using namespace std;
#include <string>
#include <iostream>
#include <vector>
unsigned char returnnextbyte(unsigned int b)
{
int U4, L4;
int Yl, Yh;
int total;
U4 = (b & 0xF0) >> 4;
L4 = b & 0x0F;
Yl = (L4 * 3) % 16;
Yh = ( (3 * U4) + ((L4 * 5) % 16) + (int)((double)L4 / 5.01)) % 16;
total = (Yh << 4) + Yl;
return (unsigned char)total;
}
int main(int argc, char* argv[])
{
unsigned int i, x;
unsigned int b;
unsigned char nextbyte;
string cmd;
vector <unsigned int> myints;
if (argc == 1)
{
cout << "Usage: " << endl;
cout << "decoder b1 b2 ... bn" << endl;
cout << "b1 MUST correspond to ascii value 100" << endl;
return 0;
}
else
{
x = strtol(argv[1], NULL, 16);
b = (unsigned char)x ^ (unsigned char)100; // XOR
nextbyte = returnnextbyte(b);
myints.push_back(100);
for (i = 2; i < argc; i++)
{
x = strtol(argv[i], NULL, 16);
b = (unsigned char)x ^ (unsigned char)nextbyte;
myints.push_back(b);
nextbyte = returnnextbyte(nextbyte);
}
cout << endl;
}
for (i = 0; i < myints.size(); i++)
cout << myints[i] << " ";
cout << endl;
// myints holds the decrypted command
return 0;
}