逆了一遍，要达到腾讯要求的高校生水准还是不容易。。
#include <stdio.h>
#include <windows.h>
char sample_str[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789@%";
int Get_Index_in_sample(UCHAR ch)
{
char *p = (char*)memchr(sample_str, ch, sizeof(sample_str)-1);
if (p)
return (int)(p - sample_str);
else
return -1;
}
int UserName(PLONG UserNameArray)
{
char chUserName[] = "zxxttrrun";
ULONG UserNameLen = (ULONG)strlen(chUserName);
char tmp[25] = {0};
ULONG *v7;
ULONG i;
if ( (unsigned int)(UserNameLen - 6) > 0xE )
return -1;
for (i = 0; i < 16; i++)
{
v7 = (ULONG*)&tmp[i];
*v7 += UserNameLen * (i + 20160126) * chUserName[i % UserNameLen];
}
for ( i = 0; i < 20; i += 4 )
{
UserNameArray[i/4] = (*(LONG *)&tmp[i]) / 10;
}
return 0;
}
int Password(PULONG PasswordArray)
{
char PasswordBuf[100] = "JVeFMIdiy5HLoQcSzMzMzMzMzMz";
ULONG PasswordLen = 27;
ULONG tmpDWORD;
PUCHAR p = (PUCHAR)&tmpDWORD;
ULONG i;
ULONG j;
UCHAR tmp[25] = {0};
PUCHAR p1 = tmp;
for (i = 0, j = 0; i < PasswordLen; i++)
{
char ch = PasswordBuf[i];
if ( !isalnum(ch) && ch != '@' && ch != '%' )
break;
p[i%4] = ch;
if(j++ == 3)
{
for ( j = 0; j < 4; j++ )
{
p[j] = Get_Index_in_sample(p[j]);
}
*p1++ = (p[0]<<2) + ((p[1] >> 4) & 3);
*p1++ = (p[1] << 4) ^ ((p[2] >> 2) & 0xF);
*p1++ = (p[2] << 6) + p[3];
j = 0;
}
}
if (j)
{
memset((char *)&tmpDWORD + j, 0, 4 - j);
for ( j = 0; j < 4; j++ )
{
p[j] = Get_Index_in_sample(p[j]);
}
*p1++ = (p[0]<<2) + ((p[1] >> 4) & 3);
*p1++ = (p[1] << 4) ^ ((p[2] >> 2) & 0xF);
*p1++ = (p[2] << 6) + p[3];
}
for ( i = 0; i < 20; i += 4 )
{
PasswordArray[i/4] = *(ULONG *)&tmp[i];
}
return 0;
}
int main()
{
LONG U[5]; // 逆向过程是算数右移，所以必须是有符号数
ULONG P[5];
UserName(U);
Password(P);
if ( P[4] + U[0] == P[2] &&
P[2] + U[1] == P[4] * 2 &&
P[3] + U[2] == P[0] &&
P[0] + U[3] == P[3] * 2 &&
P[1] + U[4] == U[2] * 3)
{
printf("注册成功~\n");
}
else
printf("注册失败!\n");
return 0;
}
[课程]Android-CTF解题方法汇总！
