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逆向工程一般说来就是在没有源代码的情况下，通过一定手段分析软件结构，挖掘出有用的信息或绕过软件自身的一些限制。目前对逆向的研究主要集中在Windows, Android，Mac和iOS这几个平台，各平台的发展也参差不齐。
#include <iostream>
using namespace std;
int max(int a, int b) {
// return a > b ? a : b;
if (a > b)
return a;
else
return b;
}
int main() {
int result = max(56, 32);
cout << "Result: " << result;
return 0;
}
未优化编译并逆向后的主要代码如下（在右侧增加了一些注释）:__Z3maxii: // max(int, int) ; have 8B on stack or two vars 00000001000010d0 push rbp ; XREF=0x1000000d0, _main+25 00000001000010d1 mov rbp, rsp 00000001000010d4 mov dword [ss:rbp+var_8], edi ; assign first var 00000001000010d7 mov dword [ss:rbp+var_C], esi ; assign second var 00000001000010da mov esi, dword [ss:rbp+var_8] ; stack: rbp, rsi 00000001000010dd cmp esi, dword [ss:rbp+var_C] 00000001000010e0 jle 0x1000010f1 ; >= 00000001000010e6 mov eax, dword [ss:rbp+var_8] 00000001000010e9 mov dword [ss:rbp+var_4], eax 00000001000010ec jmp 0x1000010f7 00000001000010f1 mov eax, dword [ss:rbp+var_C] ; XREF=__Z3maxii+16 00000001000010f4 mov dword [ss:rbp+var_4], eax 00000001000010f7 mov eax, dword [ss:rbp+var_4] ; XREF=__Z3maxii+28 00000001000010fa pop rbp 00000001000010fb ret _main: 0000000100001100 push rbp 0000000100001101 mov rbp, rsp 0000000100001104 sub rsp, 0x10 ; alloc some memory on stack 0000000100001108 mov edi, 0x38 ; argument #1 for method __Z3maxii 000000010000110d mov esi, 0x20 ; argument #2 for method __Z3maxii 0000000100001112 mov dword [ss:rbp+var_4], 0x0 ; init a var with 0 0000000100001119 call __Z3maxii ; max(int, int) ; result assigned to eax 000000010000111e mov rdi, qword [ds:imp___got___ZNSt3__14coutE] ; load object(cout) address 0000000100001125 lea rsi, qword [ds:0x100001f3c] ; "Result: " 000000010000112c mov dword [ss:rbp+var_8], eax ; max result assign to 2th var 000000010000112f call imp___stubs___ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc ; std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::operator<< <std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*) 0000000100001134 mov esi, dword [ss:rbp+var_8] 0000000100001137 mov rdi, rax ; eax != rdi, cout object has changed 000000010000113a call imp___stubs___ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEi ; std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(int) 000000010000113f xor esi, esi ; reset 0000000100001141 mov qword [ss:rbp+var_10], rax ; assign result(output stream) to last var 0000000100001145 mov eax, esi 0000000100001147 add rsp, 0x10 ; balance stack 000000010000114b pop rbp ; restore rbp 000000010000114c ret
理解上面的代码需要注意一些调用规定，上面的代码使用的fastcall调用约定。
本次破解使用的reveal版本是1.6.3(5790)，也是目前的最新版。由于编写一个注册机的难度较高，本次破解只是针对打补丁的方式，想挑战的话可以尝试编写一个注册机。
工欲善其事，必先利其器，mac下的破解工具主要有俩个，一个是hopper，另外一个是ida pro。本次破解使用hopper，这个软件更容易上手，注意需要装额外的调试工具，也可从官网下载到。
Your
free trial of Reveal has expire，也可能是其它的，取决于你的reveal是否过期Your
free trial of Reveal has expire，跳到引用该字符串的地方，这时会跳到[IBATrialModeReminderWindowController
trialExpiresTitle]·函数中间的某个地方，查找函数调用的对照，只要在根源处注释掉即可达到破解的目的IBATrialModeReminderWindowController，这是会调到[IBATrialModeReminderWindowController
controller]函数里面[IBATrialModeReminderWindowController
controller]的地方，会跟进这个函数[IBATrialModeReminderPresenter
showTrialModeSheetForWindow:][IBATrialModeReminderPresenter
presentTrialModeReminderIfNecessaryForWindow:]·这个函数，观察如下的代码，已经定位到我们想要的地方。000000010007f306 mov r14, rax 000000010007f309 mov rsi, qword [ds:0x1001b3150] ; @selector(shouldShowTrialModeSheet), argument "selector" for method imp___got__objc_msgSend 000000010007f310 mov rdi, rbx 000000010007f313 call qword [ds:imp___got__objc_msgSend] 000000010007f319 test al, al 000000010007f31b je 0x10007f330 000000010007f31d mov rsi, qword [ds:0x1001b3158] ; @selector(showTrialModeSheetForWindow:), argument "selector" for method imp___got__objc_msgSend 000000010007f324 mov rdi, rbx ; argument "instance" for method imp___got__objc_msgSend 000000010007f327 mov rdx, r14 000000010007f32a call qword [ds:imp___got__objc_msgSend] 000000010007f330 mov rdi, r14 ; argument "instance" for method imp___got__objc_release, XREF=-[IBATrialModeReminderPresenter presentTrialModeReminderIfNecessaryForWindow:]+40 000000010007f333 pop rbx 000000010007f334 pop r14 000000010007f336 pop rbp 000000010007f337 jmp qword [ds:imp___got__objc_release]
je
0x10007f330，如果不跳转回执行下面的代码就会显示提示对话框，因此把条件取反，或者无条件跳转改成jmp
je 0x10007f330即可
如果觉得上面步骤繁琐的话，其实还有更简单的方法，按照一般的编程思维，一般都会写一个shouldShow…的方法来显示提示对话框，所以直接搜索字符串·shouldShow·，调到这个函数[IBATrialModeReminderPresenter
shouldShowTrialModeSheet]，这个函数的代码如下：
-[IBATrialModeReminderPresenter shouldShowTrialModeSheet]: 000000010007fde3 push rbp ; Objective C Implementation defined at 0x10018dc40 (instance) ... ... 000000010007fdf1 mov r15, rdi 000000010007fdf4 call sub_10007e91a 000000010007fdf9 test al, al 000000010007fdfb jne 0x10007fe06 000000010007fdfd call sub_10007e95e 000000010007fe02 test al, al 000000010007fe04 je 0x10007fe1a 000000010007fe06 xor ebx, ebx ; XREF=-[IBATrialModeReminderPresenter shouldShowTrialModeSheet]+24 000000010007fe08 movzx eax, bl ... ... 000000010007fe19 ret觉得汇编不好理解不直观的话,可以来点黑科技，看自动生成的高级语言代码：
char -[IBATrialModeReminderPresenter shouldShowTrialModeSheet](void * self, void * _cmd) {
r15 = self;
if ((sub_10007e91a() != 0x0) && (sub_10007e95e() == 0x0)) {
r14 = [[NSDate date] retain];
r13 = [[[r15 class] lastPresentationDateTime] retain];
[r13 release];
rbx = 0x1;
if (r13 != 0x0) {
[r14 timeIntervalSinceReferenceDate];
var_30 = intrinsic_movsd(var_30, xmm0);
...
...
COND = xmm1 > 0x0;
rbx = COND ? 0x1 : 0x0;
[r13 release];
}
[r14 release];
}
else {
rbx = 0x0;
}
rax = rbx & 0xff;
return rax;
}
仔细分析代码，发现两处关键代码：000000010007fdfb jne 0x10007fe06 000000010007fe04 je 0x10007fe1a
所以只需要把000000010007fdfb地址处的代码改为jmp
0x10007fe1a即可
以上的操作都是在内存中修改的，关闭后重新打开还是无法使用，执行File -> Produce New Executable file, 这是会提示你签名无效，是否移除签名，选择否，(如果选择是的话，每次启动都会有个提示很烦人的),替换原来的可执行文件，重新启动Reveal,会提示This
copy of Reveal is damaged，解决方法同上，不在这里赘述。
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原文地址：http://blog.csdn.net/wp1603710463/article/details/50984147
