Generate Random Strings in C#

using System;
using System.Security.Cryptography;
using System.Text;

class RandomStringGenerator
{
    private const string Alphanumeric =
        "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    private const string HexChars = "0123456789abcdef";

    public static string GenerateRandomString(int length, string customChars = null)
    {
        string chars = customChars ?? Alphanumeric;

        using (var rng = RandomNumberGenerator.Create())
        {
            var result = new StringBuilder(length);
            byte[] randomBytes = new byte[length * 4];
            rng.GetBytes(randomBytes);

            for (int i = 0; i < length; i++)
            {
                uint randomValue = BitConverter.ToUInt32(randomBytes, i * 4);
                result.Append(chars[(int)(randomValue % chars.Length)]);
            }

            return result.ToString();
        }
    }

    static void Main()
    {
        // Generate a 16-character alphanumeric string
        string randomString = GenerateRandomString(16);
        Console.WriteLine(randomString);  // Example: aB3xY7mN2pQ9zR5t

        // Generate a 12-character hex string
        string hexString = GenerateRandomString(12, HexChars);
        Console.WriteLine(hexString);  // Example: a3f7b2e9c4d1

        // Generate a 10-character lowercase string
        string lowercaseString = GenerateRandomString(10, "abcdefghijklmnopqrstuvwxyz");
        Console.WriteLine(lowercaseString);  // Example: xmkpqrstuv
    }
}