Configuring JWT Grant Type

This topic provides instructions on how to configure the JWT grant type. See the following sections for more information.

• Deploying artifacts
• Configure the JWT grant type
• The flow
• JWT Bearer Grant

Deploying artifacts 

1. Place the  org.wso2.carbon.identity.oauth2.grant.jwt-1.0.5.jar downloaded from store in the <IS_HOME>/repository/components/dropins directory.

   If you want to upgrade the  JWT Grant Type (.jar) that is available in your existing WSO2 Identity Server distribution, see upgrade instructions.

2. To register the JWT grant type, configure the <IS_HOME>/repository/conf/identity/identity.xml file by adding a new entry under the <OAuth><SupportedGrantTypes> element. Add a unique identifier between the <GrantTypeName> tags as seen in the code block below. 

   <SupportedGrantType>
       <GrantTypeName>urn:ietf:params:oauth:grant-type:jwt-bearer</GrantTypeName>
       <GrantTypeHandlerImplClass>org.wso2.carbon.identity.oauth2.grant.jwt.JWTBearerGrantHandler</GrantTypeHandlerImplClass>
       <GrantTypeValidatorImplClass>org.wso2.carbon.identity.oauth2.grant.jwt.JWTGrantValidator</GrantTypeValidatorImplClass>
   </SupportedGrantType>

3. To store AUTHZ_USER and USER_DOMAIN values separately, add the SplitAuthzUser3Way property to the OAuth section of the <IS_HOME>/repository/conf/identity/identity.xml file as follows: <SplitAuthzUser3Way>true</SplitAuthzUser3Way>

4. Add the audience values to the JWT token (ID token) in the <IS_HOME>/repository/conf/identity/identity.xml file as follows

   <Audiences>
   	<Audience>https://localhost:9443/oauth2/token</Audience>
   </Audiences>

5. Restart the server.

Configure the JWT grant type

1. Sign in to the WSO2 Identity Server. Enter your username and password to log on to the Management Console. 
2. In the Identity Providers section under the Main tab of the management console, click Add.
3. Provide the following values to configure the IDP:
   • Identity Provider Name: Enter a issuer name (this is used to generate the JWT assertion) as the identity provider name.

   • Identity Provider Public Certificate:   The certificate used to sign the JWT assertion. You can find more information about adding certificate in Configuring an Identity Provider.

   • Alias: Give the name of the alias if the Identity Provider identifies this token endpoint by an alias (e.g.,  https://localhost:9443/oauth2/token)
   See Adding a new identity provider for more information.
   
   
4. Navigate to the Main menu to access the Identity menu. Click Add under Service Providers.
5. Fill in the Service Provider Name and provide a brief Description of the service provider. See Adding a Service Provider for more information.
6. Expand the OAuth/OpenID Connect Configuration and click Configure.
7. Enter a Callback URL. For example, use http://localhost:8080/playground2/oauth2client and click Add.
8. The OAuth Client Key and OAuth Client Secret will now be visible.
   

<JWTGrant>
            <!-- Validate issued at time (iat) of JWT token. The validity can be set using 'IATValidity' configuration.
             Default value is 'true'.
             -->
            <EnableIATValidation>true</EnableIATValidation>
            <!-- Reject the JWT if the iat of JWT is pass a certain time period. Time period is in minutes.
             'EnableIATValidation' configuration should be set to 'true' in order to make use of the validity period.
             Default value is '30' minutes.
             -->
            <IATValidityPeriod>30</IATValidityPeriod>
        </JWTGrant>

The flow

The CURL commands below can be used to retrieve the access token and refresh the token using a JWT.

curl -i -X POST -u <clientid>:<clientsecret> -k -d 'grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&assertion=<JWT>' -H 'Content-Type: application/x-www-form-urlencoded' https://localhost:9443/oauth2/token

The -u flag should specify the “<Client Id>:<Client Secret>” value. The assertion parameter value is the signed base64 encoded JWT. The value of the assertion parameter  MUST contain a single JWT. You can refer JWT Bearer Grant for more information about assertion.

curl -i -X POST -H 'Content-Type: application/x-www-form-urlencoded' -u bBhEoE2wIpU1zB8HA3GfvZz8xxAa:RKgXUC3pTRQg9xPpNwyuTPGtnSQa -k -d 'grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&assertion=eyJhbGciOiJSUzI1NiJ9.eyJleHAiOjE0NTgxNjY5ODUsInN1YiI6ImFkbWluIiwibmJmIjoxNDU4MTA2OTg1LCJhdWQiOlsiaHR0cHM6XC9cL2xvY2FsaG9zdDo5NDQzXC9vYXV0aDJcL3Rva2VuIiwid3NvMi1JUyJdLCJpc3MiOiJqd3RJRFAiLCJqdGkiOiJUb2tlbjU2NzU2IiwiaWF0IjoxNDU4MTA2OTg1fQ.ZcxdoTVEsWoil80ne42QzmsfelMWyjRZJEjUK1c2vMZJjjtrZnsWExyCA5tN6iXYFAXC_7rkFuuNSgOlBi51MNLPZw3WcgGI52j6apGEW92V2tib9zRRWOeLQLAdo8ae8KzLp7kuKZ2XunfQ2WYU9TvvLDm_vp5ruuYz3ZZrJOc' https://localhost:9443/oauth2/token

You would have now received the response from the token endpoint. The response would contain the access token, refresh token, expiry time and token type. 

{"token_type":"Bearer","expires_in":3600,"refresh_token":"b1b4b78e2b0ef4956acb90f2e38a8833","access_token":"615ebcc943be052cf6dc27c6ec578816"} 

JWT Bearer Grant

JWT contains three parts that are separated by dots ".": header, payload, and a signature. The header identifies which algorithm is used to generate the signature.

For example, see the following code block.

{
	"alg":"RS256"
}

The payload contains the claims mentioned below:

• iss (issuer) - The JWT must contain an iss (issuer) claim that contains a unique identifier that identifies the identity provider that issued the JWT.
• sub (subject) - The JWT must contain a sub (subject) claim that identifies the entity that the identity provider or the entity that issued the JWT vouches for.
• aud (audience) - The JWT must contain an  aud (audience) claim which containing a value that identifies the authorization server as an intended audience. This value should be registered as token endpoint alias in the Identity Provider.
• exp (expiration time) - The JWT must contain an exp (expiration) claim that limits the time window during which the JWT can be used.
• nbf (not before) - The JWT may contain a nbf (not before time) claim that forces a JWT to be used only after a specified time.
• iat (issued at) - The JWT may contain an iat (issued at) claim that identifies the time at which the JWT was issued.
• jti (json web token Id) - The JWT may contain jti (JWT ID) claim that provides a unique identifier for the token.
• Other custom claims - JWT may contain claims other than the above mentioned ones. This is the extension point of the JWT specification.

For example, see the following code block.

{  
   "sub":"admin",
   "aud":[  
      "https://localhost:9443/oauth2/token"
   ],
   "nbf":1507546100,
   "iss":"jwtIDP",
   "exp":1507606100,
   "iat":1507546100,
   "jti":"Token56756"
}

The signature is calculated by base64 URL encoding the header and payload and concatenating them with a period as a separator and signing it:

Signature = sign(encodeBase64(header) + '.' + encodeBase64(payload))

The signature must then be base64 URL encoded. JWT assertion can be generated by concatenating these three encoded values with a separator dot ".".

assertion =   encodeBase64(header) + '.' + encodeBase64(payload) + '.' +  encodeBase64(s ignature)

The result is as follows:

eyJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJhZG1pbiIsImF1ZCI6WyJodHRwczpcL1wvbG9jYWxob3N0Ojk0NDNcL29hdXRoMlwvdG9rZW4iXSwibmJmIjoxNTA3NTQ2MTAwLCJpc3MiOiJqd3RJRFAiLCJleHAiOjE1MDc2MDYxMDAsImlhdCI6MTUwNzU0NjEwMCwianRpIjoiVG9rZW41Njc1NiJ9.iGMhjibB0W2QFQlM27gnHp6z47Eybv8cAHk2o2i-xqo2S4uJ_1VppFI4CCJXTj4qzV9vmkJ5HKNAayiTa6wOMXGL4XnwYwpOAoKXvboznlEDNRpw3htW34nLvyUu6PjHbdvAPVjh8kPRwf7esRr2p-luecGvC21mjWdhyGzM4hE