Generate random characters

public string GetRandomPasswordUsingGUID(int length)
        {
            // Get the GUID
            string guidResult = System.Guid.NewGuid().ToString();
            // Remove the hyphens
            guidResult = guidResult.Replace("-", string.Empty);
            // Make sure length is valid
            if (length <= 0 || length > guidResult.Length)
                throw new ArgumentException("Length must be between 1 and " + guidResult.Length);
            // Return the first length bytes
            return guidResult.Substring(0, length);
        }