[Community Plugin] Kong Upstream JWT Plugin Released!

We at Optum are happy to announce our first ever Kong plugin!

As taken from our README


This plugin will add a signed JWT into the HTTP Header JWT of proxied requests through the Kong gateway. The purpose of this, is to provide means of Authentication, Authorization and Non-Repudiation to API providers (APIs for which Kong is a gateway).

In short, API Providers need a means of cryptographically validating that requests they receive were A. proxied by Kong, and B. not tampered with during transmission from Kong -> API Provider. This token accomplishes both as follows:

  1. Authentication & Authorization - Provided by means of JWT signature validation. The API Provider will validate the signature on the JWT token (which is generating using Kong’s RSA x509 private key), using Kong’s public key. This public key can be maintained in a keystore, or sent with the token - provided API providers validate the signature chain against their truststore.

  2. Non-Repudiation - SHA256 is used to hash the body of the HTTP Request, and the resulting digest is included in the payloadhash element of the JWT body. API Providers will take the SHA256 hash of the HTTP Request Body, and compare the digest to that found in the JWT. If they are identical, the request remained intact during transmission.

Supported Kong Releases

Kong >= 0.12.x



$ luarocks install kong-upstream-jwt


$ git clone https://github.com/Optum/kong-upstream-jwt.git /path/to/kong/plugins/kong-upstream-jwt
$ cd /path/to/kong/plugins/kong-upstream-jwt
$ luarocks make *.rockspec


The plugin requires that Kong’s private key be accessible in order to sign the JWT. We access this via Kong’s overriding environment variable KONG_SSL_CERT_KEY. This is the environment variable can be set as either a windows or Linux environment variable and must contain the path to your .key file. It is used by Kong to override the contents of Kong’s config file, if your path is also set there.

If not already set, it can be done so as follows:

$ export KONG_SSL_CERT_KEY="/path/to/kong/private/key.key"

One last step is to make the environment variable accessible by an nginx worker. To do this, simply add this line to your nginx.conf


Feel free to open issues, or refer to our Contribution Guidelines if you have any questions.

Feel free to offer suggestions and routes for optimization!



We have updates! - https://github.com/Optum/kong-upstream-jwt , we had added a new JWT header argument x5c, this contains a DER formatted public .cer file. We did this because prior design would have been near to impossible to implement cert management from backend API providers and the gateway itself when yearly cert rotation is to occur. In the new design they can parse out the pub header object and convert it to whatever public key object in their language of choice is and validate it against their trust store. No more hands hovering over the enter key to ensure cert swap out at Kong layer and backend occurs at the exact same time due to them storing the public key directly :slight_smile: . Adding the public cert in DER format did increase our JWT size to about 4kb, and we would like to look into ES256 algo for the pub/priv certs to get this even smaller but currently our cert vendor does not support it, so it will be a future improvement down the road!


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