Postman RS256 JWT Signing

postman-rs256-signing.js

var jwtPrivateKey = `-----BEGIN RSA PRIVATE KEY-----
...
-----END RSA PRIVATE KEY-----`;

// Set headers for JWT
var header = {
	'alg': 'RS256',
	'typ': 'JWT'
};

// Prepare timestamp in seconds
var currentTimestamp = Math.floor(Date.now() / 1000);

var payload = {
	'iat': currentTimestamp,
	'exp': currentTimestamp + 60 * 5
};

function generateJwt() {
	eval(pm.globals.get('jsrsasign-js')); // import javascript jsrsasign

	var sHeader = JSON.stringify(header);
	var sPayload = JSON.stringify(payload);

	var signedToken = KJUR.jws.JWS.sign(header.alg, sHeader, sPayload, jwtPrivateKey);

	pm.environment.set('assertionToken', signedToken);
	// console.log('jwt', signedToken);
}

var navigator = {}; // fake a navigator object for the lib
var window = {}; // fake a window object for the lib

if (pm.globals.has('jsrsasign-js')) generateJwt();
else pm.sendRequest(
	'https://kjur.github.io/jsrsasign/jsrsasign-all-min.js',
	function (err, res) {
		if (err) {
			console.log(err);
		} else {
			pm.globals.set('jsrsasign-js', res.text());
			generateJwt();
		}});