Create JWT using RS256 with jwt.sign

JWT.io
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2

The easiest way for you to accomplish that is by performing a client credentials grant from the rule itself. You would represent the API within Auth0 and configure it so that RS256 tokens are issued to it, then you would authorize a suitable client application to perform a client credentials grant.

Finally, you could then do the following from a rule:

function (user, context, callback) {
  var request = require("request");

  var options = { method: 'POST',
    url: 'https://[your_account].auth0.com/oauth/token',
    headers: { 'content-type': 'application/json' },
    body: 
    {
      grant_type: 'client_credentials',
      client_id: '[your_cc_client_id]',
      client_secret: '[your_cc_client_secret]',
      audience: '[your_api_identifier]',
    },
    json: true };

  request(options, function (error, response, body) {
    if (error) return callback(error);

    // Call API with body.access_token...
        
    callback(null, user, context);
  });
}