BiW Reversing - Bruteforcing Zeph's crackme

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Bruteforcing Zeph's crackme

Authored by: bluffer on Tuesday, April 19 2005 @ 07:02 PM CEST

ah thanks for mention Boro :)

hope i could add a few comments to this tut as you know i was loooking for a sppedier way that eliminates the twenty minutes :)

i removed the wsprintf and coded an inline convertor which reduced the time to about 10 minutes
and i came to #win32asm on efnet to bug some of them to find some more improvements :) parabytes there suggested some improvements in the convertor like stosd instead of stosb which were marginal improvemnts then scali took an interest in the code and coded a c++ and applied pentium optimization switches and it drastically reduced the time to about one minute :) iam pasting below the c++ code that was from scali :)


#include <stdio.h>

int main(void)
{
    char* table = "0123456789ABCDEF";
    char key[] = "F000FFF0";

    for (unsigned int a = 0; a < 16; a++)
    {
        key[0] = table[a];

        for (unsigned int b = 0; b < 16; b++)
        {
            key[1] = table[b];

            for (unsigned int c = 0; c < 16; c++)
            {
                key[2] = table[c];

                for (unsigned int d = 0; d < 16; d++)
                {
                    key[3] = table[d];

                    for (unsigned int e = 0; e < 16; e++)
                    {
                        key[4] = table[e];

                        for (unsigned int f = 0; f < 16; f++)
                        {
                            key[5] = table[f];

                            for (unsigned int g = 0; g < 16; g++)
                            {
                                key[6] = table[g];

                                for (unsigned int h = 0; h < 16; h++)
                                {
                                    key[7] = table[h];

                                    unsigned int hash = 0x811C9DC5;

                                    for (unsigned int i = 0; i < 8; i++)
                                    {
                                        hash ^= (unsigned char)key[i];
                                        hash *= 0x1000193;
                                    }

                                    if (hash == 0xA7BA8755)
                                        goto end;
                                }
                            }
                        }
                    }
                }
            }
        }
    }
end:
    printf( "%s\n", key );

    return 0;
}

commadline for gpp
g++ -Wall -O3 bruter.c -o bruter
[bluffer@]$ ./bruter F000FFF0 Bruting time ->69sec

it was fun doing the brute and speed optimizing it :)
and hey detten nice site layout :)
greets to all