random password generator

[nicklieb]

I found this code

    public static string CreateRandomPassword(int PasswordLength)
    {
        string _allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ0123456789!@$?";
        Byte[] randomBytes = new Byte[PasswordLength];
        char[] chars = new char[PasswordLength];
        int allowedCharCount = _allowedChars.Length;

        for (int i = 0; i < PasswordLength; i++)
        {
            chars[i] = _allowedChars[(int)randomBytes[i] % allowedCharCount];
        }

        return new string(chars);
    }

but for reason it keeps returning aaaaaaa.

The bit that I don't understand is :

chars[i] = _allowedChars[(int)randomBytes[i] % allowedCharCount];

now the modulus will change on each iteration, but why is it still returning the frist letting of the string?

thanks in advance

 

[cappmgr]

I believe (int)randomBytes will always be 0.
0 mod n = 0.
Marty

 

[chiph]

Yes, there's nothing in that code to create random anything.

Take a look at the System.Security.Cryptography namespace. There's a class in there call RNGCryptoServiceProvider, which is a strong random-number generator. You'd use it like this:

byte[] randomBytes = new byte[100];
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
rng.GetBytes(randomBytes);

Chip H.


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