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I'm learning for the university and have to do a Mifare Classic replay attack. I don't really know how to do that and hope some of you can help me at least a bit.

The goal is to get the number of iterations after the start of the random number generator of the valid session.

Here is the information I got:

Random Number Zx:
2225499778

Seed:
1735622233


Polynomial:
x^24 + x^23 + x^22 + x^21 + x^19 + x^18 + x^17 + x^13 + x^5 + x^4 + x^3 + x^2 + 1

I have already implemented a basic LFSR in C but don't know what to do next:

#include <sys/types.h>
#include <stdio.h>

#define INITIAL 67737E59
int main(void) {
    __int32 reg = INITIAL;
    __int32 bit;
    do {
        bit = (reg & 0x0001) ^
                ((reg & 0x0004) >> 2) ^
                ((reg & 0x0008) >> 3) ^
                ((reg & 0x0020) >> 5);
        reg = (reg >> 1) | (bit << 23);
        printf("%i", bit);
    } while (reg != INITIAL);


return 0;



}

0 Answers0