(Node.js) Get E-way Bill System Access Token

Sends a request to get an E-way bill system access token.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // First load the public key provided by the E-way bill System
    var pubkey = new chilkat.PublicKey();
    var success = pubkey.LoadFromFile("qa_data/pem/eway_publickey.pem");
    if (success !== true) {
        console.log(pubkey.LastErrorText);
        return;
    }

    // Encrypt the password using the RSA public key provided by eway..
    var password = "my_wepgst_password";
    var rsa = new chilkat.Rsa();
    rsa.Charset = "utf-8";
    rsa.EncodingMode = "base64";

    success = rsa.ImportPublicKeyObj(pubkey);
    if (success !== true) {
        console.log(rsa.LastErrorText);
        return;
    }

    // Returns the encrypted password as base64 (because the EncodingMode = "base64")
    var encPassword = rsa.EncryptStringENC(password,false);
    if (rsa.LastMethodSuccess !== true) {
        console.log(rsa.LastErrorText);
        return;
    }

    // Generate a random app_key.  This should be 32 bytes (us-ascii chars)
    // We need 32 bytes because we'll be doing 256-bit AES ECB encryption, and 32 bytes = 256 bits.
    var prng = new chilkat.Prng();
    // Generate a random string containing some numbers, uppercase, and lowercase.
    var app_key = prng.RandomString(32,true,true,true);

    console.log("app_key = " + app_key);

    // RSA encrypt the app_key.
    var encAppKey = rsa.EncryptStringENC(app_key,false);
    if (rsa.LastMethodSuccess !== true) {
        console.log(rsa.LastErrorText);
        return;
    }

    // Prepare the JSON body for the HTTP POST that gets the access token.
    var jsonBody = new chilkat.JsonObject();
    jsonBody.UpdateString("action","ACCESSTOKEN");
    // Use your username instead of "09ABDC24212B1FK".
    jsonBody.UpdateString("username","09ABDC24212B1FK");
    jsonBody.UpdateString("password",encPassword);
    jsonBody.UpdateString("app_key",encAppKey);

    var http = new chilkat.Http();

    // Add required headers.
    // Use your ewb-user-id instead of "03AEXPR16A9M010"
    http.SetRequestHeader("ewb-user-id","03AEXPR16A9M010");
    // The Gstin should be the same as the username in the jsonBody above.
    http.SetRequestHeader("Gstin","09ABDC24212B1FK");
    http.Accept = "application/json";

    // POST the JSON...
    // resp: HttpResponse
    var resp = http.PostJson2("http://ewb.wepgst.com/api/Authenticate","application/json",jsonBody.Emit());
    if (http.LastMethodSuccess !== true) {
        console.log(http.LastErrorText);
        return;
    }

    var respStatusCode = resp.StatusCode;
    console.log("response status code =" + respStatusCode);
    console.log("response body:");
    console.log(resp.BodyStr);

    if (respStatusCode !== 200) {

        console.log("Failed in some unknown way.");
        return;
    }

    // When the response status code = 200, we'll have either
    // success response like this:
    //  {"status":"1","authtoken":"...","sek":"..."}
    // 
    // or a failed response like this:
    // 
    // {"status":"0","error":"eyJlcnJvckNvZGVzIjoiMTA4In0="}

    // Load the response body into a JSON object.
    var json = new chilkat.JsonObject();
    json.Load(resp.BodyStr);

    var status = json.IntOf("status");
    console.log("status = " + status);

    if (status !== 1) {
        // Failed.  Base64 decode the error
        // {"status":"0","error":"eyJlcnJvckNvZGVzIjoiMTA4In0="}
        // For an invalid password, the error is: {"errorCodes":"108"}
        var sbError = new chilkat.StringBuilder();
        json.StringOfSb("error",sbError);
        sbError.Decode("base64","utf-8");
        console.log("error: " + sbError.GetAsString());
        return;
    }

    // At this point, we know the request was entirely successful.
    var authToken = json.StringOf("authtoken");

    // Decrypt the sek key using our app_key.
    var crypt = new chilkat.Crypt2();
    crypt.CryptAlgorithm = "aes";
    crypt.CipherMode = "ecb";
    crypt.KeyLength = 256;
    crypt.SetEncodedKey(app_key,"us-ascii");
    crypt.EncodingMode = "base64";

    var bdSek = new chilkat.BinData();
    bdSek.AppendEncoded(json.StringOf("sek"),"base64");
    crypt.DecryptBd(bdSek);

    // bdSek now contains the decrypted symmetric encryption key...
    // We'll use it to encrypt the JSON payloads we send.

    // Let's persist our authtoken and decrypted sek (symmetric encryption key).
    // To send EWAY requests (such as to create an e-way bill), we'll just load 
    // and use these pre-obtained credentials.
    var jsonEwayAuth = new chilkat.JsonObject();
    jsonEwayAuth.UpdateString("authToken",authToken);
    jsonEwayAuth.UpdateString("decryptedSek",bdSek.GetEncoded("base64"));
    jsonEwayAuth.EmitCompact = false;

    var fac = new chilkat.FileAccess();
    fac.WriteEntireTextFile("qa_data/tokens/ewayAuth.json",jsonEwayAuth.Emit(),"utf-8",false);

    console.log("Saved:");
    console.log(jsonEwayAuth.Emit());

    // Sample output:
    // {
    //   "authToken": "IBTeFtxNfVurg71LTzZ2r0xK7",
    //   "decryptedSek": "5g1TyTie7yoslU3DrbYATa7mWyPazlODE7cEh5Vy4Ho="
    // 

}

chilkatExample();