eth-crypto/src/public-key.js

Cryptographic functions for ethereum and how to use them with web3 and solidity

import {
    secp256k1
} from 'ethereum-cryptography/secp256k1';
import {
    pubToAddress,
    toChecksumAddress,
    hexToBytes,
    bytesToHex
} from '@ethereumjs/util';
import {
    hexToUnit8Array,
    uint8ArrayToHex,
    addLeading0x
} from './util';

export function compress(startsWith04) {

    // add trailing 04 if not done before
    const testBuffer = Buffer.from(startsWith04, 'hex');
    if (testBuffer.length === 64) startsWith04 = '04' + startsWith04;


    return uint8ArrayToHex(
        secp256k1.ProjectivePoint.fromHex(hexToUnit8Array(startsWith04)).toRawBytes(true)
    );
}

export function decompress(startsWith02Or03) {

    // if already decompressed an not has trailing 04
    const testBuffer = Buffer.from(startsWith02Or03, 'hex');
    if (testBuffer.length === 64) startsWith02Or03 = '04' + startsWith02Or03;

    let decompressed = uint8ArrayToHex(
        secp256k1.ProjectivePoint.fromHex(hexToUnit8Array(startsWith02Or03)).toRawBytes(false)
    );

    // remove trailing 04
    decompressed = decompressed.substring(2);
    return decompressed;
}

/**
 * generates the ethereum-address of the publicKey
 * We create the checksum-address which is case-sensitive
 * @returns {string} address
 */
export function toAddress(publicKey) {

    // normalize key
    publicKey = decompress(publicKey);
    publicKey = addLeading0x(publicKey);

    const addressBuffer = pubToAddress(hexToBytes(publicKey));
    const address = bytesToHex(addressBuffer);

    const checkSumAdress = toChecksumAddress(addLeading0x(address));
    return checkSumAdress;
}