SHA256 · Hex加密
使用插件：jsHashes https://github.com/h2non/jshashes
// require the module
var Hashes = require('jshashes')
// new SHA1 instance and base64 string encoding
var SHA256 = new Hashes.SHA256().hex_hmac(key, str)
// output to console
console.log('SHA256: ' + SHA256)
