(Node.js) Verify a JWT Created by the Amazon Cognito Service

Demonstrates how to verify a JWT created by the Amazon Cognito Service.

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.

    // The public keys for this example are at https://cognito-idp.us-east-2.amazonaws.com/us-east-2_******/.well-known/jwks.json
    // Let's get them:

    var http = new chilkat.Http();
    var sbJsonKeys = new chilkat.StringBuilder();
    var success = http.QuickGetSb("https://cognito-idp.us-east-2.amazonaws.com/us-east-2_******/.well-known/jwks.json",sbJsonKeys);
    if (success == false) {
        console.log(http.LastErrorText);
        return;
    }

    var jsonKeys = new chilkat.JsonObject();
    jsonKeys.LoadSb(sbJsonKeys);
    jsonKeys.EmitCompact = false;
    console.log(jsonKeys.Emit());

    // Here are the keys:

    // {
    //   "keys": [
    //     {
    //       "alg": "RS256",
    //       "e": "AQAB",
    //       "kid": "1A/L5Fsb2EsEwxy5E0cmCMS1BnMe6Jl6NXiMig4iNwU=",
    //       "kty": "RSA",
    //       "n": "y0w7BJrIJYi ... jKG27z2P3OKw",
    //       "use": "sig"
    //     },
    //     {
    //       "alg": "RS256",
    //       "e": "AQAB",
    //       "kid": "mos6VTJnvDwurY3ghJg6IAPUq+dMwl6CL/iThzJOkzg=",
    //       "kty": "RSA",
    //       "n": "qbIEH-7tg6yrT ... 3Fj94ooTd0w",
    //       "use": "sig"
    //     }
    //   ]
    // }

    // Try the 1st key.
    // jsonKey1: JsonObject
    var jsonKey1 = jsonKeys.ObjectOf("keys[0]");
    if (jsonKeys.LastMethodSuccess == false) {
        console.log("Did not get the 1st JSON public key.");
        return;
    }

    var pubKey1 = new chilkat.PublicKey();
    success = pubKey1.LoadFromString(jsonKey1.Emit());
    if (success == false) {
        console.log(pubKey1.LastErrorText);
        return;
    }

    console.log("Success");

    var jwt = new chilkat.Jwt();

    // I did not include the an actual AWS Cognito token here because our test sample used customer-provided data..
    var token = "eyJ..asXg";

    // First verify the signature.
    var sigVerified = jwt.VerifyJwtPk(token,pubKey1);
    console.log("verified: " + sigVerified);

    // Let's see if the time constraints, if any, are valid.
    // The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
    // If the current system time is before the "nbf" time, or after the "exp" time,
    // then IsTimeValid will return false/0.
    // Also, we'll allow a leeway of 60 seconds to account for any clock skew.
    // Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
    var leeway = 60;
    var bTimeValid = jwt.IsTimeValid(token,leeway);
    console.log("time constraints valid: " + bTimeValid);

    // Now let's recover the original claims JSON (the payload).
    var payload = jwt.GetPayload(token);
    // The payload will likely be in compact form:
    console.log(payload);

    // We can format for human viewing by loading it into Chilkat's JSON object
    // and emit.
    var json = new chilkat.JsonObject();
    success = json.Load(payload);
    json.EmitCompact = false;
    console.log(json.Emit());

    // We can recover the original JOSE header in the same way:
    var joseHeader = jwt.GetHeader(token);
    // The payload will likely be in compact form:
    console.log(joseHeader);

    // We can format for human viewing by loading it into Chilkat's JSON object
    // and emit.
    success = json.Load(joseHeader);
    json.EmitCompact = false;
    console.log(json.Emit());

}

chilkatExample();