EC-crypto

Visual demonstration of Elliptic-curve cryptography in the command prompt.

Table of Contents

• Install
• Usage
• Showcase
• Instructions
• Supported Curves
• 3rd party libraries used

Install

Clone and install this Github repository

git clone https://github.com/johannes67890/EC-crypto.git

npm install

Usage

// Run command prompt application
> npm run cdm

// Run test of the applications functions
> npm run test

Elliptic Curve Digital Signature Algorithm

Showcase

// Create and initialize EC & signature context
const ec = new EC(secp256k1); 
const signature = new Signature(secp256k1);

// Generate key pair
const keySet = new KeySet(secp256k1);
const {privateKey, publicKey } = keySet;

// Message to sign
const message = "Hello World!";

// Sign: Hashes and signs thhe decopmressed private key to the signature function.
const signatureValue = signature.signMsg(message, ec.decompressPoint(privateKey)); 
    
// Verify: Decopmress public key to verify match of signature function.
const verify = signature.verifyMsg(message, signatureValue, ec.decompressPoint(publicKey)); 

console.log("Verify: ", verify); // Return true or false

Instructions

Types

// Holds x & y cordinats of the corresponding Point 
interface Point {
  x: BN;
  y: BN;
}

interface signature {
// Holds r & s cordinats of the corresponding signature 
  r: BN;
  s: BN;
}

Functions

Utils

• isOnCurve(Point) - Check if Point is on curve.
• isInfinity(Point) - Check if Point is Infinity
• pointToBN(Point) - Converts type Point to a BN instance
• decompressPoint(BN) - Converts BN to type Point
• concatPoint(x: BN, y: BN) - Concatenates two BN instances into type Point
• hashMsgSHA256(string) - Hashes string with SHA256

Arithmetic for Elliptic Curves

• addMod(x: BN, y: BN) - addMod computes z = (x + y) % p

• subMod(x: BN, y: BN) - subMod computes z = (x - y) % p

• mulMod(x: BN, y: BN) - mulMod computes z = (x * y) % p

• expMod(x: BN, y: BN) - expMod computes z = (x^^y) % p

  Where p is the prime order of the Elliptic curve

Efficient Implementations of Elliptic Curves

• pointAdd(Point1, Point2) - Computes the sum of two points on the elliptic curve.

• pointDouble(Point) - If two points are coincident, Computes point doubling of the point on the elliptic curve.

• pointMul(k: BN, Point) - multiplies a point by the scalar k

Digital Signatures

• signMsg(msg, privateKey, k?) - Returns a signature from a message msg, with the corresponding PrivateKey (Precomputed k is optional)
• verifyMsg(msg, signature, publicKey) - Returns True or False if the signature is valied corresponding to the publicKey and msg

Key generation

• generatePrivateKey() - Generates a BN instance of a random 32 byte size private Key.
• generatePublicKey(privateKey: BN) - Generates a BN instance of a public key from privateKey

NOTE: Generate a key pair by initializing new KeySet(curve)

example

// Generate key pair
const keySet = new KeySet(secp256k1);
const { privateKey, publicKey } = keySet;

Supported Curves

• Secp256k1

More under development

3rd party libaries used

bn.js

jest

hash.js

Back to the top