const SM4 = require('gm-crypt').sm4

let sm4Config = {
  // encrypt/decypt main key; cannot be omitted
  key: 'JeF8U9wHFOMfs2Y8',

  // optional; can be 'cbc' or 'ecb'
  mode: 'cbc', // default

  // optional; when use cbc mode, it's �necessary
  iv: 'UISwD9fW6cFh9SNS', // default is null

  // optional: this is the cipher data's type; Can be 'base64' or 'text'
  cipherType: 'base64' // default is base64
}

let sm4 = new SM4(sm4Config)

let plaintext = '**国密加解密算法'
let ciphertext = sm4.encrypt(plaintext)
// ciphertext's result is 'j/+HgSpv8RZQI2YtSq0L1RnemiSokMm1VvLHSTt245U='

let ciphertext = 'j/+HgSpv8RZQI2YtSq0L1RnemiSokMm1VvLHSTt245U='
let plaintext = sm4.decrypt(ciphertext)
// plaintext's result is '**国密加解密算法'