CODEWITHSUNDEEP
c#
user2254436
user2254436

Reputation: 543

Get the same password for the same string

I'm looking for a code to generate the same password for the string presented. Like a challenge and response.

I want to do a very simple winform based on c# in which I will enter a name and get a random string that represent the password for this name.

For example: I will enter "Bob", click on "Generate password" and get for example "hakdn11jhfh32" (something random), then for the name "David" I'll get another password, but when I'll enter "Bob" again I will get the same password for Bob before ("hakdn11jhfh32").

Is there an easy way?

I actually thought of just giving some characters for one character (like: a=8j2, 5=j1mm.....) and then just do a replace for every name given. But I'm hoping that there is something easier and more automatic.

Upvotes: 0

Views: 103

Answers (2)

Cydrick Trudel
Cydrick Trudel

Reputation: 10497

What you are describing is hashing. Here's an official article:

http://msdn.microsoft.com/en-us/library/aa545602%28v=cs.70%29.aspx

Also, this article provides a small piece of code:

http://www.techpowerup.com/forums/threads/c-hash-encryption-example.62293/

public string GeneratePasswordHash(string thisPassword)
{
    MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
    byte[] tmpSource;
    byte[] tmpHash

    tmpSource = ASCIIEncoding.ASCII.GetBytes(thisPassword); // Turn password into byte array
    tmpHash = md5.ComputeHash(tmpSource);

    StringBuilder sOuput = new StringBuilder(tmpHash.Length);
    for (int i = 0; i < tmpHash.Lenth; i++)
    {
        sOutput.Append(tmpHash[i].ToString(“X2”));  // X2 formats to hexadecimal
    }
    return sOutput.ToString();
}

Upvotes: 3

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726529

You can use the property of pseudo-random number generator that lets you seed its sequence. Make a random number generator like this:

String name = "Bob";
Random rnd = new Random(name.hashCode());

Now you can generate a string of random character codes using the rnd.nextInt(numChars), where numChars is the number of characters that can appear in the password:

StringBuilder pwd = new StringBuilder();
int numCharInPassword = 8;
String legalChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*/{}[]\|";:<>()+=";
for (int i = 0 ; i != numCharInPassword ; i++) {
    pwd.append(legalChars.charAt(rnd.nextInt(legalChars.length())));
}

This guarantees that starting with the same name and using the same pre-set password will produce the same password. Sometimes, a different name could produce the same password, too, but that is unlikely.

Upvotes: 1

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