Generate Random ascii string

GenerateUniqueString.cs

void Main()
{
    const string chars = "abcdefghijklmnopqrstuvwxyz0123456789";
    GenerateUniqueString(8, chars.ToCharArray()).Dump();
}

public static string GenerateUniqueString(int size, char[] chars)
{
    var data = new byte[4 * size];
    using var crypto = new RNGCryptoServiceProvider();
    crypto.GetBytes(data);

    var sb = new StringBuilder(size);
    for (var i = 0; i < size; i++)
    {
        var rnd = BitConverter.ToUInt32(data, i * 4);
        var idx = rnd % chars.Length;
        sb.Append(chars[idx]);
    }
    return sb.ToString();
}

sample

GenerateUniqueString(8, chars.ToCharArray())
-> vr8j41t1
-> pc55evum
-> hwnjuxvu
-> zwkcvohr

GenerateUniqueString(8, chars.ToCharArray())
-> ymfl6dosgu42ilxy9od5
-> zn6hdhz1rj7agidh5f3s
-> oxgkzf0v6yvos6drgel5
-> 5xuzbpe2544eldf39nyu