Pre-request script for Postman app to help make requests against the PassKit API

Postman Pre-request Script.js

var apiKey = "passkit_api_key",
    apiSecret = "passkit_api_secret";

var jwtBody = {
    "key": apiKey,
    "exp": Math.floor(new Date().getTime() / 1000) + 30,
    "iat": Math.floor(new Date().getTime() / 1000),
    "url": request.url,
    "method": request.method
};

if (request.hasOwnProperty("data") && request.data !== null && request.data.length > 0) {
    jwtBody.signature = CryptoJS.SHA256(request.data).toString(CryptoJS.enc.Hex);
}

postman.setEnvironmentVariable('jwt', "PKAuth " + generateJWT(jwtBody, apiSecret));

function generateJWT(body, secret) {
    header = {
        "alg": "HS256",
        "typ": "JWT"
    };
    var token = [];
    token[0] = base64url(JSON.stringify(header));
    token[1] = base64url(JSON.stringify(body));
    token[2] = genTokenSign(token, secret);

    return token.join(".");
}

function genTokenSign(token, secret) {
    if (token.length != 2) {
        return;
    }
    var hash = CryptoJS.HmacSHA256(token.join("."), secret);
    var base64Hash = CryptoJS.enc.Base64.stringify(hash);
    return urlConvertBase64(base64Hash);
}


function base64url(input) {
    var base64String = btoa(input);
    return urlConvertBase64(base64String);
}

function urlConvertBase64(input) {
    var output = input.replace(/=+$/, '');
    output = output.replace(/\+/g, '-');
    output = output.replace(/\//g, '_');

    return output;
}