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| #include <stdio.h>
#include <string.h>
#include <stdint.h>
#define MX (((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4)) ^ ((sum ^ y) + (key[(p & 3) ^ e] ^ z)))
typedef unsigned char BYTE;
unsigned char aLaughterIsPois[] = "Laughter_is_poison_to_fear";
unsigned char xor_xtea_num[48] = {0xDA, 0x30, 0x23, 0xE3, 0xDC, 0x39, 0x82, 0x60, 0xA5, 0x44,
0x68, 0xC2, 0x43, 0x7A, 0xBB, 0xE4, 0x50, 0xE1, 0x02, 0xC2,
0x81, 0x59, 0xEA, 0x1E, 0xC6, 0x8B, 0x71, 0x38, 0x27, 0x83,
0x94, 0xD8, 0xF4, 0x8D, 0x1A, 0x2A, 0x56, 0x8A, 0x4A, 0xD4,
0x54, 0xDC, 0x24, 0x3F, 0xB9, 0xED, 0x7B, 0x9A};
unsigned char xor_xxtea_num[48] = {0x8f, 0x6c, 0xa6, 0x3f, 0x94, 0x3d, 0xf5, 0xd9, 0x36, 0x66, 0x51, 0xd7, 0x66,
0x2f, 0xb3, 0x8f, 0xc0, 0x61, 0x9e, 0xce, 0xe9, 0xd7, 0xe1, 0xbf, 0x13, 0x14,
0x16, 0x14, 0xc2, 0xe7, 0xc3, 0x3a, 0x7f, 0x94, 0xa1, 0xe7, 0x24, 0x0e, 0xa7,
0x5c, 0xd3, 0x77, 0xfe, 0x4f, 0x11, 0xdc, 0x69, 0x23};
void xtea_decrypt(unsigned char *data, size_t length)
{
for (int i = 0; i < 48; i++)
{
data[i] ^= xor_xtea_num[i];
}
unsigned int *v = (unsigned int *)data;
unsigned char key_xtea[] = "{you_find_it_!?}";
unsigned int *v8 = (unsigned int *)key_xtea;
for (int l = 0; l < 12; l += 2)
{
unsigned int v6 = v[l], v5 = v[l + 1], v4 = 0;
unsigned int delta = 0x61C88647;
v4 = -1 * 32 * delta;
for (int i = 0; i < 32; i++)
{
v5 -= (v8[(v4 >> 11) & 3] + v4) ^ (((v6 >> 5) ^ (16 * v6)) + v6);
v4 += delta;
v6 -= (v8[v4 & 3] + v4) ^ (((v5 >> 5) ^ (16 * v5)) + v5);
}
v[l] = v6;
v[l + 1] = v5;
}
for (int i = 0; i < 48; i++)
{
data[i] ^= aLaughterIsPois[i % 26];
}
}
void xxtea_decrypt(uint8_t *data)
{
for (int i = 0; i < 48; i++)
{
data[i] ^= xor_xxtea_num[i];
}
int n = -12;
uint32_t *v = (uint32_t *)data;
unsigned char *key_xxtea = "{What_is_this_?}";
uint32_t *key = (unsigned int *)key_xxtea;
uint32_t y, z, sum;
unsigned p, rounds, e;
unsigned int delta = 0x11451419;
if (n > 1)
{
rounds = 6 + 52 / n;
sum = 0;
z = v[n - 1];
do
{
sum += delta;
e = (sum >> 2) & 3;
for (p = 0; p < n - 1; p++)
{
y = v[p + 1];
z = v[p] += MX;
}
y = v[0];
z = v[n - 1] += MX;
} while (--rounds);
}
else if (n < -1)
{
n = -n;
rounds = 6 + 52 / n;
sum = rounds * delta;
y = v[0];
do
{
e = (sum >> 2) & 3;
for (p = n - 1; p > 0; p--)
{
z = v[p - 1];
y = v[p] -= MX;
}
z = v[n - 1];
y = v[0] -= MX;
sum -= delta;
} while (--rounds);
}
}
int main()
{
unsigned char data[48] = {0x18, 0x09, 0x1C, 0x14, 0x37, 0x1D, 0x16, 0x2D, 0x3C, 0x05,
0x16, 0x3E, 0x02, 0x03, 0x10, 0x2C, 0x0E, 0x31, 0x39, 0x15,
0x04, 0x3A, 0x39, 0x03, 0x0D, 0x13, 0x2B, 0x3E, 0x06, 0x08,
0x37, 0x00, 0x17, 0x0B, 0x00, 0x1D, 0x1C, 0x00, 0x16, 0x06,
0x07, 0x17, 0x30, 0x03, 0x30, 0x06, 0x0A, 0x71};
xxtea_decrypt(data);
xtea_decrypt(data, 48);
for (int i = 0; i < 48; i++)
{
printf("%c", data[i]);
}
}
#DASCTF{You_come_to_me_better_than_all_the_good.}
|
