【破文标题】一个KeygenMe的算法分析及算法注册机
【破文作者】zaas
【破解工具】OllyICE
【破解平台】WinXP
【破解声明】我是一只小菜鸟，偶得一点心得，愿与大家分享
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【破解内容】
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很久没有玩过什么软件了。今天闲暇，翻了翻Tuts4U，发现一个新的KeygenMe，玩玩。
首先查壳：peid显示是ASPack 2.12 -> Alexey Solodovnikov。
OD看了看，原来是修改了特征码假冒的。。。
00401414 > $ 60 pushad
00401415 . E8 03000000 call 0040141D
0040141A E9 db E9
0040141B EB db EB
0040141C 04 db 04
0040141D /$ 5D pop ebp
0040141E |. 45 inc ebp
0040141F |. 55 push ebp
00401420 \. C3 retn
00401421 E8 db E8
00401422 01 db 01
00401423 00 db 00
00401424 00 db 00
00401425 . 00EB add bl, ch
0040135B . 68 95010000 push 0x195 ; /ControlID = 195 (405.)
00401360 . FF75 08 push dword ptr [ebp+0x8] ; |hWnd
00401363 . E8 16030000 call <jmp.&user32.GetDlgItem> ; \GetDlgItem得到注册名editbox的hWnd
00401368 . A3 90344000 mov dword ptr [0x403490], eax
0040136D . 16 push ss
0040136E . 81C3 8EA80800 add ebx, 0x8A88E
00401374 . 42 inc edx
00401375 . 83F2 3C xor edx, 0x3C
00401378 . 83E2 00 and edx, 0x0
0040137B . 17 pop ss
0040137C . 9C pushfd
0040137D . 58 pop eax ; 无用代码
0040137E . 25 00010000 and eax, 0x100
00401383 . 0BC0 or eax, eax
00401385 . F64424 01 01 test byte ptr [esp+0x1], 0x1 ; 判断是否成功获取注册名editbox的hWnd
0040138A . 0F85 D8010000 jnz 00401568
00401390 . E8 A4020000 call 00401639 ; 动态加载SendMessageA
00401395 . 68 9C344000 push 0040349C ; 注册名的保存地址Buffer
0040139A . 6A 15 push 0x15 ; len
0040139C . 6A 0D push 0xD ; WM_GETTEXT
0040139E . FF35 90344000 push dword ptr [0x403490] ; hWnd
004013A4 . FFD0 call eax ; SendMessageA
004013A6 . 8BD0 mov edx, eax ; eax返回获取字符串长度 len
004013A6 . 8BD0 mov edx, eax ; eax返回获取字符串长度 len
004013A8 . 42 inc edx ; len+1
004013A9 . C1E2 03 shl edx, 0x3 ; (len+1)<<3
004013AC . BE 80000000 mov esi, 0x80
004013B1 . 8D3C32 lea edi, dword ptr [edx+esi] ; 80+(len+1)<<3
004013B4 . 69D7 E6010000 imul edx, edi, 0x1E6 ; (80+(len+1)<<3)*1E6
004013BA . 83E6 00 and esi, 0x0
004013BD . 87F2 xchg edx, esi
004013BF . 33D2 xor edx, edx
004013C1 . 81FE 505D0100 cmp esi, 0x15D50 ; (80+(len+1)<<3)*1E6 >= 0x15D50
004013C7 . 73 05 jnb short 004013CE ; 不小于跳
004013C9 . E9 9A010000 jmp 00401568
004013CE > 83F8 0C cmp eax, 0xC ; 最多0xC位
004013D1 . 0F87 91010000 ja 00401568
004013F1 . B8 9C344000 mov eax, 0040349C
004013F6 . EB 06 jmp short 004013FE
004013F8 > 8030 4E xor byte ptr [eax], 0x4E ; ^=4E
004013FB . D020 shl byte ptr [eax], 1 ; (char ^4E)<<1
004013FD . 40 inc eax
004013FE > 8038 00 cmp byte ptr [eax], 0x0 ; 检测字符串是否为空
00401401 .^ 75 F5 jnz short 004013F8
for (int i = 0;i <len;i++)
{
*(str + i) ^= 0x4E;
*(str + i) <<= 1;
}
004011E7 /$ 55 push ebp
004011E8 |. 8BEC mov ebp, esp
004011EA |. 53 push ebx
004011EB |. 56 push esi
004011EC |. 33C0 xor eax, eax
004011EE |. 40 inc eax ; int eax =1
004011EF |. 33DB xor ebx, ebx ; int ebx =0
004011F1 |. 8B75 08 mov esi, dword ptr [ebp+0x8] ; str2
004011F4 |> 837D 0C 00 /cmp dword ptr [ebp+0xC], 0x0
004011F8 |. 74 3B |je short 00401235
004011FA |. 817D 0C B0150>|cmp dword ptr [ebp+0xC], 0x15B0
00401201 |. 77 05 |ja short 00401208
00401203 |. 8B55 0C |mov edx, dword ptr [ebp+0xC]
00401206 |. EB 05 |jmp short 0040120D
00401208 |> BA B0150000 |mov edx, 0x15B0
0040120D |> 2955 0C |sub dword ptr [ebp+0xC], edx
00401210 |> 85D2 |/test edx, edx
00401212 |. 74 0C ||je short 00401220
00401214 |. 4A ||dec edx
00401215 |. 33C9 ||xor ecx, ecx ; int i=0
00401217 |. 8A0E ||mov cl, byte ptr [esi] ; str[i]
00401219 |. 03C1 ||add eax, ecx ; eax += str[i]
0040121B |. 46 ||inc esi ; str++
0040121C |. 03D8 ||add ebx, eax ; ebx += eax
0040121E |.^ EB F0 |\jmp short 00401210
00401220 |> B9 F1FF0000 |mov ecx, 0xFFF1
00401225 |. 33D2 |xor edx, edx
00401227 |. F7F1 |div ecx
00401229 |. 52 |push edx ; eax %= FFF1
0040122A |. 8BC3 |mov eax, ebx
0040122C |. 33D2 |xor edx, edx
0040122E |. F7F1 |div ecx
00401230 |. 8BDA |mov ebx, edx ; ebx %= FFF1
00401232 |. 58 |pop eax
00401233 |.^ EB BF \jmp short 004011F4
00401235 |> C1E3 10 shl ebx, 0x10 ; eax =ebx <<10 +eax
00401238 |. 0BC3 or eax, ebx
0040123A |. 5E pop esi
0040123B |. 5B pop ebx
0040123C |. C9 leave
0040123D \. C2 0800 retn 0x8
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