Token API

Users need access tokens to invoke APIs subscribed under an application. Access tokens are passed in the HTTP header when invoking APIs. The API Manager provides a Token API that you can  use to generate and renew user and application access tokens. The response of the Token API is a JSON message. You extract the token from the JSON and pass it with an HTTP Authorization header to access the API.

The following topic explain how to generate/renew access tokens and authorize them. WSO2 API Manager supports the four most common authorization grant types and you can also define additional types.

• Exchanging SAML2 Bearer Tokens with OAuth2 - SAML Extension Grant Type
• Generating Access Tokens with Authorization Code - Authorization Code Grant Type
• Generating Access Tokens with NT LAN Manager - NTLM Grant Type
• Generating Access Tokens with User Credentials - Password Grant Type

Also see the following: 

Renewing access tokens

After an access token is generated, sometimes you might have to renew the old token due to expiration or security concerns. You can renew an access token using a refresh token, by issuing a REST call to the Token API with the following parameters.

• The Token API URL is https://localhost:8243/token, assuming that both the client and the Gateway are run on the same server.
• payload: "grant_type=refresh_token&refresh_token=<retoken>". Replace the <retoken> value with the refresh token generated in the previous section.
• headers: Authorization :Basic <base64 encoded string>, Content-Type: application/x-www-form-urlencoded. Replace <base64 encoded string> as appropriate.          

For example, the following cURL command can be used to access the Token API.

curl -k -d "grant_type=refresh_token&refresh_token=<retoken>" -H "Authorization: Basic SVpzSWk2SERiQjVlOFZLZFpBblVpX2ZaM2Y4YTpHbTBiSjZvV1Y4ZkM1T1FMTGxDNmpzbEFDVzhh" -H "Content-Type: application/x-www-form-urlencoded" https://localhost:8243/token

The above REST message grants you a renewed access token along with a refresh token, which you can use the next time you renew the access token. A refresh token can be used only once. At the moment, a refresh token never expires, but we will provide a way to configure an expiration time in a future release.

Revoking access tokens

After issuing an access token, a user or an admin can revoke it in case of theft or a security violation. You can do this by calling Revoke API using a utility like cURL. The Revoke API's endpoint URL is http://localhost:8280/revoke.

Parameters required to invoke this API are as follows:

• The token to be revoked
• Consumer key and consumer secret key. Must be encoded using Base64 algorithm

For example, curl -k -d "token=<ACCESS_TOKEN_TO_BE_REVOKED>" -H "Authorization: Basic Base64Encoded(Consumer key:consumer secret)" http://localhost:8280/revoke.

Configuring the token expiration time

User access tokens have a fixed expiration time, which is set to 60 minutes by default. Before deploying the API Manager to users, extend the default expiration time by editing the <AccessTokenDefaultValidityPeriod> element in <PRODUCT_HOME>/repository/conf/identity.xml.

Also take the time stamp skew into account when configuring the expiration time. The time stamp skew is used to manage small time gaps in the system clocks of different servers. For example, let's say you have two Key Managers and you generate a token from the first one and authenticate with the other. If the second server's clock runs 300 seconds ahead, you can configure a 300s time stamp skew in the first server. When the first Key Manager generates a token (e.g., with the default life span, which is 3600 seconds), the time stamp skew is deducted from the token's life span. The new life span is 3300 seconds and the first server calls the second server after 3200 seconds.

You configure the time stamp skew using the <TimestampSkew> element in <PRODUCT_HOME>/repository/conf/identity.xml. 

When a user access token expires, the user can try regenerating the token as explained in the Renew user tokens section.