I have an android app. It connects with a REST API developed with Jersey. My REST End points are secured with Tokens. Below is how I generate them.
Algorithm algorithm = Algorithm.HMAC256(secret);
String token = JWT.create()
.withClaim("userName","myusername)
.withExpiresAt(expirationDate)
.sign(algorithm);
Below is how I validate the token
public boolean validateTokenHMAC256(String token, String secret) throws UnsupportedEncodingException, JWTVerificationException
{
Algorithm algorithm = Algorithm.HMAC256(secret);
JWTVerifier verifier = JWT.require(algorithm)
.build(); //Reusable verifier instance
DecodedJWT jwt = verifier.verify(token);
Claim usernameClaim = jwt.getClaim("username");
String username = usernameClaim.asString();
System.out.println(username);
return true;
}
In my REST API I have a filter and that filter checks every request to see whether the token is as it is. Below is the code.
@Secured
@Provider
@Priority(Priorities.AUTHENTICATION)
public class AuthenticationFilter implements ContainerRequestFilter{
//private static String authorizationSecret = "ZXW24xGr9Dqf9sq5Dp8ZAn5nSnuZwux2QxdvcH3wQGqYteJ5yMTw5T8DBUJPbySR";
public AuthenticationFilter()
{
System.out.println("test printing");
}
@Override
public void filter(ContainerRequestContext crc) throws IOException
{
String headerString = crc.getHeaderString("Bearer");
System.out.println("bluh: "+headerString);
System.out.println("test printing");
try
{
boolean validateToken = validateToken(headerString, AuthKey.authorizationSecret);
System.out.println("valid");
}
catch(Exception e)
{
System.out.println("invalid");
crc.abortWith(
Response.status(Response.Status.UNAUTHORIZED).build());
}
}
private boolean validateToken(String strToken, String secret) throws UnsupportedEncodingException, JWTVerificationException
{
Token token = new Token();
return token.validateTokenHMAC256(strToken,secret);
}
}
The above code will be called when the user login to the application. However the token will be expired in 60 minutes. I know that after the token is expired either I have to take the user back to sign in screen or refresh the token. I went through the advices in here and here
But I do not understand the following.
How can I figure out whether the token has to be renewed? I thought I should do that after it is expired, but seems that is not the case. If I ask it to refresh in
now<expit will refresh in every request.How can I assign and send this token back to the user? Currently when the user login on, he will get the token and he will save it in a variable. For the refreshed token to work, do I have to call the
loginmethod again (So the token will be sent to the user) or JWT it self will handle the case?How do I actually refersh using java-jwt ?
- How can I figure out whether the token has to be renewed? I thought I should do that after it is expired, but seems that is not the case. If I ask it to refresh in now
You need to refresh the token before it is expired. Decide your policy:
issue a fresh token in every request
issue a fresh token when the current one is close to expire. e.g. 10 min
let client app request a new token when it needs it using a "refresh service" of your api. For example
@GET
@Path("/jwt/refresh")
@Produces(MediaType.TEXT_HTML)
public String refresh(){
//Build a returns a fresh JWT to client
}
- How can I assign and send this token back to the user?
If you issue a fresh token during a request, you can return it in a special header that client will read during processing of the response. If you publish a "refresh" service as described above, then the client will call it independently when the current JWT is close to expire
Redirect to login method is not a good alternative because you will lose the current request
- How do I actually refresh using java-jwt
Just issue a new token