idm version : 6.38 Build 23
2.算法逆向
IDM的序列号验证函数定位在：
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2021-6-1 16:08 上传
下面是在IDA下的代码分析:
.text:00510010 push ebp
.text:00510011 lea ebp, [esp-1FCh]
.text:00510018 sub esp, 1FCh
.text:0051001E push 0FFFFFFFFh
.text:00510020 push offset SEH_510010
.text:00510025 mov eax, large fs:0
.text:0051002B push eax
.text:0051002C sub esp, 160h
.text:00510032 mov eax, ___security_cookie
.text:00510037 xor eax, ebp
.text:00510039 mov [ebp+1FCh+var_4], eax
.text:0051003F push ebx
.text:00510040 push esi
.text:00510041 push edi
.text:00510042 push eax
.text:00510043 lea eax, [ebp+1FCh+var_208]
.text:00510046 mov large fs:0, eax
.text:0051004C mov [ebp+1FCh+var_20C], esp
.text:0051004F mov edi, ecx
.text:00510051 mov [ebp+1FCh+var_234], edi
.text:00510054 mov encode36, 32h ; '2' ; char basecode36[] = {0x32, 0x59, 0x4F, 0x50, 0x42, 0x33, 0x41, 0x51, 0x43, 0x56, 0x55, 0x58, 0x4D, 0x4E, 0x52, 0x53,0x39, 0x37, 0x57, 0x45, 0x30, 0x49, 0x5A, 0x44, 0x34, 0x4B, 0x4C, 0x46, 0x47, 0x48, 0x4A, 0x38,0x31, 0x36, 0x35, 0x54};
.text:0051005B mov encode36+1, 59h ; 'Y'
.text:00510062 mov encode36+2, 4Fh ; 'O'
.text:00510069 mov encode36+3, 50h ; 'P'
.text:00510070 mov encode36+4, 42h ; 'B'
.text:00510077 mov encode36+5, 33h ; '3'
.text:0051007E mov encode36+6, 41h ; 'A'
.text:00510085 mov encode36+7, 51h ; 'Q'
.text:0051008C mov encode36+8, 43h ; 'C'
.text:00510093 mov encode36+9, 56h ; 'V'
.text:0051009A mov encode36+0Ah, 55h ; 'U'
.text:005100A1 mov encode36+0Bh, 58h ; 'X'
.text:005100A8 mov encode36+0Ch, 4Dh ; 'M'
.text:005100AF mov encode36+0Dh, 4Eh ; 'N'
.text:005100B6 mov encode36+0Eh, 52h ; 'R'
.text:005100BD mov encode36+0Fh, 53h ; 'S'
.text:005100C4 mov encode36+10h, 39h ; '9'
.text:005100CB mov encode36+11h, 37h ; '7'
.text:005100D2 mov encode36+12h, 57h ; 'W'
.text:005100D9 mov encode36+13h, 45h ; 'E'
.text:005100E0 mov encode36+14h, 30h ; '0'
.text:005100E7 mov encode36+15h, 49h ; 'I'
.text:005100EE mov encode36+16h, 5Ah ; 'Z'
.text:005100F5 mov encode36+17h, 44h ; 'D'
.text:005100FC mov encode36+18h, 34h ; '4'
.text:00510103 mov encode36+19h, 4Bh ; 'K'
.text:0051010A mov encode36+1Ah, 4Ch ; 'L'
.text:00510111 mov encode36+1Bh, 46h ; 'F'
.text:00510118 mov encode36+1Ch, 47h ; 'G'
.text:0051011F mov encode36+1Dh, 48h ; 'H'
.text:00510126 mov encode36+1Eh, 4Ah ; 'J'
.text:0051012D mov encode36+1Fh, 38h ; '8'
.text:00510134 mov encode36+20h, 31h ; '1'
.text:0051013B mov encode36+21h, 36h ; '6'
.text:00510142 mov encode36+22h, 35h ; '5'
.text:00510149 mov encode36+23h, 54h ; 'T'
.text:00510150 mov [ebp+1FCh+var_200], 0
.text:00510157 push 32h ; '2' ; int
.text:00510159 lea eax, [ebp+1FCh+Data]
.text:0051015F push eax ; lpString
.text:00510160 push 4B0h ; nIDDlgItem
.text:00510165 call ?GetDlgItemTextA@CWnd@@QBEHHPADH@Z ; CWnd::GetDlgItemTextA(int,char *,int)
.text:0051016A test eax, eax
.text:0051016C jnz short loc_5101AC ; 获取注册名字并判断是否成功
.text:0051016E push eax ; uType
.text:0051016F push offset Caption ; "Internet Download Manager"
.text:00510174 mov ecx, dword_716978
.text:0051017A
.text:0051017A loc_51017A: ; CODE XREF: SerialCheck+1C1↓j
.text:0051017A ; SerialCheck+1E8↓j ...
.text:0051017A push ecx ; lpMultiByteStr
.text:0051017B mov edx, [edi+20h]
.text:0051017E push edx ; hWnd
.text:0051017F
.text:0051017F loc_51017F: ; CODE XREF: SerialCheck+271↓j
.text:0051017F ; SerialCheck+3F7↓j
.text:0051017F call MyMessageBox ; 弹出假冒序列号窗口函数
.text:00510184 add esp, 10h
.text:00510187
.text:00510187 loc_510187: ; CODE XREF: SerialCheck+5CF↓j
.text:00510187 ; SerialCheck+63B↓j ...
.text:00510187 mov ecx, [ebp+1FCh+var_208]
.text:0051018A mov large fs:0, ecx
.text:00510191 pop ecx
.text:00510192 pop edi
.text:00510193 pop esi
.text:00510194 pop ebx
.text:00510195 mov ecx, [ebp+1FCh+var_4]
.text:0051019B xor ecx, ebp ; StackCookie
.text:0051019D call @__security_check_cookie@4 ; __security_check_cookie(x)
.text:005101A2 add ebp, 1FCh
.text:005101A8 mov esp, ebp
.text:005101AA pop ebp
.text:005101AB retn
.text:005101AC ; ---------------------------------------------------------------------------
.text:005101AC
.text:005101AC loc_5101AC: ; CODE XREF: SerialCheck+15C↑j
.text:005101AC push 32h ; '2' ; int
.text:005101AE lea eax, [ebp+1FCh+var_CC]
.text:005101B4 push eax ; lpString
.text:005101B5 push 413h ; nIDDlgItem
.text:005101BA mov ecx, edi ; this
.text:005101BC call ?GetDlgItemTextA@CWnd@@QBEHHPADH@Z ; CWnd::GetDlgItemTextA(int,char *,int)
.text:005101C1 test eax, eax
.text:005101C3 jnz short loc_5101D3 ; 获取注册姓氏并判断是否成功
.text:005101C5 push eax
.text:005101C6 push offset Caption ; "Internet Download Manager"
.text:005101CB mov ecx, dword_71697C
.text:005101D1 jmp short loc_51017A
.text:005101D3 ; ---------------------------------------------------------------------------
.text:005101D3
.text:005101D3 loc_5101D3: ; CODE XREF: SerialCheck+1B3↑j
.text:005101D3 push 32h ; '2' ; int
.text:005101D5 lea eax, [ebp+1FCh+var_100]
.text:005101DB push eax ; lpString
.text:005101DC push 4A5h ; nIDDlgItem
.text:005101E1 mov ecx, edi ; this
.text:005101E3 call ?GetDlgItemTextA@CWnd@@QBEHHPADH@Z ; CWnd::GetDlgItemTextA(int,char *,int)
.text:005101E8 test eax, eax
.text:005101EA jnz short loc_5101FA ; 获取注册邮箱并判断是否成功
.text:005101EC push eax
.text:005101ED push offset Caption ; "Internet Download Manager"
.text:005101F2 mov ecx, dword_716980
.text:005101F8 jmp short loc_51017A
.text:005101FA ; ---------------------------------------------------------------------------
.text:005101FA
.text:005101FA loc_5101FA: ; CODE XREF: SerialCheck+1DA↑j
.text:005101FA push 32h ; '2' ; int
.text:005101FC lea eax, [ebp+1FCh+RegisterSerialNumber]
.text:00510202 push eax ; lpString
.text:00510203 push 4AAh ; nIDDlgItem
.text:00510208 mov ecx, edi ; this
.text:0051020A call ?GetDlgItemTextA@CWnd@@QBEHHPADH@Z ; CWnd::GetDlgItemTextA(int,char *,int)
.text:0051020F test eax, eax
.text:00510211 jnz short loc_510224 ; 获取序列号并判断是否成功
.text:00510213 push eax
.text:00510214 push offset Caption ; "Internet Download Manager"
.text:00510219 mov ecx, dword_716984
.text:0051021F jmp loc_51017A
.text:00510224 ; ---------------------------------------------------------------------------
.text:00510224
.text:00510224 loc_510224: ; CODE XREF: SerialCheck+201↑j
.text:00510224 mov bl, 20h ; ' ' ; bl = 0x20(' ')
.text:00510226
.text:00510226 loc_510226: ; CODE XREF: SerialCheck+24A↓j
.text:00510226 cmp [ebp+1FCh+RegisterSerialNumber], bl ; 比对序列号的第一位是否是空格
.text:0051022C jnz short loc_51025C
.text:0051022E push 32h ; '2' ; int
.text:00510230 lea eax, [ebp+1FCh+var_57]
.text:00510236 push eax ; Source
.text:00510237 lea ecx, [ebp+1FCh+var_1FC]
.text:0051023A push ecx ; Destination
.text:0051023B call sub_405380
.text:00510240 add esp, 0Ch
.text:00510243 lea ecx, [ebp+1FCh+var_1FC]
.text:00510246 lea edx, [ebp+1FCh+RegisterSerialNumber]
.text:0051024C lea esp, [esp+0]
.text:00510250
.text:00510250 loc_510250: ; CODE XREF: SerialCheck+248↓j
.text:00510250 mov al, [ecx]
.text:00510252 mov [edx], al
.text:00510254 inc ecx
.text:00510255 inc edx
.text:00510256 test al, al
.text:00510258 jnz short loc_510250
.text:0051025A jmp short loc_510226
.text:0051025C ; ---------------------------------------------------------------------------
.text:0051025C
.text:0051025C loc_51025C: ; CODE XREF: SerialCheck+21C↑j
.text:0051025C lea eax, [ebp+1FCh+RegisterSerialNumber] ; EAX = 序列号的第一位地址
.text:00510262 lea edx, [eax+1] ; EDX = 序列号的第二位的地址
.text:00510265
.text:00510265 loc_510265: ; CODE XREF: SerialCheck+25A↓j
.text:00510265 mov cl, [eax]
.text:00510267 inc eax
.text:00510268 test cl, cl
.text:0051026A jnz short loc_510265
.text:0051026C sub eax, edx ; 计算序列号的个数
.text:0051026E jnz short loc_510290
.text:00510270 push eax
.text:00510271 push offset Caption ; "Internet Download Manager"
.text:00510276 mov edx, dword_716988
.text:0051027C push edx
.text:0051027D mov eax, [edi+20h]
.text:00510280 push eax
.text:00510281 jmp loc_51017F
.text:00510281 ; } // starts at 510010
.text:00510281 SerialCheck endp
.text:00510281
.text:00510286 ; ---------------------------------------------------------------------------
.text:00510286 jmp short loc_510290
.text:00510286 ; ---------------------------------------------------------------------------
.text:00510288 align 10h
.text:00510290 ; START OF FUNCTION CHUNK FOR SerialCheck
.text:00510290
.text:00510290 loc_510290: ; CODE XREF: SerialCheck+25E↑j
.text:00510290 ; .text:00510286↑j ...
.text:00510290 ; __unwind { // SEH_510010 ; EAX = 序列号的第一位地址
.text:00510290 lea eax, [ebp+1FCh+RegisterSerialNumber]
.text:00510296 lea edx, [eax+1] ; EDX = 序列号的第二位地址
.text:00510299 lea esp, [esp+0]
.text:005102A0
.text:005102A0 loc_5102A0: ; CODE XREF: SerialCheck+295↓j
.text:005102A0 mov cl, [eax]
.text:005102A2 inc eax
.text:005102A3 test cl, cl
.text:005102A5 jnz short loc_5102A0
.text:005102A7 sub eax, edx ; 计算序列号的长度
.text:005102A9 cmp [ebp+eax+1FCh+var_59], bl ; 比对序列号的最后一位是否等于0x20(' ')
.text:005102B0 jnz short loc_5102D2
.text:005102B2 lea eax, [ebp+1FCh+RegisterSerialNumber]
.text:005102B8 lea edx, [eax+1]
.text:005102BB jmp short loc_5102C0
.text:005102BB ; } // starts at 510290
.text:005102BB ; END OF FUNCTION CHUNK FOR SerialCheck
.text:005102BB ; ---------------------------------------------------------------------------
.text:005102BD align 10h
.text:005102C0 ; START OF FUNCTION CHUNK FOR SerialCheck
.text:005102C0
.text:005102C0 loc_5102C0: ; CODE XREF: SerialCheck+2AB↑j
.text:005102C0 ; SerialCheck+2B5↓j
.text:005102C0 ; __unwind { // SEH_510010
.text:005102C0 mov cl, [eax]
.text:005102C2 inc eax
.text:005102C3 test cl, cl
.text:005102C5 jnz short loc_5102C0
.text:005102C7 sub eax, edx
.text:005102C9 mov [ebp+eax+1FCh+var_59], cl
.text:005102D0 jmp short loc_510290
.text:005102D2 ; ---------------------------------------------------------------------------
.text:005102D2
.text:005102D2 loc_5102D2: ; CODE XREF: SerialCheck+2A0↑j
.text:005102D2 lea ecx, [ebp+1FCh+RegisterSerialNumber]
.text:005102D8 push ecx ; String
.text:005102D9 call __strupr ; 把序列号全部为大写
.text:005102DE add esp, 4
.text:005102E1 lea eax, [ebp+1FCh+RegisterSerialNumber] ; EAX = 序列号的第一位地址
.text:005102E7 lea edx, [eax+1] ; EDX = 序列号的第二位地址
.text:005102EA lea ebx, [ebx+0]
.text:005102F0
.text:005102F0 loc_5102F0: ; CODE XREF: SerialCheck+2E5↓j
.text:005102F0 mov cl, [eax]
.text:005102F2 inc eax
.text:005102F3 test cl, cl
.text:005102F5 jnz short loc_5102F0
.text:005102F7 sub eax, edx ; 计算序列号的长度
.text:005102F9 cmp eax, 17h
.text:005102FC jnz loc_5103F6 ; 判断序列号的长短是否等于23（0x17）
.text:00510302 xor bl, bl ; bl = 0;
.text:00510304 mov al, 2Dh ; '-' ; al = '-'(0x2d);
.text:00510306 cmp [ebp+1FCh+var_53], al ; 判断序列号的第六位是否等于'-'(0x2d)
.text:0051030C jnz short loc_51031E
.text:0051030E cmp [ebp+1FCh+var_4D], al ; 判断序列号的第12位是否等于'-'(0x2d)
.text:00510314 jnz short loc_51031E
.text:00510316 cmp [ebp+1FCh+var_47], al ; 判断序列号的第18位是否等于'-'(0x2d)
.text:0051031C jz short loc_510320
.text:0051031E
.text:0051031E loc_51031E: ; CODE XREF: SerialCheck+2FC↑j
.text:0051031E ; SerialCheck+304↑j
.text:0051031E mov bl, 1
.text:00510320
.text:00510320 loc_510320: ; CODE XREF: SerialCheck+30C↑j
.text:00510320 push 5 ; Count
.text:00510322 lea edx, [ebp+1FCh+RegisterSerialNumber]
.text:00510328 push edx ; Source
.text:00510329 lea eax, [ebp+1FCh+RegisterSerialNumber_0_5]
.text:0051032F push eax ; Destination
.text:00510330 call _strncpy ; 取出序列号的0-5位
.text:00510335 push 5 ; Count
.text:00510337 lea ecx, [ebp+1FCh+Source]
.text:0051033D push ecx ; Source
.text:0051033E lea edx, [ebp+1FCh+RegisterSerialNumber_6_11]
.text:00510344 push edx ; Destination
.text:00510345 call _strncpy ; 取出序列号的6-11位
.text:0051034A push 5 ; Count
.text:0051034C lea eax, [ebp+1FCh+var_4C]
.text:00510352 push eax ; Source
.text:00510353 lea ecx, [ebp+1FCh+RegisterSerialNumber_13_17]
.text:00510359 push ecx ; Destination
.text:0051035A call _strncpy ; 取出序列号的13-17位
.text:0051035F push 5 ; Count
.text:00510361 lea edx, [ebp+1FCh+var_46]
.text:00510367 push edx ; Source
.text:00510368 lea eax, [ebp+1FCh+RegisterSerialNumber_18_23]
.text:0051036E push eax ; Destination
.text:0051036F call _strncpy ; 取出序列号的18-23位
.text:00510374 mov [ebp+1FCh+var_7], 0
.text:0051037B mov [ebp+1FCh+var_F], 0
.text:00510382 mov [ebp+1FCh+var_1F], 0
.text:00510389 mov [ebp+1FCh+var_17], 0 ; 在每个取出的5位序列号后面添加0x00
.text:00510390 lea ecx, [ebp+1FCh+encode_1]
.text:00510393 push ecx
.text:00510394 lea edx, [ebp+1FCh+RegisterSerialNumber_0_5]
.text:0051039A push edx
.text:0051039B call SerialEncrypt ; 序列号加密函数
.text:005103A0 add esp, 38h
.text:005103A3 test eax, eax
.text:005103A5 jnz short loc_5103A9 ; 返回值等于1跳转,等于0则 bl = 0x01
.text:005103A7 mov bl, 1
.text:005103A9
.text:005103A9 loc_5103A9: ; CODE XREF: SerialCheck+395↑j
.text:005103A9 lea eax, [ebp+1FCh+encode_2+4]
.text:005103AC push eax
.text:005103AD lea ecx, [ebp+1FCh+RegisterSerialNumber_6_11]
.text:005103B3 push ecx
.text:005103B4 call SerialEncrypt ; 序列号加密函数
.text:005103B9 add esp, 8
.text:005103BC test eax, eax
.text:005103BE jnz short loc_5103C2 ; 返回值等于1跳转,等于0则 bl = 0x01
.text:005103C0 mov bl, 1
.text:005103C2
.text:005103C2 loc_5103C2: ; CODE XREF: SerialCheck+3AE↑j
.text:005103C2 lea edx, [ebp+1FCh+encode_3]
.text:005103C5 push edx
.text:005103C6 lea eax, [ebp+1FCh+RegisterSerialNumber_13_17]
.text:005103CC push eax
.text:005103CD call SerialEncrypt ; 序列号加密函数
.text:005103D2 add esp, 8
.text:005103D5 test eax, eax
.text:005103D7 jnz short loc_5103DB ; 返回值等于1跳转,等于0则 bl = 0x01
.text:005103D9 mov bl, 1
.text:005103DB
.text:005103DB loc_5103DB: ; CODE XREF: SerialCheck+3C7↑j
.text:005103DB lea ecx, [ebp+1FCh+encode_4]
.text:005103DE push ecx
.text:005103DF lea edx, [ebp+1FCh+RegisterSerialNumber_18_23]
.text:005103E5 push edx
.text:005103E6 call SerialEncrypt ; 序列号加密函数
.text:005103EB add esp, 8
.text:005103EE test eax, eax
.text:005103F0 jz short loc_5103F6
.text:005103F2 test bl, bl
.text:005103F4 jz short loc_51040C ; 判断上面的每个函数都返回1 则跳转
.text:005103F6
.text:005103F6 loc_5103F6: ; CODE XREF: SerialCheck+2EC↑j
.text:005103F6 ; SerialCheck+3E0↑j ...
.text:005103F6 push 0
.text:005103F8 push offset Caption ; "Internet Download Manager"
.text:005103FD mov eax, dword_716988
.text:00510402 push eax
.text:00510403 mov ecx, [edi+20h]
.text:00510406 push ecx
.text:00510407 jmp loc_51017F
.text:0051040C ; ---------------------------------------------------------------------------
.text:0051040C
.text:0051040C loc_51040C: ; CODE XREF: SerialCheck+3E4↑j
.text:0051040C mov ecx, [ebp+1FCh+encode_1]
.text:0051040F mov eax, 2FA0BE83h
.text:00510414 imul ecx
.text:00510416 sar edx, 3
.text:00510419 mov eax, edx
.text:0051041B shr eax, 1Fh
.text:0051041E add eax, edx
.text:00510420 imul eax, 2Bh ; '+'
.text:00510423 mov edx, ecx
.text:00510425 sub edx, eax ; edx = encode1 % 43;
.text:00510427 jnz short loc_51042D ; 判断序列号第一部分的加密的结果除于43取余是否等于0
.text:00510429 test ecx, ecx
.text:0051042B jnz short loc_51042F
.text:0051042D
.text:0051042D loc_51042D: ; CODE XREF: SerialCheck+417↑j
.text:0051042D mov bl, 1
.text:0051042F
.text:0051042F loc_51042F: ; CODE XREF: SerialCheck+41B↑j
.text:0051042F mov ecx, dword ptr [ebp+1FCh+encode_2+4]
.text:00510432 mov eax, 0B21642C9h
.text:00510437 imul ecx
.text:00510439 add edx, ecx
.text:0051043B sar edx, 4
.text:0051043E mov eax, edx
.text:00510440 shr eax, 1Fh
.text:00510443 add eax, edx
.text:00510445 imul eax, 17h
.text:00510448 mov edx, ecx
.text:0051044A sub edx, eax ; edx = encode2 % 23;
.text:0051044C jnz short loc_510452 ; 判断序列号第二部分的加密的结果除于23取余是否等于0
.text:0051044E test ecx, ecx
.text:00510450 jnz short loc_510454
.text:00510452
.text:00510452 loc_510452: ; CODE XREF: SerialCheck+43C↑j
.text:00510452 mov bl, 1
.text:00510454
.text:00510454 loc_510454: ; CODE XREF: SerialCheck+440↑j
.text:00510454 mov ecx, [ebp+1FCh+encode_3]
.text:00510457 mov eax, 78787879h
.text:0051045C imul ecx
.text:0051045E sar edx, 3
.text:00510461 mov eax, edx
.text:00510463 shr eax, 1Fh
.text:00510466 add eax, edx
.text:00510468 mov edx, eax
.text:0051046A shl edx, 4
.text:0051046D add edx, eax
.text:0051046F mov eax, ecx
.text:00510471 sub eax, edx ; eax = encode_3 % 17;
.text:00510473 jnz short loc_510479 ; 判断序列号第三部分的加密的结果除于17取余是否等于0
.text:00510475 test ecx, ecx
.text:00510477 jnz short loc_51047B
.text:00510479
.text:00510479 loc_510479: ; CODE XREF: SerialCheck+463↑j
.text:00510479 mov bl, 1
.text:0051047B
.text:0051047B loc_51047B: ; CODE XREF: SerialCheck+467↑j
.text:0051047B mov ecx, [ebp+1FCh+encode_4]
.text:0051047E mov eax, 4D4873EDh
.text:00510483 imul ecx
.text:00510485 sar edx, 4
.text:00510488 mov eax, edx
.text:0051048A shr eax, 1Fh
.text:0051048D add eax, edx
.text:0051048F imul eax, 35h ; '5'
.text:00510492 mov edx, ecx
.text:00510494 sub edx, eax ; edx = encode_4 % 53;
.text:00510496 jnz loc_5103F6 ; 判断序列号第四部分的加密的结果除于53取余是否等于0
.text:0051049C test ecx, ecx
.text:0051049E jz loc_5103F6
.text:005104A4 test bl, bl
.text:005104A6 jnz loc_5103F6 ; 判断bl是否等于1 也就是判断上面的验证是否都是正确的
.text:005104AC push 8 ; Count
.text:005104AE lea edx, [ebp+1FCh+RegisterSerialNumber]
.text:005104B4 push edx ; Source
.text:005104B5 lea eax, [ebp+1FCh+ArgList]
.text:005104BB push eax ; Destination
.text:005104BC call _strncpy ; 取出序列号的前八位
根据上面的代码逆向出序列号验证流程：
1.获取注册的 名字 姓氏 邮箱 序列号
2.如果序列号的开头或结尾是空格的话就去掉空格
3.把序列号转换成大写
4.判断序列号的长度是否等于23(0x17),并序列号的第6位,第12位，第18位是否等于‘-’(0x2d)
5.分别取出4部分的5位序列号xxxxx进行加密得到4个无符号数
6.判断序列号是否正确，条件如下：
第一部分的5位序列号加密后的无符号数除于43取余是否等于0
第二部分的5位的序列号加密后的无符号数处于23取余是否等于0
第三部分的5位的序列号加密后的无符号数处于17取余是否等于0
第四部分的5位的序列号加密后的无符号数处于53取余是否等于0
之后就是把注册信息写入到注册表和网络验证，这里不讨论
在text:0051039B,005103B4,text:005103CD,text:005103E6 这4处调用的加密函数 IDA反汇编代码如下：
.text:0050F050 SerialEncrypt proc near ; CODE XREF: SerialCheck+38B↓p
.text:0050F050 ; SerialCheck+3A4↓p ...
.text:0050F050
.text:0050F050 arg_0 = dword ptr 4
.text:0050F050 arg_4 = dword ptr 8
.text:0050F050
.text:0050F050 push esi
.text:0050F051 mov esi, [esp+4+arg_4] ; esi = arg_4;
.text:0050F055 push edi
.text:0050F056 mov edi, [esp+8+arg_0] ; edi = arg_0;
.text:0050F05A mov dword ptr [esi], 0 ; *esi = (4 byte)0x00;
.text:0050F060 xor ecx, ecx ; ecx = 0
.text:0050F062
.text:0050F062 loc_50F062: ; CODE XREF: SerialEncrypt+3C↓j
.text:0050F062 mov dl, [ecx+edi] ; dl = arg_0[ecx];
.text:0050F065 xor eax, eax ; eax = 0;
.text:0050F067
.text:0050F067 loc_50F067: ; CODE XREF: SerialEncrypt+23↓j
.text:0050F067 cmp encode36[eax], dl
.text:0050F06D jz short loc_50F07A ; 判断encode36[eax]是否等于arg_0[ecx]
.text:0050F06F inc eax ; eax++;
.text:0050F070 cmp eax, 24h ; '$'
.text:0050F073 jl short loc_50F067 ; 判断eax是否小于36(0x24)
.text:0050F075
.text:0050F075 loc_50F075: ; CODE XREF: SerialEncrypt+2D↓j
.text:0050F075 pop edi
.text:0050F076 xor eax, eax ; return 0;
.text:0050F078 pop esi
.text:0050F079 retn
.text:0050F07A ; ---------------------------------------------------------------------------
.text:0050F07A
.text:0050F07A loc_50F07A: ; CODE XREF: SerialEncrypt+1D↑j
.text:0050F07A cmp eax, 0FFFFFFFFh
.text:0050F07D jz short loc_50F075 ; 判断eax是否等于-1(0xFFFFFFFF)
.text:0050F07F mov edx, [esi]
.text:0050F081 imul edx, 25h ; '%'
.text:0050F084 add edx, eax
.text:0050F086 inc ecx
.text:0050F087 cmp ecx, 5
.text:0050F08A mov [esi], edx ; *arg_0 = *arg_0 * 37(0x25) + eax;
.text:0050F08C jl short loc_50F062 ; 判断eax是否小于5
.text:0050F08E pop edi
.text:0050F08F mov eax, 1 ; return 1;
.text:0050F094 pop esi
.text:0050F095 retn
.text:0050F095 SerialEncrypt endp
对应的C++代码
const char kEnCode36[] = { 0x32, 0x59, 0x4F, 0x50, 0x42, 0x33, 0x41, 0x51, 0x43, 0x56, 0x55, 0x58, 0x4D, 0x4E, 0x52, 0x53,0x39, 0x37, 0x57, 0x45, 0x30, 0x49, 0x5A, 0x44, 0x34, 0x4B, 0x4C, 0x46, 0x47, 0x48, 0x4A, 0x38,0x31, 0x36, 0x35, 0x54 };
int __cdecl sub_50e990(const char* serial_number, int* arg_4)
{
*arg_4 = 0;
for (int serial_number_count = 0; serial_number_count = 36) return 0;
}
if (encode36_count == 0XFFFFFFFF) return 0;
*arg_4 = *arg_4 * 37 + encode36_count;
}
return 1;
}
序列号分为4部分,每部分的5位序列号分别用sub_50e990加密.Encode36的内容为 2YOPB3AQCVUXMNRS97WE0IZD4KLFGHJ8165T实际上就是所有的字母和数字,sub_50e990函数的加密过程就是先把arg_4初始化为0，之后计算arg_4乘以37+当前序列号在Encode36的Count得到的结果赋值给arg_4在进行下一次计算.循环5次得到一个无符号数之后在进行相对应的整除判断。现在知道了他的序列号验证过程就可以反向推导出序列号
const char kEnCode36[] = { 0x32, 0x59, 0x4F, 0x50, 0x42, 0x33, 0x41, 0x51, 0x43, 0x56, 0x55, 0x58, 0x4D, 0x4E, 0x52, 0x53,0x39, 0x37, 0x57, 0x45, 0x30, 0x49, 0x5A, 0x44, 0x34, 0x4B, 0x4C, 0x46, 0x47, 0x48, 0x4A, 0x38,0x31, 0x36, 0x35, 0x54 };
int SnGenerate(unsigned int base,char* serial_number,int serial_size)
{
if (serial_size
完整的计算序列号代码：
#include
#include
using namespace std;
#pragma warning(disable:4996)
// "2YOPB3AQCVUXMNRS97WE0IZD4KLFGHJ8165T"
const char kEnCode36[] = { 0x32, 0x59, 0x4F, 0x50, 0x42, 0x33, 0x41, 0x51, 0x43, 0x56, 0x55, 0x58, 0x4D, 0x4E, 0x52, 0x53,0x39, 0x37, 0x57, 0x45, 0x30, 0x49, 0x5A, 0x44, 0x34, 0x4B, 0x4C, 0x46, 0x47, 0x48, 0x4A, 0x38,0x31, 0x36, 0x35, 0x54 };
int SnGenerate(unsigned int base,char* serial_number,int serial_size)
{
if (serial_size
