encryption.js

const bip39 = require('bip39');
const {hdkey} = require('ethereumjs-wallet');
const {createCipheriv, createDecipheriv} = require('crypto');

const encodeSecret = (mnemonic, id, secret, encoding) => {
  const wallet = hdkey.fromMasterSeed(bip39.mnemonicToSeedSync(mnemonic)).derivePath(`m/44'/60'/0'/0/0`).getWallet();
  const privateKey = wallet.privateKey;

  const key = privateKey.slice(0, 24);
  // const aad = Buffer.from('0123456789', 'hex');

  const nonce = Buffer.alloc(12);
  const dataView = new DataView(nonce.buffer);
  dataView.setUint32(0, id);
  const cipher = createCipheriv('aes-192-ccm', key, nonce, {
    authTagLength: 16,
  });
  /* cipher.setAAD(aad, {
    plaintextLength: Buffer.byteLength(secret)
  }); */
  const ciphertext = cipher.update(secret, encoding);
  cipher.final();
  const tag = cipher.getAuthTag();
  return {
    ciphertext,
    tag,
  };
};
const decodeSecret = (mnemonic, id, {ciphertext, tag}, encoding) => {
  const wallet = hdkey.fromMasterSeed(bip39.mnemonicToSeedSync(mnemonic)).derivePath(`m/44'/60'/0'/0/0`).getWallet();
  const privateKey = wallet.privateKey;

  const key = privateKey.slice(0, 24);
  // const aad = Buffer.from('0123456789', 'hex');

  const nonce = Buffer.alloc(12);
  const dataView = new DataView(nonce.buffer);
  dataView.setUint32(0, id);
  const decipher = createDecipheriv('aes-192-ccm', key, nonce, {
    authTagLength: 16,
  });
  decipher.setAuthTag(tag);
  /* decipher.setAAD(aad, {
    plaintextLength: ciphertext.length
  }); */
  const receivedPlaintext = decipher.update(ciphertext, null, encoding);
  return receivedPlaintext;
};

module.exports = {
  encodeSecret,
  decodeSecret,
};