    using System.Security.Cryptography;
    ...
    using(RandomNumberGenerator rng = new RNGCryptoServiceProvider())
    {
        byte[] tokenData = new byte[32];
        rng.GetBytes(tokenData);

        string token = Convert.ToBase64String(tokenData);
    }


  [1]: http://tools.ietf.org/html/rfc4122#section-6

**Upd 2022**
in .Net 6 `RNGCryptoServiceProvider()` is obsolete, usage of static methods of `RandomNumberGenerator` is recommended
```
private string GetRandomlyGenerateBase64String(int count)
{
    return Convert.ToBase64String(RandomNumberGenerator.GetBytes(count));
}

That depends on what you mean by fast...

There is no really fast secure random generator. If you want fast, you should use the regular Random class. If you want secure you should use the random generator in the Cryptography namespace, but that is significantly slower. You simply can&#39;t have both.

in vi, search and replace, how do you escape a &#39;/&#39; (forward slash) so that it is correct. Say in a path.

like: /Users/tom/documents/pdfs/

    :%s//Users/tom/documents/pdfs//&lt;new text&gt;/g  --FAILS (obviously)

    :%s/\/Users/tom/documents/pdfs\//&lt;new text&gt;/g -- FAILS with a trailing error

    :%s/&#39;/Users/tom/documents/pdfs/&#39;/&lt;new text&gt;/g -- FAILS with a trailing error

What am I missing?

/ in vi Search and replace?

I&#39;d like to disable the automatic merge feature when checking in a file to TFS that another developer has worked on so that I always need to merge manually. Is there any way to do this?

Is it possible to disable the auto-merge option in Visual Studio Team System 2008? If so how?

Is there any fast implementation of [cryptographically secure pseudorandom number generator][1] (CSPRNG) for C# 3.0 (.NET Framework 3.5), for authentication tokens?

  [1]: http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator

How can I generate a cryptographically secure pseudorandom number in C#?

<p>Is there any fast implementation of <a href="http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator" target="_blank" rel="noopener noreferrer">cryptographically secure pseudorandom number generator</a> (CSPRNG) for C# 3.0 (.NET Framework 3.5), for authentication tokens?</p>


Is there a way to move an item of say id=10 as the first item in a list using LINQ?

&lt;pre&gt;
Item A - id =5
Item B - id = 10
Item C - id =12
Item D - id =1&lt;/pre&gt;

In this case how can I elegantly move Item C to the top of my `List&lt;T&gt;` collection?

This is the best I have right now:

    var allCountries = repository.GetCountries();
    var topitem = allCountries.Single(x =&gt; x.id == 592);  
    var finalList = new List&lt;Country&gt;();
    finalList.Add(topitem);
    finalList = finalList.Concat(allCountries.Where(x=&gt; x.id != 592)).ToList();

Use LINQ to move item to top of list

I have a `System.Drawing.Image` in my program. The file is not on the file system it is being held in memory. I need to create a stream from it. How would I go about doing this?

System.Drawing.Image to stream C#

Is it necessary to acquire a lock on a variable before reading it from multiple threads?

C# multi-threading: Acquire read lock necessary?

How do I go about changing what happens when a user clicks the close (red X) button in a Windows Forms application (in C#)?

Override standard close (X) button in a Windows Form

I need to determine whether or not two sets contains exactly the same elements. The ordering does not matter.

For instance, these two arrays should be considered equal:

    IEnumerable&lt;int&gt; data = new []{3, 5, 6, 9};
    IEnumerable&lt;int&gt; otherData = new []{6, 5, 9, 3}

One set cannot contain any elements, that are not in the other.

Can this be done using the built-in query operators? And what would be the most efficient way to implement it, considering that the number of elements could range from a few to hundreds?


LINQ: Determine if two sequences contains exactly the same elements

For each of our binary assets we generate a MD5 hash. This is used to check whether a certain binary asset is already in our application. But is it possible that two different binary assets generate the same MD5 hash. So is it possible that two different strings generate the same MD5 hash?

Can two different strings generate the same MD5 hash code?

I have two applications running in the same java virtual machine, and both use different keystores and truststores.

A viable option would be use a single keystore and import all the other ones into the shared keystore (e.g. keytool -import), but it would really help my requirements if I could use separate keystores for separate applications running in the same jvm.

I could set the keystore and truststores to be used as jvm parameters or system properties as follows:

    java -Djavax.net.ssl.keyStore=serverKeys 
    -Djavax.net.ssl.keyStorePassword=password 
    -Djavax.net.ssl.trustStore=serverTrust 
    -Djavax.net.ssl.trustStorePassword=password SSLApplication

or

    System.setProperty(&quot;javax.net.ssl.keyStore&quot;,&quot;serverKeys&quot;)


But the problem with this approach is that it specifies the keystore/truststore to be used at a JVM level, thus all applications running in the same JVM gets the same keystore/truststore.

I have also tried creating a custom SSLContext and setting it as the default, but it also sets the context for all applications running in the same JVM.

    SSLContext context = SSLContext.getInstance(&quot;SSL&quot;);
    context.init(kms, tms, null);
    SSLContext.setDefault(context);

I want to be able use different keystores/truststores without modifying individual application codes. 

**A solution that can *dynamically register multiple key stores* in addition to the default keystore/certs in jre into jvm would be great.**

    
 The solution will work in this way: 
    
 - When JVM boots, it loads all the default certs/keystores 
    from jre/certs folder (default java behaviour when no keystores specified).
 - When App 1 loads it registers its keystores, 
 - then when App 2 loads it registers its keystores...


Please let me know your ideas or solutions.
Thanks in advance!

Registering multiple keystores in JVM

Up to what string length is it possible to use MD5 as a hash without having to worry about the possibility of a collision?

This would presumably be calculated by generating an MD5 hash for every possible string in a particular character set, in increasing length, until a hash appears for a second time (a collision). The maximum possible length of a string without a collision would then be one character less than the longest of the colliding pair.

Has this already been tested for MD5, SHA1, etc?

What&#39;s the shortest pair of strings that causes an MD5 collision?

For a webapplication, when HTTPS is not available as a security measure, is it possible to still make the login somewhat secure? E.g.:

- Tokenize logins, to make repeat attacks difficult?
- Somehow encrypt the sent password from a HTML password field?

In particular I&#39;m using CakePHP and an AJAX POST call to trigger authentication (includes provided username and password).

Update on the problem:

 - HTTPS is not available. Period. If you don&#39;t like the the situation, consider it a theoretical question.
 - There are no explicit requirements, you have whatever HTTP, PHP and a browser (cookies, JavaScript etc.) offers in real life (no magic RSA binaries, PGP plugins).
 - Question is, what is the best, you can make out of *this* situation, that is better than sending the passwords plaintext. Knowing the drawbacks of each such solutions is a plus.
 - Any improvement better than plain passwords is welcome. We do not aim for a 100% l33tG0Dhx0r-proff solution. Difficult to crack is better than complicated to hack which is better than a trivial sniffing revealing the password.

Login without HTTPS, how to secure?

This is how I started to get a `md5` hash from a `string`:

    import &quot;crypto/md5&quot;
    
    var original = &quot;my string comes here&quot;
    var hash = md5.New(original)

But obviously this is not how it works. Can someone provide me a working sample for this?

Content Type	Original Author	Original Content on Stackoverflow
Question	Alon Gubkin	View Question on Stackoverflow
Solution 1 - C#	John Gietzen	View Answer on Stackoverflow
Solution 2 - C#	Serg.ID	View Answer on Stackoverflow
Solution 3 - C#	Guffa	View Answer on Stackoverflow

How can I generate a cryptographically secure pseudorandom number in C#?

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

Is it possible to disable the auto-merge option in Visual Studio Team System 2008? If so how?

/ in vi Search and replace?

Attributions