Difference between authentication, authorization,verification, validation
verification, validation, authentication, authorization 这几个术语很常用，也经常被误用，这里做一次对比总结。
identity
A security principal (you or a computer, typically) wants to access a system. Because the system doesn’t know you yet, you need to make a declaration of who you are. Your answer to the question “Who are you” is the first thing you present to a system when you want to use it. Some common examples of identity are user IDs, digital certificates (which include public keys), and ATM cards.