OpenID、OAuth、OpenID Connect的区别解释:

OpenID is a protocol for authentication while OAuth is for authorization. Authentication is about making sure that the guy you are talking to is indeed who he claims to be. Authorization is about deciding what that guy should be allowed to do. In OpenID, authentication is delegated: server A wants to authenticate user U, but U's credentials (e.g. U's name and password) are sent to another server, B, that A trusts (at least, trusts for authenticating users). Indeed, server B makes sure that U is indeed U, and then tells to A: "ok, that's the genuine U". In OAuth, authorization is delegated: entity A obtains from entity B an "access right" which A can show to server S to be granted access; B can thus deliver temporary, specific access keys to A without giving them too much power. You can imagine an OAuth server as the key master in a big hotel; he gives to employees keys which open the doors of the rooms that they are supposed to enter, but each key is limited (it does not give access to all rooms); furthermore, the keys self-destruct after a few hours. To some extent, authorization can be abused into some pseudo-authentication, on the basis that if entity A obtains from B an access key through OAuth, and shows it to server S, then server S may infer that B authenticated A before granting the access key. So some people use OAuth where they should be using OpenID. This schema may or may not be enlightening; but I think this pseudo-authentication is more confusing than anything. OpenID Connect does just that: it abuses OAuth into an authentication protocol. In the hotel analogy: if I encounter a purported employee and that person shows me that he has a key which opens my room, then I suppose that this is a true employee, on the basis that the key master would not have given him a key which opens my room if he was not.

(源)

OpenID Connect与OpenID 2.0有何不同? OpenID Connect执行许多与OpenID 2.0相同的任务，但确实如此 以一种api友好的方式，在本地和移动设备上都可用 应用程序。OpenID Connect为健壮性定义了可选机制 签名和加密。而OAuth 1.0a和OpenID的集成 2.0需要一个扩展，在OpenID连接中，OAuth 2.0功能与协议本身集成。

(源)

OpenID connect will give you an access token plus an id token. The id token is a JWT and contains information about the authenticated user. It is signed by the identity provider and can be read and verified without accessing the identity provider. In addition, OpenID connect standardizes quite a couple things that oauth2 leaves up to choice. for instance scopes, endpoint discovery, and dynamic registration of clients. This makes it easier to write code that lets the user choose between multiple identity providers.

(源)

谷歌是2.0版的

谷歌的OAuth 2.0 api可用于身份验证和 授权。本文档描述了我们的OAuth 2.0实现 用于身份验证，符合OpenID Connect 规范，并且是OpenID认证。在 “OAuth 2.0访问谷歌接口”也适用于本业务。如果 如果您想以交互方式探索此协议，我们推荐 谷歌OAuth 2.0游乐场。

(源)

OpenID(主要)用于识别/身份验证，这样stackoverflow.com就知道我拥有chris.boyle.name(或任何位置)，因此我可能就是昨天拥有chris.boyle.name并获得一些声誉点的同一个人。

OAuth是为授权代表您执行操作而设计的，因此stackoverflow.com(或任何地方)可以请求许可，例如，自动代表您发送Tweet，而不需要知道您的Twitter密码。

OpenID和OAuth都是用于身份验证和/或授权的基于http的协议。两者都旨在允许用户执行操作，而无需向客户端或第三方提供身份验证凭据或全面权限。虽然它们是相似的，并且有建议将它们一起使用的标准，但它们是单独的协议。

OpenID用于联合身份验证。客户机接受来自任何提供者的身份断言(尽管客户机可以自由地将提供者列入白名单或黑名单)。

OAuth用于委托授权。客户端向提供者注册，提供者提供授权令牌，客户端接受这些授权令牌以代表用户执行操作。

OAuth目前更适合于授权，因为身份验证后的进一步交互被内置到协议中，但这两个协议都在不断发展。OpenID及其扩展可用于授权，OAuth可用于身份验证，可以将其视为无操作授权。

我相信重新审视这个问题是有意义的，正如评论中所指出的，OpenID Connect的引入可能带来更多的困惑。

OpenID Connect是一种类似于OpenID 1.0/2.0的身份验证协议，但它实际上构建在OAuth 2.0之上，因此您将获得授权功能和身份验证功能。这两者之间的区别在这篇(相对较新的，但很重要的)文章中有很好的详细解释:http://oauth.net/articles/authentication/

创建这两个协议的原因不同。创建OAuth是为了授权第三方访问资源。创建OpenID是为了执行分散的身份验证。本网站说明如下:

OAuth是一种用于验证终端用户身份并向第三方授予权限的协议。这个验证的结果是一个令牌。第三方可以使用这个令牌来代表用户访问资源。令牌有一个作用域。作用域用于验证用户是否可以访问某个资源

OpenID是用于分散身份验证的协议。认证是关于身份的;确定用户实际上就是他所声称的那个人。去中心化意味着该服务不知道需要保护的任何资源或应用程序的存在。这就是OAuth和OpenID之间的关键区别。

有三种方法可以比较OAuth和OpenID:

1. 目的

OpenID是为联邦身份验证而创建的，也就是说，允许第三方使用用户已经拥有的帐户为您验证用户身份。联合这个术语在这里非常重要，因为OpenID的全部意义在于可以使用任何提供者(白名单除外)。你不需要预先选择或与提供商协商协议，以允许用户使用他们拥有的任何其他帐户。

OAuth的创建是为了消除用户与第三方应用程序共享密码的需要。它实际上是作为解决OpenID问题的一种方式开始的:如果您在站点上支持OpenID，则不能使用HTTP基本凭据(用户名和密码)来提供API，因为用户在站点上没有密码。

The problem is with this separation of OpenID for authentication and OAuth for authorization is that both protocols can accomplish many of the same things. They each provide a different set of features which are desired by different implementations but essentially, they are pretty interchangeable. At their core, both protocols are an assertion verification method (OpenID is limited to the 'this is who I am' assertion, while OAuth provides an 'access token' that can be exchanged for any supported assertion via an API).

2. 特性

这两种协议都为站点提供了一种方法，可以将用户重定向到其他地方，然后返回一个可验证的断言。OpenID提供身份断言，而OAuth以访问令牌的形式更为通用，可用于“向OAuth提供者询问问题”。但是，它们各自支持不同的特性:

OpenID - the most important feature of OpenID is its discovery process. OpenID does not require hard coding each the providers you want to use ahead of time. Using discovery, the user can choose any third-party provider they want to authenticate. This discovery feature has also caused most of OpenID's problems because the way it is implemented is by using HTTP URIs as identifiers which most web users just don't get. Other features OpenID has is its support for ad-hoc client registration using a DH exchange, immediate mode for optimized end-user experience, and a way to verify assertions without making another round-trip to the provider.

OAuth - the most important feature of OAuth is the access token which provides a long lasting method of making additional requests. Unlike OpenID, OAuth does not end with authentication but provides an access token to gain access to additional resources provided by the same third-party service. However, since OAuth does not support discovery, it requires pre-selecting and hard-coding the providers you decide to use. A user visiting your site cannot use any identifier, only those pre-selected by you. Also, OAuth does not have a concept of identity so using it for login means either adding a custom parameter (as done by Twitter) or making another API call to get the currently "logged in" user.

3.技术的实现

这两种协议在使用重定向获取用户授权方面具有共同的架构。在OAuth中，用户授权访问他们受保护的资源，在OpenID中，用户授权访问他们的身份。但这就是他们所有的共同点。

每个协议都有不同的方法来计算用于验证请求或响应的真实性的签名，并且每个协议都有不同的注册要求。