using System;using System;

public class Program

{

    public static Int32 transform(int data, int[] sec) {

        Int32 result = ((data % sec[0]) * sec[2]) - ((data / sec[0]) * sec[1]);

        if (result < 0)

            result += (sec[0] * sec[2]) + sec[1];

        return result;

    }

    public static string getKey(string seedTXT, string appKeyTXT) {

        Int32 result;

        string[] seed = {seedTXT.Substring(0,2), seedTXT.Substring(2,2), seedTXT.Substring(4,2), seedTXT.Substring(6,2)};

        string[] appKey = {appKeyTXT.Substring(0,2), appKeyTXT.Substring(2,2)};

​

        // Hardcoded secrets

        int[] sec_1 = {0xB2, 0x3F, 0xAA};

        int[] sec_2 = {0xB1, 0x02, 0xAB};

        // Compute each 16b part of the response, with the twist, and return it

        Int32 res_msb = transform(Int16.Parse(appKey[0]+appKey[1], System.Globalization.NumberStyles.HexNumber), sec_1) | transform(Int16.Parse(seed[0]+seed[3], System.Globalization.NumberStyles.HexNumber), sec_2);

        Int32 res_lsb = transform(Int16.Parse(seed[1]+seed[2], System.Globalization.NumberStyles.HexNumber), sec_1) | transform(res_msb, sec_2);

        result = (res_msb << 16) | res_lsb;

        return result.ToString("X8"); 

    }

    public static void Main()

    {

        Console.WriteLine(getKey("A954AA55", "D91C"));

    }

}