[Bot Framework SDK]使用Bot连接器API进行身份验证

您的机器人通过安全通道（SSL/TLS）使用HTTP与机器人连接器服务通信。当你的机器人向连接器服务发送请求时，它必须包含连接器服务可以用来验证其身份的信息。同样，当连接器服务向您的机器人发送请求时，它必须包含机器人可以用来验证其身份的信息。本文描述了在机器人和机器人连接器服务之间进行的服务级别身份验证的身份验证技术和要求。如果您正在编写自己的身份验证代码，则必须实现本文中描述的安全过程，以使您的机器人能够与bot Connector服务交换消息。

重要事项

如果你正在编写自己的身份验证代码，正确实施所有安全程序至关重要。通过实施本文中的所有步骤，您可以降低攻击者能够读取发送给您的机器人的消息、发送冒充您的机器人和窃取密钥的风险。

如果您使用的是Bot Framework SDK，则不需要实现本文中描述的安全过程，因为SDK会自动为您完成。只需使用您在注册过程中为机器人获得的应用程序ID和密码配置您的项目，SDK将处理其余部分。

Four authentication technologies are used to establish trust between a bot and the Bot Connector:

This article describes how to use these technologies via standard HTTPS and JSON. No special SDKs are required, although you may find that helpers for OpenID and others

 are useful.

To communicate with the Bot Connector service, you must specify an access token in the Authorization header of each API request, using this format:

Authorization: Bearer ACCESS_TOKEN

To get and use a JWT token for your bot:

1. Your bot sends a GET HTTP request to the MSA Login Service.
2. The response from the service contains the JWT token to use.
3. Your bot includes this JWT token in the authorization header in requests to the Bot Connector service.

Your bot identity can be managed in Azure in a few different ways.

• As a user-assigned managed identity, so that you don't need to manage the bot's credentials yourself.
• As a single-tenant app.
• As a multi-tenant app.

Request an access token based on your bot's application type.

POST https://login.microsoftonline.com/botframework.com/oauth2/v2.0/token
Host: login.microsoftonline.com
Content-Type: application/x-www-form-urlencoded

grant_type=client_credentials&client_id=MICROSOFT-APP-ID&client_secret=MICROSOFT-APP-PASSWORD&scope=https%3A%2F%2F
api.botframework.com%2F.default

If your application is authorized by the login service, the JSON response body will specify your access token, its type, and its expiration (in seconds).

When adding the token to the Authorization header of a request, you must use the exact value that is specified in this response—don't escape or encode the token value. The access token is valid until its expiration. To prevent token expiration from impacting your bot's performance, you may choose to cache and proactively refresh the token.

This example shows a response from the Microsoft Entra ID account login service:

HTTP/1.1 200 OK
... (other headers)

{
    "token_type":"Bearer",
    "expires_in":3600,
    "ext_expires_in":3600,
    "access_token":"eyJhbGciOiJIUzI1Ni..."
}

When you send an API request to the Bot Connector service, specify the access token in the Authorization header of the request using this format:

Authorization: Bearer ACCESS_TOKEN

All requests that you send to the Bot Connector service must include the access token in the Authorization header. If the token is correctly formed, isn't expired, and was generated by the Microsoft Entra ID account login service, the Bot Connector service will authorize the request. Additional checks are performed to ensure that the token belongs to the bot that sent the request.

The following example shows how to specify the access token in the Authorization header of the request.

POST https://smba.trafficmanager.net/teams/v3/conversations/12345/activities
Authorization: Bearer eyJhbGciOiJIUzI1Ni...

(JSON-serialized Activity message goes here)

header:
{
  typ: "JWT",
  alg: "RS256",
  x5t: "<SIGNING KEY ID>",
  kid: "<SIGNING KEY ID>"
},
payload:
{
  aud: "https://api.botframework.com",
  iss: "https://sts.windows.net/d6d49420-f39b-4df7-a1dc-d59a935871db/",
  nbf: 1481049243,
  exp: 1481053143,
  appid: "<YOUR MICROSOFT APP ID>",
  ... other fields follow
}

When the Bot Connector service sends a request to your bot, it specifies a signed JWT token in the Authorization header of the request. Your bot can authenticate calls from the Bot Connector service by verifying the authenticity of the signed JWT token.

To authenticate calls from the Bot Connector service:

1. Your bot gets the JWT token from the authorization header in requests sent from the Bot Connector service.
2. Your bot gets the OpenID metadata document for the Bot Connector service.
3. Your bot gets the list of valid signing keys from the document.
4. Your bot verifies the authenticity of the JWT token.

The OpenID metadata document specifies the location of a second document that lists the Bot Connector service's valid signing keys. To get the OpenID metadata document, issue this request via HTTPS:

GET https://login.botframework.com/v1/.well-known/openidconfiguration

The following example shows an OpenID metadata document that is returned in response to the GET request. The jwks_uri property specifies the location of the document that contains the Bot Connector service's valid signing keys.

{
    "issuer": "https://api.botframework.com",
    "authorization_endpoint": "https://invalid.botframework.com",
    "jwks_uri": "https://login.botframework.com/v1/.well-known/keys",
    "id_token_signing_alg_values_supported": [
      "RS256"
    ],
    "token_endpoint_auth_methods_supported": [
      "private_key_jwt"
    ]
}

To get the list of valid signing keys, issue a GET request via HTTPS to the URL specified by the jwks_uri property in the OpenID metadata document. For example:

GET https://login.botframework.com/v1/.well-known/keys

The response body specifies the document in the JWK format but also includes an additional property for each key: endorsements.

The endorsements property within each key contains one or more endorsement strings that you can use to verify that the channel ID specified in the channelId property within the Activity object of the incoming request is authentic. The list of channel IDs that require endorsements is configurable within each bot. By default, it will be the list of all published channel IDs, although bot developers may override selected channel ID values either way.

To verify the authenticity of the token that was sent by the Bot Connector service, you must extract the token from the Authorization header of the request, parse the token, verify its contents, and verify its signature.

JWT parsing libraries are available for many platforms and most implement secure and reliable parsing for JWT tokens, although you must typically configure these libraries to require that certain characteristics of the token (its issuer, audience, and so on) contain correct values. When parsing the token, you must configure the parsing library or write your own validation to ensure the token meets these requirements:

1. The token was sent in the HTTP Authorization header with "Bearer" scheme.
2. The token is valid JSON that conforms to the JWT standard.
3. The token contains an "issuer" claim with value of https://api.botframework.com.
4. The token contains an "audience" claim with a value equal to the bot's Microsoft App ID.
5. The token is within its validity period. Industry-standard clock-skew is 5 minutes.
6. The token has a valid cryptographic signature, with a key listed in the OpenID keys document that was retrieved in Step 3, using the signing algorithm that is specified in the id_token_signing_alg_values_supported property of the Open ID Metadata document that was retrieved in Step 2.
7. The token contains a "serviceUrl" claim with value that matches the serviceUrl property at the root of the Activity object of the incoming request.

If endorsement for a channel ID is required:

• You should require that any Activity object sent to your bot with that channel ID is accompanied by a JWT token that is signed with an endorsement for that channel.
• If the endorsement isn't present, your bot should reject the request by returning an HTTP 403 (Forbidden) status code.

Implementers shouldn't expose a way to disable validation of the JWT token that is sent to the bot.

header:
{
  typ: "JWT",
  alg: "RS256",
  x5t: "<SIGNING KEY ID>",
  kid: "<SIGNING KEY ID>"
},
payload:
{
  aud: "<YOU MICROSOFT APP ID>",
  iss: "https://api.botframework.com",
  nbf: 1481049243,
  exp: 1481053143,
  ... other fields follow
}

The Bot Framework Emulator is a desktop tool that you can use to test the functionality of your bot. Although the Bot Framework Emulator uses the same authentication technologies as described above, it's unable to impersonate the real Bot Connector service. Instead, it uses the Microsoft App ID and Microsoft App Password that you specify when you connect the Emulator to your bot to create tokens that are identical to those that the bot creates. When the Emulator sends a request to your bot, it specifies the JWT token in the Authorization header of the request—in essence, using the bot's own credentials to authenticate the request.

If you're implementing an authentication library and want to accept requests from the Bot Framework Emulator, you must add this additional verification path. The path is structurally similar to the Connector -> Bot verification path, but it uses MSA's OpenID document instead of the Bot Connector's OpenID document.

To authenticate calls from the Bot Framework Emulator:

1. Your bot gets the JWT token from the authorization header in requests sent from the Bot Framework Emulator.
2. Your bot gets the OpenID metadata document for the Bot Connector service.
3. Your bot gets the list of valid signing keys from the document.
4. Your bot verifies the authenticity of the JWT token.

The OpenID metadata document specifies the location of a second document that lists the valid signing keys. To get the MSA OpenID metadata document, issue this request via HTTPS:

GET https://login.microsoftonline.com/botframework.com/v2.0/.well-known/openid-configuration

The following example shows an OpenID metadata document that is returned in response to the GET request. The jwks_uri property specifies the location of the document that contains the valid signing keys.

{
    "authorization_endpoint":"https://login.microsoftonline.com/common/oauth2/v2.0/authorize",
    "token_endpoint":"https://login.microsoftonline.com/common/oauth2/v2.0/token",
    "token_endpoint_auth_methods_supported":["client_secret_post","private_key_jwt"],
    "jwks_uri":"https://login.microsoftonline.com/common/discovery/v2.0/keys",
    ...
}

To get the list of valid signing keys, issue a GET request via HTTPS to the URL specified by the jwks_uri property in the OpenID metadata document. For example:

GET https://login.microsoftonline.com/common/discovery/v2.0/keys
Host: login.microsoftonline.com

The response body specifies the document in the JWK format.

To verify the authenticity of the token that was sent by the Emulator, you must extract the token from the Authorization header of the request, parse the token, verify its contents, and verify its signature.

JWT parsing libraries are available for many platforms and most implement secure and reliable parsing for JWT tokens, although you must typically configure these libraries to require that certain characteristics of the token (its issuer, audience, and so on) contain correct values. When parsing the token, you must configure the parsing library or write your own validation to ensure the token meets these requirements:

1. The token was sent in the HTTP Authorization header with "Bearer" scheme.
2. The token is valid JSON that conforms to the JWT standard.
3. The token contains an "issuer" claim with one of the highlighted values for non governmental cases. Checking for both issuer values will ensure you're checking for both the security protocol v3.1 and v3.2 issuer values.
4. The token contains an "audience" claim with a value equal to the bot's Microsoft App ID.
5. The Emulator, depending on the version, sends the AppId via either the appid claim (version 1) or the authorized party claim (version 2).
6. The token is within its validity period. Industry-standard clock-skew is 5 minutes.
7. The token has a valid cryptographic signature with a key listed in the OpenID keys document that was retrieved in Step 3.

If the token doesn't meet all of these requirements, your bot should terminate the request by returning an HTTP 403 (Forbidden) status code.

header:
{
  typ: "JWT",
  alg: "RS256",
  x5t: "<SIGNING KEY ID>",
  kid: "<SIGNING KEY ID>"
},
payload:
{
  aud: "<YOUR MICROSOFT APP ID>",
  iss: "https://sts.windows.net/d6d49420-f39b-4df7-a1dc-d59a935871db/",
  nbf: 1481049243,
  exp: 1481053143,
  ... other fields follow
}

See also the highlighted values for non governmental cases.

• Troubleshooting Bot Framework authentication
• Bot Framework Activity schema
• JSON Web Token (JWT) draft-jones-json-web-token-07
• JSON Web Signature (JWS) draft-jones-json-web-signature-04
• JSON Web Key (JWK) RFC 7517