SHIRO 基本概念

 SHIRO 概念

// 官方術語  請多花時間理解  不限於shiro 任何技術都是如此  值得不少人學習

Apache Shiro Terminology

Please just take 2 minutes to read and understand this - it is really important

Authentication

認證，告訴系統 當前操做人是那個 / 系統進行驗證 你給的信息

Authorization

訪問控制  決定當前操做人是否有權限訪問某個資源

Cipher
A cipher is an algorithm for performing encryption or decryption. The algorithm generally relies on a piece of information called a key. And the encryption varies based on the key so decyrption is extremely difficult without it. 

Ciphers come in different variations. Block Ciphers work on blocks of symbols usually of a fixed size while Stream Ciphers work on a continuous stream of symbols. Symmetric Ciphers use the same key for encryption and decryption while Asymmetric Ciphers use different keys. And if a key in an asymmetric cipher cannot be derived from the other, then one can be shared publicly creating public/private key pairs. 

Credential
A Credential is a piece of information that verifies the identity of a user/Subject. One (or more) credentials are submitted along with Principal(s) during an authentication attempt to verify that the user/Subject submitting them is actually the associated user. Credentials are usually very secret things that only a particular user/Subject would know, such as a password or a PGP key or biometric attribute or similar mechanism. 

The idea is that for a principal, only one person would know the correct credential to 'pair' with that principal. If the current user/Subject provides the correct credential matching the one stored in the system, then the system can assume and trust that the current user/Subject is really who they say they are. The degree of trust increases with more secure credential types (e.g. biometric signature > password). 

Cryptography
Cryptography is the practice of protecting information from undesired access by hiding it or converting it into nonsense so know one else can read it. Shiro focuses on two core elements of Cryptography: ciphers that encrypt data like email using a public or private key, and hashes (aka message digests) that irreversibly encrypt data like passwords.

Hash
A Hash function is a one-way, irreversible conversion of an input source, sometimes called the message, into an encoded hash value, sometimes called the message digest. It is often used for passwords, digital fingerprints, or data with an underlying byte array. 

Permission
A Permission, at least as Shiro interprets it, is a statement that describes raw functionality in an application and nothing more. Permissions are the lowest-level constructs in security policies. They define only "What" the application can do. They do not describe "Who" is able to perform the actions. A Permission is only a statement of behavior, nothing more. 

在個人理解:權限設計裏面的最小單元  

Principal
A Principal is any identifying attribute of an application user (Subject). An 'identifying attribute' can be anything that makes sense to your application - a username, a surname, a given name, a social security number, a user ID, etc. That's it - nothing crazy. 

Shiro also references something we call a Subject's primary principal. A Primary principal is any principal that uniquely identifies theSubject across the entire application. Ideal primary principals are things like a username or a user ID that is a RDBMS user table primary key. There is only one primary principal for users (Subjects) in an application. 

當前驗證用戶的惟一標示符

Realm
A Realm is a component that can access application-specific security data such as users, roles, and permissions. It can be thought of as a security-specific DAO (Data Access Object). The Realm translates this application-specific data into a format that Shiro understands so Shiro can in turn provide a single easy-to-understand Subject programming API no matter how many data sources exist or how application-specific your data might be. 

Realms usually have a 1-to-1 correlation with a data source such as a relational database, LDAP directory, file system, or other similar resource. As such, implementations of the Realm interface use data source-specific APIs to discover authorization data (roles, permissions, etc), such as JDBC, File IO, Hibernate or JPA, or any other Data Access API. 

和數據源1對1 

Role

在權限設計裏面  我理解爲 Permission的包, 注意：系統中 並不是只有權限纔有role定義

Session

直接理解爲 可用於非WEB 環境中 httpSession

Subject

It is basically a representation of any entity that is doing something with the application. 

OOP 抽象  子應用 ？ 線程 ？ 用戶 ？ 隨意劃分