Heartsuit's Simple Blog
A place to hold mainly reading notes, and some technical stuff occasionally. 这里主要是一些读书笔记、感悟；还有部分技术相关的内容。
Project maintained by heartsuit Hosted on GitHub Pages — Theme by mattgraham
使用bcryptjs对密码加密时，其校验原理是怎样的？
发布：2017-08-09 Wednesday
标签：Node.js
目录[-]
Question
刚开始接触这种加密方式，而又对加密原理不了解时，很容易产生这种疑问❔：
对一个密码，bcryptjs每次生成的hash都不一样，那么它是如何进行校验的？
Basic verification
- 虽然对同一个密码，每次生成的hash不一样，但是hash中包含了salt（hash产生过程：先随机生成salt，salt跟password进行hash）；
- 在下次校验时，从hash中取出salt，salt跟password进行hash；得到的结果跟保存在DB中的hash进行比对，compareSync中已经实现了这一过程：
bcrypt.compareSync(password, hashFromDB);
Let Code tell you
const bcrypt = require('bcryptjs');
const password = "123";
// Step1: Generate Hash
// salt is different everytime, and so is hash
let salt = bcrypt.genSaltSync(10);// 10 is by default
console.log(salt);//$2a$10$TnJ1bdJ3JIzGZC/jVS.v3e
let hash = bcrypt.hashSync(password, salt); // salt is inclued in generated hash
console.log(hash);//$2a$10$TnJ1bdJ3JIzGZC/jVS.v3eXlr3ns0hDxeRtlia0CPQfLJVaRCWJVS
// Step2: Verify Password
// when verify the password, get the salt from hash, and hashed again with password
let saltFromHash = hash.substr(0, 29);
console.log(saltFromHash);//$2a$10$TnJ1bdJ3JIzGZC/jVS.v3e
let newHash = bcrypt.hashSync(password, saltFromHash);
console.log(newHash);//$2a$10$TnJ1bdJ3JIzGZC/jVS.v3eXlr3ns0hDxeRtlia0CPQfLJVaRCWJVS
console.log(hash === newHash); //true
// back end compare
console.log(bcrypt.compareSync(password, hash)); //true
If you have any questions or any bugs are found, please feel free to contact me.
Your comments and suggestions are welcome!
「说点什么吧😊~~😊」：
