https://blog.csdn.net/chen55bo/article/details/78872555
https://www.cnblogs.com/liudw-0215/p/9927470.html
单向认证与双向认证
https://www.cnblogs.com/sunzhao/p/9081272.html
https://www.cnblogs.com/bluestorm/p/10571989.html
MD5
https://blog.csdn.net/Deft_MKJing/article/details/78287782