @starkbank/ecdsa-node

Run all unit tests

Run tests in Mocha framework

node test