Random Id Generator

rndidgen.cs

class IdGenerater
{
	private string[] charss = //generated by RandChars
	{
		"47eRaiGQZHjXPnxh2dfUYbDmN986ycTSvkLuKoJtApWqEMwzFCVr3gs5B",
		"6BD28rJaZzqTEjVQsUvNMLfimWG5k94gbK3wyhXPSpxucotHeFCYAdR7n",
		"RijAmWYBHtkwJP8K4bgMN5GDFX6zLZsqUhueyEVpdxSa7ocQvTnr32fC9",
		"xeuNs75AhUSFkM4TmCZgEtKHDX6QjiG9RvL8opqwadJBcyPYrb3WnzV2f",
		"XNQisGdLDSU4Wx2V5PczY8MahpHnuy6j3fvFEAqrTJmRgZk9btw7KBoeC",
		"qTmR5btpxP8wGEa6i4zVZurJg7hKysdoMnDFUeX3SCWH2kjc9QfBYNLAv",
	};
	private const int CHARS_LENGTH = 57;
	private int[] indexes = new int[6];
	private char[] chars = new char[6];

	public int[] Generate(int id)
	{
		int p = 0;

		if (id < 0)
			throw new ArgumentOutOfRangeException("id");

		while (id >= CHARS_LENGTH)
		{
			int rem = id % CHARS_LENGTH;
			indexes[p++] = rem;
			id = (id - rem) / CHARS_LENGTH;
		}
		indexes[p] = id;
		return indexes;
	}

	public string GenerateString(int id)
	{
		var indexes = Generate(id);
		int index = 0;

		//TODO add proof: the random indexes are still unique
		for (int i = 0; i < indexes.Length; ++i)
		{
			index += indexes[i]; //higher index is also random
			chars[i] = charss[i][index % CHARS_LENGTH];
		}

		return new string(chars);
	}
}

//Generate random character sequence
class RandChars
{
	const string chars = "ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz23456789"; //57 chars
	private Random _rnd = new Random();

	public void Generate()
	{
		var charArr = chars.ToCharArray();

		Comparison<char> comparer = RandomComparer;
		for (int i = 0; i < 6; ++i)
		{
			Array.Sort(charArr, comparer);
			Console.WriteLine(new string(charArr));
		}
	}

	private int RandomComparer(char c1, char c2)
	{
		return _rnd.Next().CompareTo(_rnd.Next());
	}
}