Tuesday, August 25, 2015

How to make .Net 4.0 & 4.5 use TLS 1.2

Basics of HTTP(S)

Unless its not for fun, all the web sites need to be hosted using http(s). Is http(s) that much important? I will say yes. Otherwise, there are chances that our site will be viewed by people with different content than what we published. The web page is not directly sent from webserver to the client computer. It goes through various devices which can manipulate the content inside the site. eg: I as a free Wi-Fi provider can inject my own ads into the sites if they are simply using plain http connection. There were incidents happened as well.

Yes, it is important to have our web site served via http(s) to make sure our customers are seeing what we are sending them. How http(s) is solving this. Simply saying, it uses encryption when the web page contents are transmitted. So no one can see the content who has access to the intermediate devices. Even if they inject some content, it won't get displayed in our browser as the browser will not be able to decrypt the modified contents.

People who are curious about internal will have many questions by now. If our browser for example Chrome can decrypt the content why can't someone who has Chrome browser source code decrypt the same to see the contents?

Welcome to the world of security!!! There are concepts of encryption keys. Only people with the key can decrypt the encrypted content. Ok in this case if we have the key to decrypt the contents why can the attacker obtain the same key from the webserver by accessing the same site from the browser? That is solved with key exchange and usage of asymmetric and symmetric encryptions wisely. What is the key exchange? It is a sequence of steps involved to establish communication between 2 parties and here its web server and the client browser. This process is called the secure HTTP protocol.

Its enough and getting more complicated. Interested readers can please go through the links below to understand it more. 

Others just continue on the assumption that http(s) is the silver bullet to make sure what our viewers seeing is what we sent from the server.

Versions of http(secure)

Ensuring security is always a continuous process. There are chances that there may be a new flaw in the protocol in the future and we need to fix that issue. It becomes the next version of the protocol. When the issue is fixed by specs the existing web servers and browsers also needs to be fixed and it leads to their next version or patch. 

But can we expect all the people in the world update their browser as soon as the new fixed version or patch is released? Can the new fixed browsers assume that all the web servers its communicated are updated with the latest protocol version? Absolutely no. This requires different versions of this communication protocol to be live side by side in the internet. It is the duty of the communicators to settle in what protocol to be used. When we say protocol it includes the encryption details, key exchange details, etc...

Wiki will give more details on secure HTTP versions and the latest as of today is TLS 1.2 and TLS 1.3 is in the draft.


As we saw earlier, https is a protocol before starting both parties involved in communication needs to agree on the method. It is not much complicated. Obviously, one party needs to tell that what it is supported and the server selects the latest technique. Though one party is capable of using the latest protocol, it may not use that as the other end doesn't know and this is called fallback.

Check what is our client browser is using

We saw that http(s) will solve a big security issue. It needs a server-side webserver software and client-side browser software who understands the encryption algorithms. Also, it is versioned

Is our browser capable of working with latest http(s) which is TLS 1.2? Just browse to the below URL to see what is the protocols supported in our browser.


They provide API as well which our application can call and understand what it can support. We will be seeing how an application can check this shortly


Check whether the web site is using SSL/TLS?

Similarly, if we want to check whether a particular site is using secure HTTP go to below URL and enter the web site URL.


Tools to inspect the network communication

If we want to ensure the protocol at the low levels of the system, we can use tools such as Wireshark and all. Those tools help us to inspect the messages in the byte level.

How to host a web site in https

Whatever we discussed above was all general and nothing related to software development. Let's see how a web site can be hosted with a secure HTTP protocol.

The basic need for this is a certificate which is used as a key in encryption. We can create a self sighed certificate or buy from the certificate-issuing authority. Once we have the certificate, it can be associated with our web site via the web server. How to associate the certificate with web site changes from technology to technology.  Below is a link which explains how a site can be hosted securely using https protocol in IIS web server.

How to access SSL site from .Net

We can write applications which can request web sites for web pages as well as data in the same way browser application is requesting data. In Microsoft .Net there are many ways such as WebClient, WCF etc...

Below is the code which can be used to access https://www.howsmyssl.com API from C#.Net application.

var response = WebRequest.Create("https://www.howsmyssl.com/a/check").GetResponse();
var responseData = new StreamReader(response.GetResponseStream()).ReadToEnd();

On console we can see response similar to this.

Hosting WCF Service using http(s)

Hosting WCF using http(s) is not much different than hosting a web site using https. Differences mainly include changes in the web.config file to use Transport security. Below is a link which explains how we can host a WCF web service via http(s)

Accessing HTTP(s) WCF Service from .Net client

Similarly when we are consuming WCF service hosted via https, we need to make sure the service client is configured to use Transport security. Below link explains how a .Net client can access http WCF service. Just change the binding security to Transport in web.config

Why TLS 1.2

Let's come to TLS 1.2. As we have seen above, the latest version of the secure HTTP protocol is TLS 1.2. It means there were problems in earlier versions and its fixed in 1.2. So we need to make sure that as a security-conscious user our browsers need to be upgraded to support TLS 1.2. Will upgrading browser make sure all the connections are using TLS 1.2 protocol? 

No, if we are accessing a web site which is hosted in an environment without TLS 1.2, our browser will fall back to an older protocol version. If we want to avoid falling back to TLS 1.2, we can change the settings in all modern browsers such as ChromeFirefox and IE to always use TLS 1.2 and that is recommended.

More interested readers can google and see what are the changes happened in TLS 1.2 which is based on TLS 1.1.

Obviously, as a responsive software engineer, we should make sure all our web applications must be supporting TLS 1.2 which is the latest at this moment. Need to use proper web servers and technologies to support the same. If we are not moving with the crowd it is very difficult to sustain in the market.

Enable TLS 1.2 at OS level

Not every windows operating system is equipped with TLS 1.2 by default. Below is a link explains how to enable TLS 1.2 in Windows 2008R2, Windows 7 and IIS 7.5. I believe people are still using these versions. 


In Windows Server 2012 & Windows 8.1 TLS 1.2 is enabled by default.

Not that this will make sure the TLS 1.2 is enabled at the OS level. Also, the default apps such as IIS web server and IE browser will also follow the same protocol by default. Basically, there is a system-level dll called schannel.dll which is responsible for this secure communication and applications are calling the API provided by it to have secure communication. Obviously, there are applications which are not replying on schannel to do communication. eg: Chrome and Firefox are not using this schannel so they can use TLS 1.2 even when they are running inside Windows Vista.

Similarly, when we say Windows Vista, 2008 and below are not supporting TLS 1.2, we should understand that their schannel.dll doesn't have support for the protocol.

TLS 1.2 and Microsoft.Net

Now let's focus on using TLS 1.2 in the .Net world. We need to make sure that the web sites are served via TLS 1.2 protocol and client apps which are consuming the same need to support TLS 1.2. .Net is running on top of the operating system and mostly its windows. If host windows support TLS 1.2 .Net can also support TLS 1.2 as it relies on schannel.dll1

The first task here is to make sure we are using the right tools and technologies.

TLS 1.2 and .Net Framework 4.5

.Net is also versioned. Versions below 4.5 don't know how to communicate via TLS 1.2.In .Net 4.5 the TLS 1.2 is enabled by default. Simply compile our applications in, Net 4.5 and we will get TLS 1.2 communication for our applications.

How to make .Net 4.0 app talk using TLS 1.2

Technically speaking just recompile the existing older application to .Net 4.5 to get TLS 1.2 support. It sounds simple as everybody expecting that there are no breaking changes in .Net 4.5 and our application will function as is. But if we are serious about delivering quality software we also need to test the entire app in 4.5 before shipping. It really adds cost.

Let's see if there are any ways to use TLS 1.2 by .Net 4.0 apps.

System.dll overwrite

When we install .Net 4.5 its basically adding changes on top of .Net 4.0. In other words, the System.dll used for 4.0 apps will be overwritten to 4.5 version of System.dll. So there are possibilities that .Net 4.0 apps will execute 4.5 code when they access functions in System.dll. Which means if we have .Net 4.5 installed in the machine where our .Net 4.0 is running it can take advantage of TLS1.2. All our solutions below are depending on this factor.

Below links explains the .Net versioning and overwriting.

1. Code change in 4.0 to use TLS 1.2

Now its the matter of changing the default protocol used by 4.0 to TLS 1.2. This can be done by forcefully changing the protocol as below.

ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;//SecurityProtocolType.Tls1.2;

If we look at the SecurityProtocolType enum for .Net 4.0, we will not be able to see the TLS1.2. But in 4.5 we can see that. So .Net 4.0 will not compile if we use TLS1.2 enum value. But if we use the TLS1.2 enum number it will compile and at runtime since the .Net 4.0's System.dll is replaced with 4.5 the cast will work. 

Please note that this will fail if we are running the same app in a machine which don't have 4.5 installed. Recommended only for servers where its easy to manage the .Net version.

2. Registry change to force .Net 4.0 to use TLS 1.2

If we inspect the .Net 4.5 ServicePointManager source code we can see that the default protocol is depending on the below registry entry.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319: SchUseStrongCrypto to DWORD 1

The default value will be 0. Simply change this to 1 to get .Net 4.5 System.dll use TLS 1.2. Since our 4.0 application uses 4.5 System.dll 4.0 gets TLS 1.2 support.


Update 22May2019

Below is the Microsoft official link on .Net and TLS. It talks about .Net 4.7 as well.



1 - This is as of my understanding. Was not able to get any authentic links.
*-As far as my understanding TLS 1.2 support came from .Net 4.5. I am using 4.5.2 currently.

Tuesday, August 18, 2015

Multiple ways to iterate an array in Javascript

Javascript now seems the way to survive in software industry at least for the next 5 years. I have written a post earlier describing why developers should invest time in learning good parts of Javascript. This is small post where I would like to show how many ways are there in Javascript to loop through an array.

The purpose of this post is not to compare and find out which is the best way. For that please refer this link. Lets start.

Simple javascript JSON array

The iteration needs an array at the minimum. Below is an array which we are going to use.

var strings = ["Joy", "George"];

When we iterate we need to have a test mechanism to show the output. I am just defining an output function which handles it. For the time being we are showing in alert box.

function output(msg) {  
Now lets start exploring different ways to iterate this array.

  1. Using for(;;)

  2. This is the simplest way to iterate any collection. It uses a index pointer variable and gets element from the array using that pointer.Below is the code which does it.

    $scope.loopStringsUsingFor = function () {
            for (i = 0; i < strings.length; i++) {
                output("i=" + i + ", strings[i]=" + strings[i]);

    We can see that there is a $scope variable and the function is assigned to it. This is because I am using AngularJS in jsFiddle.net and this is the way I can associate click handler. The jsFiddle.Net linke is given at the end of this post. It will help to see this code running and play around with the same.
    The output will be 2 alert boxes with the below content respectively.

    i=0 , strings[i]=Joy
    i=1 , strings[i]=George
  3. Using for(var in array)

  4. This is similar to the iteration model available in other languages such as C#. It does not need the index variable. But in Javascript, its not working exactly the same way it works in other languages. Lets see the code below

    $scope.loopStringsUsingForIn = function () {
            for (s in strings) {
                output("s=" + s + ", strings[s]=" + strings[s]);

    The difference with the other languages is clear. In other languages s will be the element in the array. But here s is again the index and we need to use that index to get the string object. The output will be

    s=0, strings[s]=Joy
    s=1, strings[s]=George

    If people are coming from other languages, they will expect string object to be available in the s variable but it will never be. 

  5. Using for(var of array)

  6. This is more similar to the iterations of other languages such as C#. But unfortunately this is available  only from ES6 specs which is released in 2015. If we are targeting application towards global audience, this may not work. See the browser compatibility for more details.

    $scope.loopStringsUsingForOf = function () {
            for (s of strings) {

    The output will be 
  7. Using Array.forEach(function(element,index))

  8. Here we are iterating the array and for each element in the array the function which is passed as argument will be invoked. The element will be the actual string value and index will be the pointer. Lets see how this works

    $scope.loopStringsUsingArrayForEach = function () {
            strings.forEach(function (element, index) {
                output("index=" + index + ",element=" + element);

    The output will be as follows

  9. Using Object.keys(array).forEach(function(element,index))

  10. This iterate through the keys in array. Keys is again an array. Which means we need to find the actual object using indexing mechanism. See the code below

    $scope.loopStringsUsingObjectKeysForEach = function () {
            Object.keys(strings).forEach(function (element, index) {
                output("index=" + index + ",element=" + element + ",strings[element]=" + strings[element] + ",strings[index]=" + strings[element]);

    Since its looping through the keys of array it will return index as well as element as 0,1,..Then the indexing mechanism brings the actual data. The output will be as follows


  11. Using Array.map(function(element))

  12. This is another method to execute a function against all the elements in a array. Lets see the code 

    $scope.loopStringsUsingMap= function(){

    The output will be


  13. Using Array.filter

  14. This technique again uses another method named filter defined on Array. Below is the code

    $scope.loopStringsUsingArrayFilter = function () {
            strings.filter(function (element) {
                output("s=" + element);

    Output is same as

  15. Using Array.every(function(element,index))
  16. This is not intended for iterating. But for testing all the elements in the array for condition. If any element fails on test, it won't iterate to next element. The return boolean value indicate whether the test is success or not. If we return false or don't return any value the iteration will not continue to next element. Instead it just stops. Code below

    $scope.loopStringsUsingArrayEvery = function () {
            strings.every(function (element, index) {
                output("element=" + element + ", index ="+index);
                return true;

    Output will be

  17. Using Array.pop()

  18. This is not exactly iterating the array. But its taking each item from the array. Once this loop is completed the array will be empty.

    $scope.loopStringsUsingArrayPop = function () {
            while (s = strings.pop()) {
                output("s=" + s);
            output("length of strings="+strings.length);

    Output will be
    length of strings=0
    There are more methods on Array which we can use for iterating. Please refer the documentation for more details.
  19. Using Symbol.Iterator

  20. This specification came in ES6 in 2015. So only very latest browsers support this. Code goes as below.
    $scope.loopStringUsingIterator = function () {
            var iter = strings[Symbol.iterator]();
            while (s = iter.next().value) {

    Output will be
  21. Using angular.forEach(array,function(element))

  22. Now most of us would be in a state of confusion which one should use. How to make sure which is supported where etc...This is the exact time frameworks comes to help us. Most of the frameworks provide a mechanism to iterate arrays. The below code snippet is applicable only if we are using AngularJS script is included in the html page.

    $scope.loopStringsUsingAngularForEach = function(){

    Output will be 


    This works in most of the places. Similarly jQuery has mechanism to iterate arrays.
If we use these frameworks we can relax from these repeating general concerns of will this work in other browsers and focus on our business problems and features. Why should we bother to a problem which everybody faces and solved already?

There are more complicated scenarios when we deal with complex objects. Explaining every scenario will be very difficult within a post. Will try to address complex objects related things in another post.

Please go to the jsfiddle to see the complete code

Tuesday, August 11, 2015

www.opencontainers.org - Standardizing the software containerization

Good to see that companies are uniting to create a single open source standard for packing software. It started June 22nd,2015. Right now different vendors such as Docker, Inc has their own standards and it would be difficult to get our software ported to another vendor. This open standard should solve this issue.

All the best to http://www.opencontainers.org/

Tuesday, August 4, 2015

SSIS - Index of features

  • Creating package
    • Programmatic creation - https://msdn.microsoft.com/en-us/library/ms345167(v=sql.110).aspx
  • Variables & Parameters
    • Inbuilt System variables list -https://msdn.microsoft.com/en-us/library/ms141788(v=sql.105).aspx
    • System::ExecutionInstanceGUID - The unique identified generated each time a SSIS package executed. This id can be used to correlate the operations and logs in SSIS package.
  • Control flow
    • If condition in package - No out of the box support. Add expression into Disabled property of task
    • For loop http://www.bidn.com/blogs/TomLannen/bidn-blog/2640/ssis-for-loop-containers-part-1
    • Script task
      • Using variables and Parameters in C# script task.
  • Event handling
  • Running package
    • Run the package and capture events using C# .Net.
      • https://msdn.microsoft.com/en-us/library/ms136090(v=sql.105).aspx
    • Run the package by passing parameter values.
    • Run the package by modifying logging file path connection
    • Run the package by injecting logging provider and connection manager
      • https://msdn.microsoft.com/en-us/library/ms136023.aspx
  • Logging
    • Logging from C# script task
      • https://msdn.microsoft.com/en-us/library/ms136131(v=sql.120).aspx
      • Enable logging of script task log entries
    • Logging into sysssislog table.
  • Extending SSIS