Hot<SPAN CLASS="pediy">keyMaster算法分析----菜鸟级 (4千字)
软件名称:HotkeyMaster下载地址:http://www.core-project.com/hotkeymaster/HotkeyMaster.exe
软件介绍:如软件名.今天在ROR论坛看到有网友原创了该软件的使用教程,喈软件如痴的我自然不肯放过.下载回来后发现确实顺手,可需要注册----不爽.
使用工具:FI,W32DASM,OllyDbg
破解过程:
1.使用FI查看软件是否加壳和所使用的编程语言
2.万幸,软件并未加壳
3.运行W32DASM,查找软件注册失败后提示的出错信息.
启动OllyDbg,F3载入Hotkey Master.利用我们在W32DASM中分析找到的关键CALL-004144C1设断.
或者点击鼠标右键"Search for"->"All referenced text strings"查找"The key you entered is not
correct."向上查找同样可以找到断点
:004144C1 E83FE7FFFF call 00412C05
----嗯,就是你了!!!进入分析!!
:004144C6 83C410 add esp, 00000010
:004144C9 3BC7 cmp eax, edi
:004144CB 7545 jne 00414512
:004144CD 8D85E0FEFFFF lea eax, dword ptr [ebp+FFFFFEE0]
:004144D3 50 push eax
:004144D4 FF35949E4200 push dword ptr [00429E94]
:004144DA FF35809E4200 push dword ptr [00429E80]
:004144E0 E835BCFFFF call 0041011A
:004144E5 8D45E0 lea eax, dword ptr [ebp-20]
:004144E8 50 push eax
:004144E9 FF35989E4200 push dword ptr [00429E98]
:004144EF FF35809E4200 push dword ptr [00429E80]
:004144F5 E820BCFFFF call 0041011A
:004144FA 83C418 add esp, 00000018
:004144FD C605F8B4430001 mov byte ptr [0043B4F8], 01
:00414504 56 push esi
:00414505 FF35749E4200 push dword ptr [00429E74]
* Possible StringData Ref from Data Obj ->"Thank you for registering Hotkey "
----注册成功信息
->"Master."
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:0041450B 68849F4200 push 00429F84
:00414510 EB0C jmp 0041451E
* Referenced by a (U)nconditional or (C)onditional Jump at Address:
|:004144CB(C)
|
:00414512 56 push esi
:00414513 FF35749E4200 push dword ptr [00429E74]
* Possible StringData Ref from Data Obj ->"The key you entered is not correct."
----这里是出错信息,向上查找关键CALL和跳转
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:00414519 68609F4200 push 00429F60
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00412C05 /$ 55 PUSH EBP ----进入004144C1时停在这里
00412C06 |. 8BEC MOV EBP,ESP
00412C08 |. 51 PUSH ECX
00412C09 |. FF75 08 PUSH DWORD PTR SS:[EBP+8]
00412C0C |. 8365 FC 00 AND DWORD PTR SS:[EBP-4],0
00412C10 |. E8 BB230000 CALL Hotkey_M.00414FD0
00412C15 |. 33D2 XOR EDX,EDX
00412C17 |. 59 POP ECX
00412C18 |. 85C0 TEST EAX,EAX
00412C1A |. 7E 2E JLE SHORT Hotkey_M.00412C4A
00412C1C |. 53 PUSH EBX
00412C1D |. 56 PUSH ESI
00412C1E |. 57 PUSH EDI
00412C1F |. 8D70 0E LEA ESI,DWORD PTR DS:[EAX+E] EAX=用户名长度 SO
ESI=EAX+Eh
00412C22 |> 8B4D 08 /MOV ECX,DWORD PTR SS:[EBP+8] ----从这里开始是注
册算法
00412C25 |. 0FBE0C0A |MOVSX ECX,BYTE PTR DS:[EDX+ECX] ----依次计算用户名
的各个字节ASCII
00412C29 |. 8D79 0B |LEA EDI,DWORD PTR DS:[ECX+B]
----EDI=用户名长度+Bh
00412C2C |. 8D59 03 |LEA EBX,DWORD PTR DS:[ECX+3]
----EBX=用户名长度+3h
00412C2F |. 0FAFFB |IMUL EDI,EBX ----EDI*EBX的值放在
EDI
00412C32 |. 0FAFF9 |IMUL EDI,ECX ----EDI*ECX的值放在
EDI
00412C35 |. 0FAFFE |IMUL EDI,ESI ----EDI*ESI的值放在
EDI
00412C38 |. 8D48 05 |LEA ECX,DWORD PTR DS:[EAX+5]
00412C3B |. 0FAFF9 |IMUL EDI,ECX ----EDI*ECX的值放在
EDI
00412C3E |. 017D FC |ADD DWORD PTR SS:[EBP-4],EDI
00412C41 |. 42 |INC EDX ----EDX+1
00412C42 |. 46 |INC ESI ----ESI+1
00412C43 |. 3BD0 |CMP EDX,EAX ----算完了没有?没有
!那就继续从00412C25开始
00412C45 |.^7C DB \JL SHORT Hotkey_M.00412C22 ----循环计算
00412C47 |. 5F POP EDI
00412C48 |. 5E POP ESI
00412C49 |. 5B POP EBX
00412C4A |> 8B45 FC MOV EAX,DWORD PTR SS:[EBP-4] ----这里保存真注册码的十六
进制
00412C4D |. C9 LEAVE
00412C4E \. C3 RETN
4.总结
注册码通过用户名计算,将依次计算的结果相加再转换为十进制:
用户名=N
注册码=S
用户名长度=X
我们假设用户名为wolflh
S1=((N1+3h)*(N1+Bh)*N1*(X+5h))*(X+5h)
S2=((N1+3h)*(N1+Bh)*N1*(X+5h+1))*(X+5h)
S3=((N1+3h)*(N1+Bh)*N1*(X+5h+2))*(X+5h)
S4=((N1+3h)*(N1+Bh)*N1*(X+5h+3))*(X+5h)
S5=((N1+3h)*(N1+Bh)*N1*(X+5h+4))*(X+5h)
S6=((N1+3h)*(N1+Bh)*N1*(X+5h+5))*(X+5h)
S=S1+S2+S3+S4+S5+S6
软件注册成功后会在[HKEY_CURRENT_USER\Software\Mario Knok\Hotkey Master]下添加两个键值
"Registered Name"="wolflh"
"Registered Key"="2151786450"
删除这两个键值,又变成未注册版.
恕小子我刚加入"风飘雪",很少写过破文.对汇编知识和语言的谁知几乎为零,所以大部分算法都是自己乱猜的.分析如有错误,欢迎指出.
