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c#random

How can I generate cryptographically strong random strings with a given length

I need to generate cryptographically strong random alphanumeric strings with a specified length, only using the following characters.

  • A-Z
  • a-z
  • 0-9

Is there a way to accomplish this in C#?

Solution

  • You can use class RandomNumberGenerator to generate cryptographically-secure random numbers to do this, for example:

    string allowed = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
int strlen = 10; // Or whatever
char[] randomChars = new char[strlen];

for (int i = 0; i < strlen; i++)
{
    randomChars[i] = allowed[RandomNumberGenerator.GetInt32(0, allowed.Length)];
}

string result = new string(randomChars);

Console.WriteLine(result);