Takes a hex string of arbitrary value and turns it into a binary string. Works with hex strings that would overflow number types (e.g. EPC codes).

hexToBinary.cs

/*  Creates a binary string from a arbitrary long hex string 
    Taken from https://github.com/dannyhaak/TagDataTranslation/
*/
private static string HexToBinary(string hex) 
{
    StringBuilder binary = new StringBuilder();
    for (int i = 0; i < hex.Length; i++) 
    {
        int integer = Convert.ToInt16(hex.Substring(i, 1), 16);
        binary.Append(Convert.ToString(integer, 2).PadLeft(4, '0'));
    }
    return binary.ToString();
}