1.4. 访问令牌 （1.4. Access Token）

1.4. 访问令牌

访问令牌是用于访问受保护资源的凭据。访问令牌是一个代表向客户端颁发的授权的字符串。该字符串通常对于客户端是不透明的。令牌代表了访问权限的由资源所有者许可并由资源服务器和授权服务器实施的具体范围和期限。

令牌可以表示一个用于检索授权信息的标识符或者可以以可验证的方式自包含授权信息（即令牌字符串由数据和签名组成）。额外的身份验证凭据——在本规范范围以外——可以被要求以便客户端使用令牌。

访问令牌提供了一个抽象层，用单一的资源服务器所能够理解的令牌，代替不同的授权结构（例如，用户名和密码）。这种抽象使得颁发访问令牌比颁发用于获取令牌的授权许可更受限制，同时消除了资源服务器理解各种各样身份认证方法的需要。

基于资源服务器的安全要求访问令牌可以有不同的格式、结构及采用的方法（如，加密属性）。访问令牌的属性和用于访问受保护资源的方法超出了本规范的范围，它们在RFC6750等配套规范中定义。

 

1.4. Access Token

   Access tokens are credentials used to access protected resources.  An
   access token is a string representing an authorization issued to the
   client.  The string is usually opaque to the client.  Tokens
   represent specific scopes and durations of access, granted by the
   resource owner, and enforced by the resource server and authorization
   server.

   The token may denote an identifier used to retrieve the authorization
   information or may self-contain the authorization information in a
   verifiable manner (i.e., a token string consisting of some data and a
   signature).  Additional authentication credentials, which are beyond
   the scope of this specification, may be required in order for the
   client to use a token.

   The access token provides an abstraction layer, replacing different
   authorization constructs (e.g., username and password) with a single
   token understood by the resource server.  This abstraction enables
   issuing access tokens more restrictive than the authorization grant
   used to obtain them, as well as removing the resource server's need
   to understand a wide range of authentication methods.

   Access tokens can have different formats, structures, and methods of
   utilization (e.g., cryptographic properties) based on the resource
   server security requirements.  Access token attributes and the
   methods used to access protected resources are beyond the scope of
   this specification and are defined by companion specifications such
   as [RFC6750].