Our .net core based web api needs to validate the the JWT access tokens received from third party but trusted AAD. In order to do that token signature validation our web api needs to have public certificate of trusted AAD. This functionality is in POC phase. So how to get/download public certificate (.cer file) of AAD?
I would recommend that you use the standard JWT Bearer authentication scheme which handles this aspect for you.
You specify the Authority and ClientId to it and it'll handle the rest.
But if you are curious about the details,
I can explain a bit.
First you take your authority, e.g. https://login.microsoftonline.com/company.com/v2.0 (or https://login.microsoftonline.com/company.com if you are using v1 tokens).
We add /.well-known/openid-configuration to the authority to get the metadata URL: https://login.microsoftonline.com/company.com/v2.0/.well-known/openid-configuration.
That metadata URL gives us JSON which includes the jwks_uri property.
E.g.:
"jwks_uri":"https://login.microsoftonline.com/tenant-id-here/discovery/v2.0/keys"
When we navigate to this URL, we get the public signing keys for Azure AD.
This is all handled under the covers by the JWT Bearer authentication handler though, so you should not implement it yourself.
Related
I'm trying to validate (and read roles from) a JWT Token. Sadly I can't use any adapter or auto configuration due to my overall application architecture.
It's no problem to decode the token like any other JWT Token, but I wonder if there is a library from Keycloak to archive this goal. (For example Just Parse the token to something like a KeycloakJWTToken and verify it by grabbing the secret from Keycloak Server or so)
Any easy-to-use client or so?
I'm using the Jose4J library:
https://bitbucket.org/b_c/jose4j/wiki/Home
Reading the claims inside a JWT token is straightforward:
import org.jose4j.jwt.JwtClaims;
import org.jose4j.jwt.consumer.JwtConsumer;
import org.jose4j.jwt.consumer.JwtConsumerBuilder;
public void parseJWT(String token) throws Exception {
JwtConsumer consumer = new JwtConsumerBuilder()
.setSkipAllValidators()
.setDisableRequireSignature()
.setSkipSignatureVerification()
.build();
JwtClaims claims = consumer.processToClaims(token);
System.out.println("* Parsed token: "+ claims.getRawJson() );
System.out.println("* Expiration date: " + new Date(claims.getExpirationTime().getValueInMillis()) );
}
More examples are available on GitHub:
https://github.com/pvliesdonk/jose4j/blob/master/src/test/java/org/jose4j/examples/ExamplesTest.java
Last remark: you do not need a key nor a secret to parse the JWT, but if needed, you can use the server (public) key to verify the token was signed by the keycloak server you are trusting.
The JWT website is listing all libraries for Token Signing/Verification:
https://jwt.io/#libraries-io
Keycloak access tokens are indeed JWT tokens. So, you can make full use of existing JWT libraries, including for validation as stated in the Keycloak official documentation:
If you need to manually validate access tokens issued by Keycloak you can invoke the Introspection Endpoint. The downside to this approach is that you have to make a network invocation to the Keycloak server. This can be slow and possibily overload the server if you have too many validation requests going on at the same time. Keycloak issued access tokens are JSON Web Tokens (JWT) digitally signed and encoded using JSON Web Signature (JWS). Because they are encoded in this way, this allows you to locally validate access tokens using the public key of the issuing realm. You can either hard code the realm’s public key in your validation code, or lookup and cache the public key using the certificate endpoint with the Key ID (KID) embedded within the JWS. Depending what language you code in, there are a multitude of third party libraries out there that can help you with JWS validation.
Besides, in Java EE, using the Keycloak Java adapter, the roles are typically mapped on the user Principal and i.e. allows isUserInRole(). That's one of the goals.
Also it is possible to cast the Principal from the SecurityContext as a KeycloakPrincipal, then obtain in turn a KeycloakSecurityContext from it. Using the KeycloakSecurityContext you have access to both ID and Access tokens (when applicable) and can read their properties, attributes and claims.
Note that it is also good practice, and simply useful, to use the Keycloak UI to "evaluate" your tokens. For instance, you can see the generated token in the Client Scopes tab (under Evaluate), as well as evaluate your policies and permissions in the Authorization tab of your Client(s) (under Evaluate).
Cf. https://www.keycloak.org/docs/latest/server_admin/#_client_scopes_evaluate
That's probably the best way to debug and test, while setting up your Client(s).
If you select a user in the Evaluate screen, the following example data is generated:
Generated Access Token (...)
Generated ID Token (...)
Generated User Info (...)
All examples are generated for the particular user and issued for the particular client, with the specified value of scope parameter. The examples include all of the claims and role mappings used.
Source: https://www.keycloak.org/docs/latest/server_admin/#generating-example-tokens-and-user-info
I have written a web application which makes REST API calls to a message broker. The message broker contains already written REST APIs to which can be used to get message broker data. The message broker is written in a way in which each REST API call sends the user name and password which is encoded with base64. I need to make a login to my web app and authenticate it with OAuth.Does anyone know how to do this? How to authenticate the REST APIs with OAuth?
Step 1: Add OAuth 2.0 to your web server. This is very standard with lots of libraries available. You did not specify the Identity Provider that you will use (Google, Facebook, Auth0, Okta, etc), but each vendor has documents and libraries for you to use in your desired language.
Step 2: Add an Authorization Header to your API calls. The standard method is to add the HTTP header Authorization: Bearer access_token when making an API call.
Step 3: Add OAuth token verification to your API. When your API receives a request, it extracts the Authorization header and verifies the Bearer token. How this is done depends on the Identity Provider. For example, some vendors provide a Signed JWT (which you verify with the vendors public certificate), others provide an opaque access token (which you verify by calling the vendor's token endpoint). Add internal caching of tokens so that you don't need to verify on every API call.
If you understand OAuth 2.0 the above steps are straightforward to implement. If you don't Oracle has a set of videos which are excellent for getting started understanding OAuth.
Oracle Cloud Primers
If your desired OAuth implementation does not require users logging in and is a server to server service that you control on both ends, then you can use just part of OAuth which is Signed JWT (JWS). You create a Json data structure with your desired content and sign it with a private key. This creates a token that you can use in the above steps. You would then validate the token using your public key. You can use self-generated keypairs generated by OpenSSL or similar products for your signing and verification.
When you authenticate with an OIDC provider you get back an id token and if you specified scopes for an API you get back an access token so that client applications can make requests to protected resources on the end user's behalf. Typically the access token is also a JWT.
But what is to stop someone from spoofing one of these access tokens, and creating one and passing it to an API? I understand there are safeguards to prevent modification because the signature will be different than what any validation logic is expecting, but what if a malicious user created a brand new one manually? Especially because these tokens can be validated 'in place' by any API that requires an access token (not all API's use the introspection endpoint... especially with a JWT). I do understand there is metadata around the signing keys for JWT's from OpenID Connect providers and that it is available in the OIDC discovery document. For example, here is Google's JWK metadata. Given that you have signing information publicly available, and JWT access token's can be validated without any requests to the OIDC provider, how are JWT's secure? What is preventing a person from creating one and passing it as a bearer token to an API that requires an access token?
But what is to stop someone from spoofing one of these access tokens, and creating one and passing it to an API?
Spoofing and reconstruction of signature is nearly impossible without the private key (assuming you are using asymmetric signing algorithm like RS256) that used for signing the original JWT.
The JWK information available via OIDC discovery document only contains the public key.
Also Use HTTPS for authorization / token exchange to avoid token sniffing.
I am newbie in JSON web token and micro services. I read in an articles that if i share the private, all services can verify user on their own. Then i tried to implement an application to practice.
Basically, I have two services A and B. A is used for authentication. Then, I tried implement a API that required authentication in service B. But when I used a token generated by authentication A in API, 401 status code and "Invalid signature." were returned.
So anyone can explain to me what I did wrong?
"Invalid signature" implies that the secret key that you used to encode the token doesn't match with the secret key you used for decoding it.
Make sure that the secret you are using for encoding and decoding are same.
For more info visit the JWT's site.
First of all the service to service communication only need public key to be shared in case of an asymmetric key pair such as RSA or ECDSA. The public key shared can be used to verify the signature and each service needs to sign JWT using their private key. You have to take care of securing the private key and make public key accessible to other services.
Verifying the user is a completely different use case. The user existence should be checked in database and a password check can be made which is authentication is all about. The JWT can be used to pass the user information along with access right with a signature done by the application using private key so that no one able to generate the same token. NOTICE : Signature is done using private key. In this way you have both authentication and authorisation using JWT.
JWT OAuth2 Token is prefetched from Spring Auth Server and stored in Redis Storage.
I don't want to request access token in OAuth2RestTemplate and I want to use my JWT Token for requests.
Can I do it with OAuth2RestTemplate or I should use usual RestTemplate?
The documentation for spring-security-oauth is useful here, basically the two sections: JWT Tokens and Accessing Protected Resources:
JWT Tokens
To use JWT tokens you need a JwtTokenStore in your Authorization
Server. The Resource Server also needs to be able to decode the tokens
so the JwtTokenStore has a dependency on a JwtAccessTokenConverter,
and the same implementation is needed by both the Authorization Server
and the Resource Server. The tokens are signed by default, and the
Resource Server also has to be able to verify the signature, so it
either needs the same symmetric (signing) key as the Authorization
Server (shared secret, or symmetric key), or it needs the public key
(verifier key) that matches the private key (signing key) in the
Authorization Server (public-private or asymmetric key). The public
key (if available) is exposed by the Authorization Server on the
/oauth/token_key endpoint, which is secure by default with access rule
"denyAll()". You can open it up by injecting a standard SpEL
expression into the AuthorizationServerSecurityConfigurer (e.g.
"permitAll()" is probably adequate since it is a public key).
To use the JwtTokenStore you need "spring-security-jwt" on your
classpath (you can find it in the same github repository as Spring
OAuth but with a different release cycle).
Accessing Protected Resources
Once you've supplied all the configuration for the resources, you can
now access those resources. The suggested method for accessing those
resources is by using the RestTemplate introduced in Spring 3. OAuth
for Spring Security has provided an extension of RestTemplate that
only needs to be supplied an instance of
OAuth2ProtectedResourceDetails.
This basically means to me that you'll use the same spring-security-jwt JwtAccessTokenConverter class in both the authorization server and the resource server and that the token services in each need to be setup with the JwtTokenStore(). The extension to the RestTemplate class they're referring to is the OAuth2RestTemplate from spring-security-oauth2. You'd use it in your resource server with it's JWT smarts being provided by an equivalent token recognizer.
Because the spring-security-oauth2 code is already set up to handle JWT tokens, you just need to provide a few key pieces and let the framework do the heavy lifting of inspecting the token and putting the security into scope for each protected resource.
As it would happen, someone's posted a nice example of this which goes into detail: baeldung spring-security-oauth-jwt example and here: github project of the same including how one could provide a more customized JWT (claims/payload).