Current capability in Apache Knox -
Knox has pac4j provider (https://knox.apache.org/books/knox-0-12-0/user-guide.html#Pac4j+Provider+-+CAS+/+OAuth+/+SAML+/+OpenID+Connect) that provides OIDC support ( https://knox.apache.org/books/knox-0-12-0/user-guide.html#For+OpenID+Connect+support:) However this only works for UI applications.
For REST API -> we need to use JWT token provider ( https://knox.apache.org/books/knox-0-12-0/user-guide.html#JWT+Provider) that takes .pem file ( certificate with public key to decrypt the token) as argument.
Implementation class -> https://github.com/apache/knox/blob/master/gateway-provider-security-jwt/src/main/java/org/apache/knox/gateway/provider/federation/jwt/filter/JWTFederationFilter.java - takes (public static final String SSO_VERIFICATION_PEM = "sso.token.verification.pem" ) as argument.
This .pem file is parsed to get the public key to validate the token.
// token verification pem
String verificationPEM = filterConfig.getInitParameter(SSO_VERIFICATION_PEM);
// setup the public key of the token issuer for verification
if (verificationPEM != null)
Option 1 - We can change the code to pass the public key and use it for token validation. Down side is every time we change the key there should be a Knox config change.
Option 2 - We can change the code to pass the JWKS verification url and if a key is changed - no knox config change is required. Change done to support using JWKS verification url to validate the token :
We selected Option 2 to make things more robust.
Class JWTFederationFilter was changed to get an additional parameter (JWKS verification url) and code to use this url to get the public key and then use this to validate the token. This approach will make it easy to maange for key rotation.
Library used is - https://github.com/okta/okta-jwt-verifier-java