password generation using threading

Question

3.00/5 (2 votes)

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hello, I want to do this work by threading. help me how...

private static string MakePassword4(int pl)
       {
           string possibles =
           "0123456789";
           char[] passwords = new char[pl];
           Random rd = new Random();
           {
               for (int i = 0; i <1000; pl; i++)
               {
                   passwords[i] = possibles[rd.Next(0, possibles.Length)];
               }
           }
           return new string(passwords);
       }


private void button1_Click(object sender, EventArgs e)
 {
 

         listView1.View = View.Details;
         listView1.Items.Clear();
         for (int j = 0; j<1000;j++)         {
             temp = MakePassword11(length);
             Refresh();
             listView1.GridLines = true;
             listView1.Items.Add(temp.ToString());
         }
        return;
     }

[edit]Code block added - OriginalGriff[/edit]

Posted 22-Mar-11 1:33am

situ21

Updated 22-Mar-11 2:50am

v3

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Ankit Rajput 22-Mar-11 7:38am

Hi Satendra,

Can you please explain in detail which functionality you want to put in threading?

Regards
Ankit

[no name] 22-Mar-11 7:51am

Also, the posted code is quite unclear and should not work at all. In button1_Click(): for (int j = 0; j <str;> This loop looks a little mishappen. Also, no variable 'str' is declared. Then, a method MakePasswordll() is called, the posted code only has a MakePassword4() method. Is this the one to be called?

2 solutions

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OriginalGriff · Accepted Answer · 2011-03-22T01:43:00

Solution 2

Why would you want to do that via threading? Do you think it is going to take considerable amounts of time?
If your MakePassword11 method is anything like your MakePassword4 method, then there will be more overhead in setting up and destroying the new thread than should be taken up by the method - and it will be nowhere near as clear what is happening.

Can I also suggest that a password which consists only of numeric digits is a bit on the insecure side? I.e. a brute force approach will crack it pretty quickly...

What are you trying to achieve?

BTW: Change your UserName: posting your email address to public forums is an invitation to spam...

Posted 22-Mar-11 1:43am

OriginalGriff

Comments

Sergey Alexandrovich Kryukov 22-Mar-11 13:12pm

Agree with you, my 5.
--SA

#realJSOP 22-Mar-11 14:33pm

My solution is a better way to do it. Someone voted it a 1 with no explanation.

#realJSOP 22-Mar-11 15:06pm

Why he's creating 1000 passwords is beyond me, but I think he's just generating a temporary password and the user will have to change it the first time he logs on.

OriginalGriff 22-Mar-11 15:41pm

I think he is giving the user a choice! :laugh:
Why else put 1,000 random items in a ListView?
Maybe that's the test: one of these is your password: spot it and I'll let you log in...

#realJSOP 22-Mar-11 18:29pm

That would certainly be a novel approach. "Here's a crapload of possible passwords, pick yours from the unsorted list."

#realJSOP · Accepted Answer · 2011-03-22T01:42:00

Solution 1

Instead of going through all that, why don't you just create a GUID and give them a substring of the generated GUID?

C#

string password = Guid.NewGuid().ToString("N").Substring(5, 8);

No threading is needed.

EDIT ==============

The 1 vote on this answer is unjustified. My solution is a) Faster than the what was posted in the original question, and b) generates STRONGER random passwords because they may include alphabetic characters as well as numbers.

If you want proof of the randomness of using the Guid.NewGuid method, run this code in a WinForms app:

C#

private void CreateGuids()
{
    HashSet<string> hash = new HashSet<string>();
    for (int i = 0; i < 1000; i++)
    {
        hash.Add(Guid.NewGuid().ToString("N").Substring(5,8));
    }
    MessageBox.Show(string.Format("{0} unique passwords generated.", hash.Count));
}

There is no denying that this is a better solution than building a password one character at a time, and calling Random.Next for each character.

Posted 22-Mar-11 1:42am

#realJSOP

Updated 22-Mar-11 8:29am

v5

Comments

Christoph Keller 22-Mar-11 10:46am

SubString'ing a Guid would produce a lot of equal passwords, so this would not be a good solution (expecially if he want to generate 1000 PW's without any delay).

Just my 5 cents ;)

#realJSOP 22-Mar-11 14:12pm

You obviously have never played with the NewGuid() method. They're completely random. Run this code in a WinForms app and see what you get:
private void CreateGuids()
{
HashSet<string> hash = new HashSet<string>();
for (int i = 0; i < 1000; i++)
{
hash.Add(Guid.NewGuid().ToString("N").Substring(5,8));
}
MessageBox.Show(string.Format("{0} unique passwords generated.", hash.Count));
}

Just in case you're not familiar with the HashSet collection, it doesn't allow duplicate keys to be added. I ran this code several times, and ALWAYS got 1000 unique passwords.

Christoph Keller 22-Mar-11 16:43pm

I never said that a GUID is not unique, a GUID self is random for sure.

But what I mean is that if you Substring a Guid and shorten it, the possibility of duplicates is much higher.

O.k., I did not test your source (now I did and saw that no duplicates are generated), nor I did not see that you put it into a HashSet. Sorry for that. :)

I just saw the "Substring" and started to write ;)
So, sorry again!

#realJSOP 22-Mar-11 18:27pm

The use of the hashset was merely to prove that no duplicates were found. If the guy wanted to do it right, he'd create a password until he's got 1000 unique ones instead of merely trying 1000 times for 1000 unique ones.

OriginalGriff 22-Mar-11 15:39pm

JSOP is correct: Guids are completely random, and the phase space of a Guid is 2 to the power of 128. This equates to 3.4 times 10 to the power of 38. A three, followed by 38 zeros. That means that there is a 1 in 3*10^38 chance of two duplicates. Taking substrings of this does not reduce the randomness, it just reduces the phase space. The randomness of the Guid is likely to be higher than the randomness of the OP's original method, because the random number generator is not re-started each time - which is clock based, and in a sufficiently fast computer (or multithreaded environment with sufficient cores) can be persuaded to generate the same sequence.

Guid generation is quick as well: even on this not-very-quick-at-all PC, 1,000,000 guids takes less that 1/2 a second...

Christoph Keller 22-Mar-11 16:57pm

Please see my answer to John Simmons.

Thats completely true, I was focusing on the Substring of a Guid (which is less unique than a Guid self).

Sorry again for the confusion.

OriginalGriff 22-Mar-11 15:22pm

The univote is stupid: Guid is a good solution to password generation: I use it for all my personal passwords, keeping them in an encrypted file with a memorized strong password.
Compensated.

Christoph Keller 22-Mar-11 17:30pm

Compensated too, see my explanation before ;)