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I'm creating a web based mobile application. My concern is that, the payload of the JWT token can be decoded from the JWT WEBSITE even without having the key. It shows Invalid Signature error, but still shows the payload included in the token. I'm wondering how much secure is using the JWT token with this scenario. Here is a sample token generated by my API - eyJhbGciOiJIUzUxMiJ9.eyJzdWIiOiJKb2UiLCJuYW1lIjoidnl3diJ9.8xeKufZ-U5ksijK2fCeU7gnZ5Xg-eUTqlZ2SdxrslklHNm519xYx-0DkhEyNe2NRhMUNfyhNsnkpZWim9lqi5w

May be my understanding about JWT is not enough, Is there any solution for this?

Arshad
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Vihanga Yasith
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  • Possible duplicate of [If you can decode JWT how are they secure?](https://stackoverflow.com/questions/27301557/if-you-can-decode-jwt-how-are-they-secure) – jps Apr 25 '18 at 14:42
  • JWT can be signed (JWS - what you mentionned in your question), encrypted (JWE - see [RFC7516](https://tools.ietf.org/html/rfc7516)) or both (signed then encrypted - in this order only). If you need JWE support for PHP, you can have a look at https://github.com/web-token – Spomky-Labs Apr 26 '18 at 09:19

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From the jwt.io page:

When should you use JSON Web Tokens?

Here are some scenarios where JSON Web Tokens are useful:

Authentication:

This is the most common scenario for using JWT. Once the user is logged in, each subsequent request will include the JWT, allowing the user to access routes, services, and resources that are permitted with that token. Single Sign On is a feature that widely uses JWT nowadays, because of its small overhead and its ability to be easily used across different domains.

Information Exchange:

JSON Web Tokens are a good way of securely transmitting information between parties. Because JWTs can be signed—for example, using public/private key pairs—you can be sure the senders are who they say they are. Additionally, as the signature is calculated using the header and the payload, you can also verify that the content hasn't been tampered with.

So it is secure. You only need to verify the token with the keys and never send sensitive data (because it can be decrypted).

Ron Nabuurs
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