A lightweight and fast ECDSA implementation

Overview

This is a Ruby implementation of the Elliptic Curve Digital Signature Algorithm. It works by wrapping the built-in openSSl Ruby module.

Installation

To install StarkBank`s ECDSA-Ruby, run:

gem install starkbank-ecdsa

Speed

We ran a test on Ruby 2.6.3 on a MAC Pro i5 2019. The library ran 100 times and showed the average times displayed bellow:

Library	sign	verify
starkbank-ecdsa	0.5ms	0.4ms

Compatibility

ECDSA-Ruby uses the built-in openSSL Ruby library, which has to be linked against the system open SSL during Ruby build to work, if your ruby version is 2.3 or lower. It should work right out of the box on 2.4+, though.

Sample Code

How to sign a json message for Stark Bank:

require 'starkbank-ecdsa'
require "json"

# Generate privateKey from PEM string
privateKey = EllipticCurve::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
message = {
    "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"]
        }
    ]
}.to_json

signature = EllipticCurve::Ecdsa.sign(message, privateKey)

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

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

puts EllipticCurve::Ecdsa.verify(message, signature, publicKey)

Simple use:

require 'starkbank-ecdsa'

# Generate new Keys
privateKey = EllipticCurve::PrivateKey.new()
publicKey = privateKey.publicKey()

message = "My test message"

# Generate Signature
signature = EllipticCurve::Ecdsa.sign(message, privateKey)

# Verify if signature is valid
puts EllipticCurve::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:

require 'starkbank-ecdsa'

publicKeyPem = EllipticCurve::Utils::File.read("publicKey.pem")
signatureDer = EllipticCurve::Utils::File.read("signatureDer.txt", "binary")
message = EllipticCurve::Utils::File.read("message.txt")

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

puts 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:

require 'starkbank-ecdsa'

signatureDer = EllipticCurve::Utils::File.read("test/signatureDer.txt", "binary")

signature = EllipticCurve::Signature.fromDer(signatureDer)

puts signature.toBase64()

Run all unit tests

Run tests script

ruby test/test.rb