creates a hash of a file from a filename

hash file

using (MD5 md5 = MD5.Create())
{
    using (FileStream stream = File.OpenRead(filename))
    {
        byte[] bytes = md5.ComputeHash(stream);
        bool uppercase = false;

        StringBuilder result = new StringBuilder(bytes.Length * 2);

        for (int i = 0; i < bytes.Length; i++)
        {
            result.Append(bytes[i].ToString(uppercase ? "X2" : "x2"));
        }

        return result.ToString();
    }
}