@starkbank/ecdsa

A lightweight and fast ECDSA implementation

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This is a pure JS implementation of the Elliptic Curve Digital Signature Algorithm. It is compatible with OpenSSL and uses elegant math such as Jacobian Coordinates to speed up the ECDSA on pure JS.

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To install StarkBanks ECDSA for Node JS, run:

`sh
npm install @starkbank/ecdsa
`

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

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We ran a test on Node 13.1.0 on a MAC Pro i5 2019. The libraries ran 100 times and showed the average times displayed bellow:

| Library | sign | verify |
| ------------------ |:-------------:| -------:|
| [crypto] | 0.5ms | 1.0ms |
| starkbank-ecdsa | 6.3ms | 15.0ms |

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How to sign a json message for [Stark Bank]:

`js
var ellipticcurve = require("@starkbank/ecdsa");
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:

`js
var ellipticcurve = require("@starkbank/ecdsa");
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));
`

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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
`

To verify, do this:

`js
var ellipticcurve = require("@starkbank/ecdsa");
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
`

You can do the same with this library:

`js
var ellipticcurve = require("@starkbank/ecdsa");
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());
`

[Stark Bank]: https://starkbank.com

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`sh
node test
`

or

`sh
./node_modules/mocha/bin/mocha
``

[Mocha framework]: https://mochajs.org/#getting-started
[crypto]: https://nodejs.org/api/crypto.html
[ecdsa]: https://www.npmjs.com/package/ecdsa