rctf2018 babyre writeup

#include <stdio.h>
#include <string.h>
#include <stdint.h>
uint32_t foo(uint32_t a1, uint64_t a2) // sub_804868B
{
    int j;
    uint64_t v5;
    uint32_t in;
    in = a1;
    for (j = 0; j <= 527; ++j)
    {
        v5 = a2 >> (j & 0x1F);
        if (j & 0x20)
            v5 = v5 >> 32;           //高低位转换 
        in = (in >> 1) ^ ((v5 ^ in ^ (in >> 16) ^ (0x5C743A2E >> (((in >> 1) & 1)
            + 2
            * (2
                * (((in >> 20) & 1)
                    + 2* (2 * (in >> 31) + ((in >> 26) & 1)))
                + ((in >> 9) & 1))))) << 31);
    }
    return in;
}

int main()
{
    uint32_t data[30] = // out
    {
        0xB80C91FE,0x70573EFE,
        0xBEED92AE,0x7F7A8193,
        0x7390C17B,0x90347C6C,
        0xAA7A15DF,0xAA7A15DF,
        0x526BA076,0x153F1A32,
        0x545C15AD,0x7D8AA463,
        0x526BA076,0xFBCB7AA0,
        0x7D8AA463,0x9C513266,
        0x526BA076,0x6D7DF3E1,
        0xAA7A15DF,0x9C513266,
        0x1EDC3864,0x9323BC07,
        0x7D8AA463,0xFBCB7AA0,
        0x153F1A32,0x526BA076,
        0xF5650025,0xAA7A15DF,
        0x1EDC3864,0xB13AD888
    };
    int i;
    uint32_t j;
    for (i = 0; i < 30; i++)
        for (j = 0x20; j < 0x7F; j++)                    //0x20F/4=0x7F 
            if (foo(j, 0x1D082C23A72BE4C1) == data[i])   //互换，合并 
                printf("%c", j);
    printf("n");
    return 0;
}