I study Faculty of Information Technology at VUT in Brno and the main aim of my bachelor thesis is a research of developing the cross-platform desktop applications. The adult spends approximately 2.5 hours per day on desktop computers as shown by the statistics that took place between 2008 and 2015. While the time spent on mobile phones increases, the time spent on desktop computers is, on the other hand, not decreasing. In my opinion, this has a great potential in developing a single desktop application that can be run on all major operating systems. An application such as this that can be built via Electron framework.


It is an open-source framework that allows the creation of native desktop applications on Linux, Windows and macOS platforms with web technologies like JavaScript, HTML, and CSS. A combination of Chromium and Node.js makes this possible. The application that is created by Electron has all the benefits of a native desktop application, such as access to the file system or system notifications. It is recommended to use the npm package manager of Node.js while developing the application. With the npm, a developer can record the necessary modules during development into the package.json file, run the application itself, etc.


In the Electron application, there are two types of processes: the main process and the renderer process. Each one has its own unique role. The process that runs script specified in the package.json as the main one is called the main process. The main process runs renderer processes and takes care of communicating with the API of the operating system. It allows developing the application with OS’s native GUI. Each renderer process renders the content of one web page. The renderer process runs in isolation from other renderer processes.

Development basic application

To develop basic Electron application, it is necessary to create three files: firstly, package.json with information about the application. Secondly, JavaScript file which will be run as the first one and, lastly, HTML file for creating GUI of application (i.e. the web page). The folder-structure of basic application can look like:

├── package.json
├── main.js
└── index.html

To run the application, you can download last Electron release from the web and copy app folder to the downloaded application as below and execute binary electron (electron.exe on Windows, etc.).

Folder-structure of Electron application on macOS

└── app/

Folder-structure of Electron application on Windows and Linux

└── app/

Application distribution

After the application is developed, the developer can package the app folder into asar archive instead of distributing the app’s source code. In such a case, the app folder can be replaced, which includes the source code with app.asar package.

There are three options for distribution. The first one is to manually download all the latest versions of Electron for the necessary platforms and copy the application to the appropriate folder. Using the command line, a third-party tool Electron-packager creates also these packages. The second option, which includes creating install files, is to use the tools also from third parties: Electron-builder or Electron-windows-store.The last option, which includes distributing source code instead of package asar, is to use npm package manager.

The tool Electron-builder uses Electron-packager and creates the file needed to install the application. The format of the installer, that Electron-builder supports for Windows is NSIS. The most widely used packages for Linux are the deb, rpm, freebsd and apk. Similarly, for macOS there are dmg, pkg and mas. Electron-builder also supports automatic updates. If there are dependencies to the native operating system, compilation is required on this system. Otherwise, it is possible to compile application on a selected operating system or use some build server such as AppVeyor for Windows and Travis for Linux and macOS.

Other tool developed by Microsoft for compiling Electron applications into the .appx package is called Electron-windows-store. The tool is available from Microsoft PowerShell. Electron-windows-store can be used only in the operating system Windows 10 with Anniversary Update. Application format for windows store will be generated from the package of the Electron-packager tool. Requirements to compile application:

  • You must have a certificate that supports the application
  • The Windows 10 SDK
  • Node.js with a minimum version of 4.

The last option is to distribute only the source code and use the npm package manager to install dependencies and run the application. It is necessary to have all dependencies in the package.json file. Then, user just downloads the source code and executes these commands:

#to install all dependencies
$npm install
#to run application
$npm start

What we do

We create intelligent enterprise office solutions that build smart business and empower employees to be more productive and creative.

Our YSoft SafeQ Workflow Solutions Platform is used by more than 14,000 corporations and SMB organizations from over 120 countries to manage, optimize and secure their print and digital processes and workflows. Our 3D print solutions are focused in the Education sector where they provide unique workflow and cost recovery benefits.

Through YSoft Labs, we experiment with new technologies for potential new products. We accelerate the technology growth of other innovative companies through Y Soft Ventures, our in-house investment arm.


Our Culture

Y Soft culture is defined by our 6 attitudes. We don’t say they are right or better. We say they are ours – created by employees for employees. We are always seeking people who share similar attitudes because our culture should live on through all Y Softers.



Headquartered in the Czech Republic, we employ over 370 dedicated people around the world. Our R&D centers are in Brno, Prague and Ostrava, Czech Republic, but you can also meet Y Softers in North and Latin America, Dubai, Singapore, Japan or Australia. Together we have 17 offices in 16 countries.


R&D – At Y Soft it is a CRAFT

Unlike other technology companies, whose R&D departments only implement the vision of others, Y Soft employees regularly contribute ideas and help shape the direction of new products.
For us, R&D is a craft — a craft we continuously build upon to expand the R&D know-how in the Czech Republic. We believe in DevOps and have finished the first stage in building our own production grade environment. We are also building a core competency in UI design. Our developers transform their talent into solutions with high added value that impress our customers around the world. We inspire each other with our dedication to quality, by using the most up to date technologies, and in designing, developing and integrating our own hardware and software. We challenge ourselves daily to change the world.img_8833

We are building large-scale connected, global systems for demanding customers (nearly 25% of the Fortune Global 500 use Y Soft’s solutions). This level of customer satisfaction is achieved through R&D’s open access to customers and the opportunity to meet with company executives to discuss and influence R&D direction.

We also work with many young startups through our in-house venture arm, which exposes you to new ideas and mentors to see if entrepreneurship is a future path for you. We offer opportunities to work with thesis students at local universities and reward employees who contribute to our intern’s success.


Want more from Y Soft?

We are growing and can offer you an exciting, rewarding career with a wide range of opportunities to utilize your skills and to grow personally and professionally.

In latest project we came across the problem of securing communication, where peers don’t share backend language. Our goal was to securely generate shared secret between Java server and .NET client. Each language supports all features needed for the key agreement, but these features aren’t always compatible, due to different encoding or data representation.

This article should be quick and easy solution how to agree on shared secret between such server and client with hand-on examples. Each subchapter contains concrete example on how to send, receive and process data needed for respected operation. Authentication and signature scheme are similar to guides published internet-wide, the main topic- key agreement is presented with our insights and comments on how to make it work.

The reason I have included all the code snippets even if they are “straight from internet” is that I wanted to simply group all these schemes to one place, so that you don’t have to find examples on Oracle, CodeRanch, StrackOverflow, MSDN Microsoft documentation, … Honestly it was a little bit frustrating for me, so there you go 🙂

If you are interested just in key agreement, feel free to skip right to the key agreement example, as I would like to discuss authentication and signature schemes first in order to prevent attacks on anonymous key agreement.

Please beware of incautious use of the published code. Your protocol might require different configuration and by simple copy-pasting you may introduce some security issues or errors to it.

Certificate based authentication

Consider each peer to have certificate signed by some root CA.

In my examples I’ll be working mostly with byte arrays as it is most universal way to represent data.

In most cases whole certificate chain is transferred to other side. Using one certificate (self-signed) is just simplification of process below.

.NET authentication

Java peer can transform certificate into byte array using Certificate.getEncoded() method. Byte array is then sent to counterpart.

.NET peer parses certificate chain data and stores parsed certificates into List<byte[]> to ease processing.

Code below shows the authentication process. Process differs from standard validation in a way, that we are sending only certificate chain. From the chain peers certificate is extracted. From the rest of received certificate chain we create subchain and check if we were able to create complete chain from peer to Certificate Authority.

For simplicity revocation checks and certificate usage field (OID of the field – are being ignored. In real environment you should definitely check this list and field, but in this article it is not really necessary.

* receivedCertificateChain previously transformed byte array containing whole certificate chain. This chain is transformed
*                          into list of separate certificates from chain 
public bool certificateChainValidation(List<byte[]> receivedCertificateChain)
  var otherSideCertificate = new X509Certificate2(receivedCertificateChain[0]);
  var chain = new X509Chain { ChainPolicy = { RevocationMode = X509RevocationMode.NoCheck, VerificationFlags = X509VerificationFlags.IgnoreWrongUsage } };
  chain.ChainPolicy.ExtraStore.AddRange(receivedCertificateChain.Skip(1).Select(c => new X509Certificate2(c)).ToArray());

  return chain.Build(otherSideCertificate));

Root CA certificate must be trusted by your system to be successfully validated.

Java authentication

.NET peer can transform each certificate into byte array using X509Certificate2.RawData property and send it to counterpart.

First, Java peer needs to define validation parameters and Trust anchor. In this case it’s root CA.

After that, you validate received certificate chain. If method validate(CertPath, PKIXParameters) is processed without any exception, you can consider received certificate chain correctly validated.

* certificatePath received data of certificate chain from counterpart 
public boolean certificateChainValidation(byte[] certificatePath) {
  try {
    //generate Certificate Path from obtained byte array
    CertificateFactory cf = CertificateFactory.getInstance(“X.509”);
    CertPath received = cf.generateCertPath(new ByteArrayInputStream(certificatePath));

    //get all trusted entities from dedicated truststore
    Set<TrustAnchor> trustedCAs = getAnchors();

    //set the list of trusted entities and turn off the revocation check
    //revocation is by default set to true, so if you don't turn it off explicitly, exceptions will bloom
    PKIXParameters params = new PKIXParameters(trustedCAs);

    CertPathValidator cpv = CertPathValidator.getInstance("PKIX");
    //if no exception is thrown during validation process, validation is successful
    cpv.validate(received, params);
  } catch (CertificateException | NoSuchAlgorithmException | InvalidAlgorithmParameterException | CertPathValidatorException e ) {
    throw new CertificateException("Could not validate certificate", e);
    return false;
  return true;

getAnchors() is a method which simply loads all entries from dedicated truststore and returns them as Set<TrustAnchors>.


Without correct signature scheme whole authentication scheme would be compromised, as any attacker would be able to replay intercepted certificate chain. Therefore while sending outgoing certificate chain, each peer has to include signature to it. It is sufficient for such signature to be reasonably short (resp. long) nonce. This nonce should be freshly generated by the communication counterpart and can be sent before authentication attempt (or as an authentication challenge). Nonce could be any-random value or  static counter, but must be definitely unique.

During the key agreement phase, signatures are used to sign public keys that are exchanged between peers to ensure the integrity of data.

.NET signature generation

First you need to use certificate with included private key – PKCS#12 certificates.

Flags as PersistKeySet and Exportable have to be included to certificate loading, as without them you are not able to obtain private key for signatures from the keystore. PersistKeySet flag ensures that while importing certificate from .pfx or .p12 file, you import private key with it. Exportable flag means that you can export imported keys (mainly private key).

As mentioned in this comment we need a little workaround to force crypto provider to use SHA256 hashes.

public byte[] signData(byte[] dataToSign)
  X509Certificate2 cert = new X509Certificate2(PATH_TO_CERTIFICATE, PASSWORD, X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable);
  RSACryptoServiceProvider privateKey = (RSACryptoServiceProvider)cert.PrivateKey;
  RSACryptoServiceProvider rsaClear = new RSACryptoServiceProvider();
  // Export RSA parameters from 'privateKey' and import them into 'rsaClear'
  // Workaround to force RSACryptoServiceProvider use SHA256 hash
  return rsaClear.SignData(dataToSign, "SHA256");

Java signature generation

Straight-forward example presented internet-wide.

* data       data to be signed
* privateKey private key imported from key pair storage
public byte[] signData(byte[] data, PrivateKey privateKey) {
  try {
    Signature signature = Signature.getInstance(signatureType);
    return signature.sign();
  } catch (NoSuchAlgorithmException | SignatureException | InvalidKeyException e) {
    throw new SignatureException(“Could not create signature”, e);
    return null;

.NET signature verification

First thing to mention is, that you shouldn’t create X509Certificate2 object directly from byte arrays (5th tip in this article). Depending on use of your protocol it might result into stalling and slowing whole protocol, what you definitely don’t want. But again, for simplicity I’m creating object from byte array directly. Mitigation of mentioned problem can be seen in linked article.

* signature    signature of received data
* receivedData data received from counterpart. These data were also signed by counterpart to ensure integrity
public bool verifySignature(byte[] signature, byte[] receivedData)
  X509Certificate2 cert = new X509Certificate2(PATH_TO_CERTIFICATE);

  RSACryptoServiceProvider publicKey = (RSACryptoServiceProvider)cert.PublicKey.Key;
  return publicKey.VerifyData(receivedData, "SHA256", signature);

Java signature verification

Straight-forward example presented internet-wide.

* receivedData data received from counterpart
* signature    signature of receivedData
* publicKey    public key associated with privateKey object from "Java signature generation"
public boolean verifyData(byte[] receivedData, byte[] signature, PublicKey publicKey) {
  try {
    Signature signature = Signature.getInstance(“SHA256withRSA”);
    return signature.verify(signature);
  } catch (NoSuchAlgorithmException | SignatureException | InvalidKeyException e) {
    throw new SignatureException(“Could not validate signature”, e);
    return false;


Key pair generation

Both, key pair generation and key agreement use BouncyCastle library (BC) for the crypto operations. During key generation phase, you need to specify key agreement algorithm. In this project we used elliptic curve Diffie-Hellmann (“ECDH”) key agreement. Elliptic curves were used to generate key pair mainly due to their advantages (performance, key size).

.NET key pair generation

The only difference from standard key generation is encoding of generated public key in a way that Java will accept the key and is able to create PublicKey object.

private static AsymmetricCipherKeyPair generateKeypair()
  var keyPairGenerator = GeneratorUtilities.GetKeyPairGenerator("ECDH");
  var ellipticCurve = SecNamedCurves.GetByName(ELLIPTIC_CURVE_NAME);
  var parameters = new ECDomainParameters(ellipticCurve.Curve, ellipticCurve.G, ellipticCurve.N, ellipticCurve.H, ellipticCurve.GetSeed());
  keyPairGenerator.Init(new ECKeyGenerationParameters(parameters, new SecureRandom()));
  return keyPairGenerator.GenerateKeyPair();

Now you need to send public key to other peer. Unfortunately, it is necessary to format public key in following way, otherwise Java peer will not be able to correctly create PublicKey object and create shared secret.

AsymmetricCipherKeyPair keyPair = generateKeypair();
byte[] publicKeyData = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyPair.Public).GetDerEncoded();

Java key pair generation

public static KeyPair generateKeyPair() {
  try {
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    ECNamedCurveParameterSpec ecNamedCurveParameterSpec = ECNamedCurveTable.getParameterSpec(ELLIPTIC_CURVE_NAME);
    KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("ECDH", PROVIDER);
    return keyPairGenerator.generateKeyPair();
  } catch (NoSuchAlgorithmException | InvalidAlgorithmParameterException | NoSuchProviderException e) {
    throw new EncryptionException("Could not generate key pair", e);


Key agreement

.NET key agreement

At this step, you need to beware the issue in C# BoucyCastle library, which results into failed key agreement even if you have correct keys (correct means same data, but different indentation => 0x0059534F4654 is different from 0x59534F4654).

Problem is that BC library creates shared secret as BigInteger. BigIntegers trims all leading zeroes and at conversion from it to byte array these zeroes aren’t included into array.

Unfortunately until publication day issue wasn’t still fixed in BC and you need to check key lengths by yourselves.

private static byte[] DeriveKey(AsymmetricCipherKeyPair myKeyPair, byte[] otherPartyPublicKey)
  IBasicAgreement keyAgreement = AgreementUtilities.GetBasicAgreement(KEY_AGREEMENT_ALGORITHM);

  //check otherPartyPublicKey length

  //shared secret generation
  var fullKey = keyAgreement.CalculateAgreement(PublicKeyFactory.CreateKey(otherPartyPublicKey)).ToByteArrayUnsigned();  
  return fullKey;

Java key agreement

Straight-forward example presented internet-wide.

public SecretKey secretDerivation(PublicKey receivedPublicKey, PrivateKey myPrivateKey) {
  try {
    KeyAgreement keyAgreement = KeyAgreement.getInstance(KEY_AGREEMENT_ALGORITHM, PROVIDER);
    keyAgreement.doPhase(publicKey, true);
    return keyAgreement.generateSecret(“AES”);
  } catch (NoSuchAlgorithmException | InvalidKeyException | NoSuchProviderException e) {
    throw new EncryptionException("Could not generate secret", e);


From these examples You might gain bad feeling as all examples are rather brute and messages aren’t sent/received in no standard way- only as byte arrays. Best way is to exchange protocol messages in more standardized way. By doing so, you start heavily relying on third party library.

More standardized version of protocol should use Cryptographic Message Syntax. We will have a closer look on this option in next blog article.

This is an introduction to UAM project – management server for Universal appliances (new TPv4, eDee and SafeQube) and the Vert.x framework on which it is developed.

There was a need for easy installation and upgrade of OS and applications running on an UA so we needed a system to manage UAs with as little user interaction as possible.
The main requirements are robustness (we will deal with unrealiable networks and possible power outages), small executables (there is limited storage on the SafeQube) and little disk access (we don’t want to wear out our SafeQube flashdisks).

UAThe system has 2 parts:

  • UA management server – server application which will be deployed next to CML and will contain APIs for system administration
  • UA management server proxy – application cluster which will be deployed on SafeQubes and will cache application binaries and configuration

Both applications are developed using Vert.x framework. UAM server uses also database as configuration storage and proxy applications use Hazelcast for clustering.

Vert.x is an application framework for programming servers (especially web servers). It is built on top of Netty so no application container like Tomcat or Jetty is necessary.

I will show several examples of working with Vert.x so you can try out writing your own applications.

Starting a web server is simple:

    .requestHandler(request -> {
        System.out.println("Received request from " + request.remoteAddress().host());

Using this approach is fast, but you have to handle which business logic to call for which endpoint and it can get quite messy.
Fortunately, we can do better using Vert.x web module:

Router router = Router.router(vertx);
router.route("/hello").handler(context -> {
    String name = context.request().getParam("name");
    context.response().end("Hello " + name);

router.get("/ping").handler(context -> {


This way, we can easily separate business logic for our endpoints.

Do you need request logging or security? You can add more routes for same endpoints. Routes are then processed in the order of addition to the router and can call next route in the chain or just end the response.

Router router = Router.router(vertx);
router.get("/secured-resource").handler(context -> {
    if ("password".equals(context.getCookie("securityToken"))) {
    } else {
        context.response().setStatusCode(401).end("sorry, you are not authorized to see the secured stuff");

router.get("/secured-resource").handler(context -> {
    context.response().end("top secret stuff");

Do you want more than just APIs? There are template engines for Handlebars, MVEL, Thymeleaf or Jade if you want to use their functionality.


Things get more interesting when you configure Vert.x instances to form a cluster. Currently, the only production ready cluster manager is built on top of Hazelcast, so we will use it.

VertxOptions options = new VertxOptions();

Vertx.clusteredVertx(options, result -> {
    if (result.succeeded()) {
        Vertx vertx = result.result();
        //initialize what we need
    } else {
        LOGGER.error("Failed to start vertx cluster", result.cause());

As you can see, starting Vert.x cluster isn’t that complicated. Just be careful to set correct cluster host address or you may find out that the cluster doesn’t behave how you would expect.
And what functionality is available for clustered applications? There is clustered event bus, where you can use point-to-point or publish-subscribe messaging. Just register your consumers and send them messages to logical addresses without ever caring on which node the consumer resides.

vertx.eventBus().consumer("/echo", message -> {

vertx.eventBus().send("/echo", "ping");

I hope this short introduction to Vert.x will make you curious to look at its documentation and start writing your own applications on top of it.

One of the systems our team develops is UI for end-users, where users can view and manage their print related data.

The system is designed as a simple web application, where we make AJAX calls to Spring controllers which delegate the calls to two other systems, no database is present.

One of the requirements on the system was to support about 1000 concurrent users. Since Tomcat has by default 200 threads and the calls to the other systems may take long (fortunately it’s not the case at the moment), we have decided to make use of Servlet 3.0 async. This way, each AJAX call from the browser uses up Tomcat thread only for preparation of a call to other system. The calls are handled by our asynchronous library for communication with SafeQ and asynchronous http client for communication with Payment System which both have own threadpools and fill in the response when they get a reply.

Since we depend so much on other systems’ performance, we wanted to monitor the execution time of the requests for better tracking and debugging of production problems.

There are several endpoints for each system and more can come later, so in order to avoid duplication, we have decided to leverage Spring aspect programming support. We have created an aspect for each business service (one for SafeQ, one for Payment System) and it was time to implement the measurement business logic.

In synchronous scenario, things are pretty simple. Just intercept the call, note start and end time and if it took too long, just log it in a logfile.

public Object restTimingAspect(ProceedingJoinPoint joinPoint) throws Throwable {
    long start = System.currentTimeMillis();

    Object result = joinPoint.proceed();

    long end = System.currentTimeMillis();

    long executionInMillis = end - start;
    if (executionInMillis &gt; remoteServiceCallDurationThresholdInMillis) {
        LOGGER.warn("Execution of {} took {} ms.", joinPoint, executionInMillis);

    return result;

This won’t work in our asynchronous case. The call to joinPoint.proceed(), which will make call to other system returns immediately without waiting for a reply. Reply is processed in a callback provided to one of async communication libraries. So we have to do a bit more.

We know the signature of our business methods. One of the arguments is always callback, which will process the reply.

public void getEntitlement(ListenableFutureCallback callback, String userGuid, Long costCenterId)

If we want to add our monitoring logic in a transparent way, we have to create special callback implementation, which will wrap the original callback and track the total time execution.

class TimingListenableFutureCallback implements ListenableFutureCallback {

    private ListenableFutureCallback delegate;
    private StopWatch timer = new StopWatch();
    private String joinPoint;

    public TimingListenableFutureCallback(ListenableFutureCallback delegate, String joinPoint) {
        this.delegate = delegate;
        this.joinPoint = joinPoint;
    public void onSuccess(Object result) {
        logExecution(timer, joinPoint);

    public void onFailure(Throwable ex) {
        logExecution(timer, joinPoint);

And then we have to call the target business method with properly wrapped callback argument.

@Around("remoteServiceMethod() && args(callback,..)")
public Object restTimingAspect(ProceedingJoinPoint joinPoint, ListenableFutureCallback callback) throws Throwable {
    String joinPointName = computeJoinPointName(joinPoint);
    Object[] wrappedArgs = Arrays.stream(joinPoint.getArgs()).map(arg -> {
        return arg instanceof ListenableFutureCallback ? wrapCallback((ListenableFutureCallback) arg, joinPointName) : arg;
    LOGGER.trace("Calling remote service operation {}.", joinPointName);
    return joinPoint.proceed(wrappedArgs);

There is similar implementation for the other async messaging library.

I hope this solution will help you solve similar problems in your applications in an elegant manner 🙂

While choosing the right security layer for messaging via ZeroMQ, there were two main considerations: built-in security CurveZMQ or usage of more conventional TLS backend?

First option is ZeroMQ’s proprietary security protocol based on elliptic curve cryptography and Daniel’s Bernstein NaCl cryptographic library. CurveZMQ utilizes not only Bernstein’s Curve25519 elliptic curve, but also other ciphers, designed by him, as well- f.e. Salsa20 and poly1305. Other NaCl’s ciphers can be found on its web page under Public-key and Secret-key cryptography chapters.

From the beginning this option was really hot candidate to use, as according to papers about performance of Salsa20 and performance of Curve25519, NaCl crypto functions are faster than standard crypto functions. Also the fact that it was already included in ZeroMQ was big plus. Unfortunately NaCl library and its functions were created in years 2008-2010 and aren’t used widely as f.e. AES or SHA are, therefore aren’t matured enough as other libraries, what brings a little bit panic to our mind and ultimately was the cause of not using it.

Second option was the usage of TLS backend- TLSZMQ. This is a demo project of Ian Barber to secure ZeroMQ communication using OpenSSL library. Unfortunately TLS isn’t built into ZeroMQ, so for now this is the only option how to use TLS and ZeroMQ together 🙁

Implementations comparison

To find the best approach we had few requirements to check. Mainly it was the speed of messaging and library and crypto functions maturity, but other requirements such as support and liveliness of implementation, licensing, quality of code also weighted in decision.

From this set of metrics only 2 appeared to be ultimately decisive:

  • Library and crypto functions maturity
  • Speed of messaging

While the maturity of NaCl library was strong argument why not to use CurveZMQ, performance of NaCl mentioned before spoke strongly in favor of it.

To finally resolve which approach to use and determine the total overhead of each implementation I have created performance tests to find out if TLSZMQ could be used in our environment. The test suite for each implementation was designed to be a block of 20 separate tests running for 10 minutes each, to be sure of reliable test outcomes. Even the message sizes were chosen to reflect the size of messages to be really sent in environment.

total persec

At this point, results clearly spoke strongly in favor of CurveZMQ. On the other hand, there was a conflict with maturity of crypto functions used in CurveZMQ and use of single elliptic curve to generate keys. This could cause many problems, if the curve or other functions would be compromised in the future.

At this point I realized that tests were done with OpenSSL’s by default chosen cipher suite RSA-AES256-SHA384 (OpenSSL version 1.0.1p). There is nothing wrong with this cipher suite, but we have to admit that these algorithms were unnecessarily secure (understand with high overhead).

Yes, I know what I just said and that it sounds really bad, but we must also consider the environment of messaging (its encryption) and performance of the system as well. Only after thorough examination we should accommodate ciphers to real requirements and not just use cipher suites with unnecessarily high security (and overhead) to overkill it.

Therefore, tests were rerun with more appropriate (weaker but still strong) cipher suites. The requirement was to get as much close to CurveZMQ performance as possible:

  • elliptic curves used everywhere possible
    • key exchange [ECDH]
    • authentication [ECDSA]

Any EC could be used, not just one.

  • AES doesn’t have to use 256b key as 128b long keys are still considered pretty strong.

From few acceptable cipher suites, this one specific peaked out: ECDSA-AESGCM128-SHA256.

This new finding has shown that new cipher suite increased the messaging performance considerably (sometimes effectively doubling the speed) [see graphs].

From the results one can see, that TLSZMQ isn’t that much inferior to CurveZMQ and due to TLS’s maturity it is a better choice. The final argument is that test results of TLSZMQ were worse, but sufficient in YSoft SafeQ environment, so the choice of implementation was pretty straight-forward.

Truth is, that NaCl and Curve25519 are really fun (and much easier) to play with and I encourage you to at least have a look at them, but in the end TLS backend is more flexible in terms of crypto primitives (ciphers, key generation) and doesn’t bring that much security concerns. And that’s what we are looking for in secured ZeroMQ messaging.