Creating a JWT token in script using java cyrpto packages

[hamzaathar]

I have created a script include to generate JWT tokens for authorization purposes on a separately hosted web app. 

The script include is in the global scope and accessible to all applications.

I am getting an "Illegal attempt to access class 'javax.crypto.Mac' via script" error when running the script include.

Code snippet:

signHMACSHA256: function(data, secret) {
        var mac = new Packages.javax.crypto.Mac.getInstance("HmacSHA256");
        var secretKey = new Packages.javax.crypto.spec.SecretKeySpec(secret.getBytes(), "HmacSHA256");
        mac.init(secretKey);
        var rawHmac = mac.doFinal(new java.lang.String(data).getBytes());
        return GlideStringUtil.base64Encode(rawHmac).replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
    },

Any solutions to access this package? Or alternate solutions to generating JWT.