Nodejs encryption and decryption for ccavenue (aes-128-cbc)

ccavenue-encrypt-decrypt.txt

var crypto = require('crypto');

exports.encrypt = function (plainText, working_key) {
  const m = crypto.createHash('md5');
  m.update(working_key);
  const key = m.digest();
  const iv = '\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f';
  const cipher = crypto.createCipheriv('aes-128-cbc', key, iv);
  let encoded = cipher.update(plainText, 'utf8', 'hex');
  encoded += cipher.final('hex');
  return encoded;
};

exports.decrypt = function (encText, working_key) {
  const m = createHash('md5');
  m.update(working_key);
  const key = m.digest();
  const iv = '\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f';
  const decipher = createDecipheriv('aes-128-cbc', key, iv);
  let decoded = decipher.update(encText, 'hex', 'utf8');
  decoded += decipher.final('utf8');
  return decoded;
};