eth-crypto/src/cipher.js

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

import {
    compress,
    decompress
} from './public-key';

export function stringify(cipher) {
    if (typeof cipher === 'string') return cipher;

    // use compressed key because it's smaller
    const compressedKey = compress(cipher.ephemPublicKey);

    const ret = Buffer.concat([
        Buffer.from(cipher.iv, 'hex'), // 16bit
        Buffer.from(compressedKey, 'hex'), // 33bit
        Buffer.from(cipher.mac, 'hex'), // 32bit
        Buffer.from(cipher.ciphertext, 'hex') // var bit
    ]);

    return ret.toString('hex');


}

export function parse(str) {
    if (typeof str !== 'string')
        return str;

    const buf = Buffer.from(str, 'hex');

    const ret = {
        iv: buf.toString('hex', 0, 16),
        ephemPublicKey: buf.toString('hex', 16, 49),
        mac: buf.toString('hex', 49, 81),
        ciphertext: buf.toString('hex', 81, buf.length)
    };

    // decompress publicKey
    ret.ephemPublicKey = '04' + decompress(ret.ephemPublicKey);

    return ret;
}