GFSJ0874-【666】
xor
main
int __fastcall main(int argc, const char **argv, const char **envp)
{
char s[240]; // [rsp+0h] [rbp-1E0h] BYREF
char v5[240]; // [rsp+F0h] [rbp-F0h] BYREF
memset(s, 0, 0x1Eu);
printf("Please Input Key: ");
__isoc99_scanf("%s", v5);
encode(v5, (__int64)s);
if ( strlen(v5) == key )
{
if ( !strcmp(s, enflag) )
puts("You are Right");
else
puts("flag{This_1s_f4cker_flag}");
}
return 0;
}
加密函数 简单异或
int __fastcall encode(const char *a1, __int64 a2)
{
_BYTE v3[104]; // [rsp+10h] [rbp-70h]
int v4; // [rsp+78h] [rbp-8h]
int i; // [rsp+7Ch] [rbp-4h]
i = 0;
v4 = 0;
if ( strlen(a1) != key )
return puts("Your Length is Wrong");
for ( i = 0; i < key; i += 3 )
{
v3[i + 64] = key ^ (a1[i] + 6);
v3[i + 33] = (a1[i + 1] - 6) ^ key;
v3[i + 2] = a1[i + 2] ^ 6 ^ key;
*(_BYTE *)(a2 + i) = v3[i + 64];
*(_BYTE *)(a2 + i + 1LL) = v3[i + 33];
*(_BYTE *)(a2 + i + 2LL) = v3[i + 2];
}
return a2;
}
数据
key = 0x12
enflag = 'izwhroz""w"v.K".Ni'
exp
enflag = b'izwhroz""w"v.K".Ni'
flag=''
for i in range(0,18,3):
flag+=chr((18^enflag[i])-6)
flag+=chr((18^enflag[i+1])+6)
flag+=chr(18^enflag[i+2]^6)
print(flag)
flag
unctf{b66_6b6_66b}
一把梭
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