How to reverse engineer +Sync's protection
(You'll find it in the SECOND PHASE of "our protections" section)

by +Sync, 13 August 1997

HCU

Courtesy of Fravia's page of reverse engineering

Well, let's hope that programmers will NOT use protection schemes based on +Sync's findings, the math involved is awesom! We would crack such a scheme anyway, of course, but there may come a point where cracking a protection is too fatiguing to be worth the try... altough I would not count on it: the more complex it is the more worth is it to crack... let's not forget that we DO NOT CARE for the programs we crack... we care for the complexity of the protection scheme itself!
This said, you have here a "terrific" protection scheme from +Sync (one of the few +HCUkers since the 1996 "strainer"), it is jolly well WORTH studing if you are seriously into software protection (or deprotection, which amounts to the same interests :-) 
How to Reverse Engineer Register v1.0
By +Sync
Find Target: At Fravia's Page of Reverse Engineering (of course) Tools Used: WinIce 3.0 (Godot), WDASM 8.9, Hex Workshop Time Required: Depends on how in depth you study it
Took over 8 hours to write program, about 2 to write this essay.
Well here is the solution to the REGISTER.EXE program I wrote. I'm guessing that not many people attempted to crack it, because as of this writing, almost 3 weeks after releasing it, only one valid code has been turned in to me. I would like to thank +Daq for his great work and enthusiasm for this project, not to mention a working name/number sequence. I would also like to thank jOb for his response - while he did not go through all of the details he did have an almost perfect explaination of the code, and I'm certain he was capable of reversing it if he had taken the time. However, I commend him for his choice NOT to work on it. Understanding the code is enough, why work tediously on an excercise when there are real Micro$oft programs to destroy? There were several patches turned in, however patching (especially in this case where I gave you a valid name/number pair) was much easier than reversing the code generating algorithm. I decided that to be complete I would include both the C and ASM code to this program. I will warn you now that there is ALOT of code to wade through in this text. It is not necessary to go through line by line, just look at the areas that you don't understand. I decided that to include the complete ASM code would be better than just short snippets because then you can see how the C code is converted by the compiler. You will notice several inneficient ways that the code was generated. I would like to thank +Daq for his interest in my program, his was the only response I received which attempted to understand how the code is generated, and he did fine work. Please examine this code as closely as you like: it is deliberately choppy, as this hinders it's reversal. I commented as well as I think necessary, but if you REALLY can't figure something out just let me know. All math in the C code is done in decimal form (kind of like reading greek after using hex exclusively). I hope this project will be helpful to someone. ----------------------------------------------------------------- void Register::OnRegButton() { int RegFlag[4]; // 69 = good int i; int NameSum; CString Temp1= "UareaisrerGd"; //poor attempt at encrypting text CString Temp2= "URrbgis8ered"; CString Temp3= "Sync5ister+d"; CString Temp4= "VnrQ7isoered"; CString UnReg; CString Reg = "0123456789"; div_t DivResult; RegFlag[1]=69; RegFlag[2]=96; RegFlag[3]=99; UpdateData(TRUE); //Update m_name with whats in box SetupCheck(); UnReg = Temp1; // Set up 'UnRegistered' UnReg.SetAt(1,Temp4.GetAt(1)); UnReg.SetAt(4,Temp2.GetAt(4)); UnReg.SetAt(7,Temp3.GetAt(7)); UnReg.SetAt(10,Temp4.GetAt(10)); Reg.SetAt(0, Temp2.GetAt(1)); // Set up 'Registered' for (i=1 ; i<=9 ; i++) { Reg.SetAt(i, UnReg.GetAt(i+2)); } if (lstrlen(m_name)>= 3) // Name must be 3 chars long { i=Clean( toascii( m_name.GetAt(1) )); //2nd char cleaned on line 1 if (!check[(i-65)*10+2]) { RegFlag[1] =14; } else { testchk[(i-65)*10+2] = TRUE; } i=Clean( toascii( m_name.GetAt(0))+toascii( m_name.GetAt(1))+toascii( m_name.GetAt(2)) ); if (!check[(i-65)*10+3]) //(1st+2nd+3rd) cleaned on line 2 { RegFlag[2] =35; } else { testchk[(i-65)*10+3] = TRUE; } if (!check[164]) // "Q" on line 3 hard coded { RegFlag[3] = 48; } else { testchk[164] = TRUE; } i=Clean( toascii( m_name.GetAt(0) )); // 1st cleaned on line 4 if (!check[(i-65)*10+5]) { RegFlag[1] = 19; } else { testchk[(i-65)*10+5] = TRUE; } i=Clean( toascii( m_name.GetAt(1) )); // 2nd cleaned on line 4 if (!check[(i-65)*10+5]) { RegFlag[2] = 18; } else { testchk[(i-65)*10+5] = TRUE; } i=Clean( toascii( m_name.GetAt(2) )); // 3rd cleaned on line 4 if (!check[(i-65)*10+5]) { RegFlag[3] = 17; } else { testchk[(i-65)*10+5] = TRUE; } NameSum =0; // remainder of sum of all chars /69 cleaned on line 5 for (i=1; i <= m_name.GetLength(); i++ ) { NameSum +="m_name.GetAt(i-1);" } DivResult="div(NameSum," 69); i="Clean(DivResult.rem);" if (!check[(i-65)*10+6]) { RegFlag[1]="68;" } else { testchk[(i-65)*10+6]="TRUE;" } i="Clean(" toascii(m_name.GetAt(2))*6 ); // (6 * 3rd) cleaned on line 6 if (!check[(i-65)*10+7]) { RegFlag[2]="27;" } else { testchk[(i-65)*10+7]="TRUE;" } i="Clean(" toascii(m_name.GetAt(0))*toascii(m_name.GetAt(2)) ); if (!check[(i-65)*10+8]) // (1st * 3rd) cleaned on line 7 { RegFlag[3]="61;" } else { testchk[(i-65)*10+8]="TRUE;" } i="Clean(toascii(m_name.GetAt(0))-4);" //1st 4 cleaned on line 8 if (!check[(i-65)*10+9]) { RegFlag[1]="56;" } else { testchk[(i-65)*10+9]="TRUE;" } if (!check[190]) // "S" on line 9 hard coded { RegFlag[2]="47;" } else { testchk[190]="TRUE;" } if (!check[71]) // "H" on line 0 hard coded { RegFlag[3]="48;" } else { testchk[71]="TRUE;" } if (!check[21]) // "C" on line 0 hard coded { RegFlag[1]="59;" } else { testchk[21]="TRUE;" } if (!check[201]) // "U" on line 0 hard coded { RegFlag[2]="64;" } else { testchk[201]="TRUE;" } for (i="1" ; i <="210" ; i++) // make sure only correct checks are checke { // i.e. no extras. The two arrays should be same if (testchk[i] !="check[i])" { RegFlag[2]="i+100;" } } if (RegFlag[1] !="69)" //this section makes sure all 3 flags are unchanged { RegFlag[2]="56;" } if (RegFlag[2] !="96)" { RegFlag[3]="43;" } if (RegFlag[3]="=" 99) //if unchanged, your'e good guy { m_name="Reg;" UpdateData(FALSE); } else // otherwise you're a bad guy { m_name="UnReg;" UpdateData(FALSE); } } } int Register::Clean(int X) // Return int representing letters A-U // Simply subtracts or adds 10 until it is within 65-85 range { while (X> 85) { X=X-10; } while (X <65) { X="X+10;" } return X; } And now, as promised the ASM code "corresponding.class" tppabs="http://fravia.org/corresponding.class" to the C code above. :0040295E 90 nop :0040295F 90 nop :00402960 6AFF push FFFFFFFF :00402962 6840434000 push 00404340 :00402967 64A100000000 mov eax, fs:[00000000] :0040296D 50 push eax :0040296E 64892500000000 mov dword ptr fs:[00000000], esp :00402975 83EC30 sub esp, 00000030 :00402978 55 push ebp :00402979 56 push esi :0040297A 8BF1 mov esi, ecx :0040297C 57 push edi * Possible StringData Ref from Data Obj>"UareaisrerGd" =========================================================================== ;This and the three garbled below are combined to make "Registered" and "Unregistered" text fields. =========================================================================== | :0040297D 68A0604000 push 004060A0 :00402982 8D4C2424 lea ecx, dword ptr [esp + 24] * Reference To: MFC42.MFC42:NoName0127, Ord:0219h | :00402986 E86F140000 Call 00403DFA * Possible StringData Ref from Data Obj ->"URrbgis8ered" | :0040298B 6890604000 push 00406090 :00402990 8D4C241C lea ecx, dword ptr [esp + 1C] :00402994 C744244800000000 mov [esp + 48], 00000000 * Reference To: MFC42.MFC42:NoName0127, Ord:0219h | :0040299C E859140000 Call 00403DFA * Possible StringData Ref from Data Obj ->"Sync5ister+d" | :004029A1 6880604000 push 00406080 :004029A6 8D4C2420 lea ecx, dword ptr [esp + 20] :004029AA C644244801 mov [esp + 48], 01 * Reference To: MFC42.MFC42:NoName0127, Ord:0219h | :004029AF E846140000 Call 00403DFA * Possible StringData Ref from Data Obj ->"VnrQ7isoered" | :004029B4 6870604000 push 00406070 :004029B9 8D4C2418 lea ecx, dword ptr [esp + 18] :004029BD C644244802 mov [esp + 48], 02 * Reference To: MFC42.MFC42:NoName0127, Ord:0219h | :004029C2 E833140000 Call 00403DFA :004029C7 8D4C240C lea ecx, dword ptr [esp + 0C] :004029CB C644244403 mov [esp + 44], 03 * Reference To: MFC42.MFC42:NoName0120, Ord:021Ch | :004029D0 E8FB130000 Call 00403DD0 * Possible StringData Ref from Data Obj ->"0123456789" =========================================================================== ;This is where the "Registered" is stored, notice it is 10 characters long, just like "Registered". =========================================================================== | :004029D5 6864604000 push 00406064 :004029DA 8D4C2414 lea ecx, dword ptr [esp + 14] :004029DE C644244804 mov [esp + 48], 04 * Reference To: MFC42.MFC42:NoName0127, Ord:0219h | :004029E3 E812140000 Call 00403DFA :004029E8 6A01 push 00000001 :004029EA 8BCE mov ecx, esi :004029EC C644244805 mov [esp + 48], 05 :004029F1 C744243445000000 mov [esp + 34], 00000045 ;RegFlag[1] :004029F9 C744243860000000 mov [esp + 38], 00000060 ;RegFlag[2] :00402A01 C744243C63000000 mov [esp + 3C], 00000063 ;RegFlag[3] * Reference To: MFC42.MFC42:NoName0126, Ord:18BEh | :00402A09 E8E6130000 Call 00403DF4 :00402A0E 8BCE mov ecx, esi :00402A10 E83B040000 call 00402E50 :00402A15 8D442420 lea eax, dword ptr [esp + 20] :00402A19 8D4C240C lea ecx, dword ptr [esp + 0C] :00402A1D 50 push eax * Reference To: MFC42.MFC42:NoName0125, Ord:035Ah | :00402A1E E8CB130000 Call 00403DEE :00402A23 8B4C2414 mov ecx, dword ptr [esp + 14] :00402A27 8A5101 mov dl, byte ptr [ecx+01] :00402A2A 8D4C240C lea ecx, dword ptr [esp + 0C] :00402A2E 52 push edx :00402A2F 6A01 push 00000001 * Reference To: MFC42.MFC42:NoName0124, Ord:16E0h | :00402A31 E8B2130000 Call 00403DE8 =========================================================================== Trace into the call above (at 402A31) until it makes another call. AX will hold a memory location. Look at DS:AX and you will see Temp1. 2 Lines above you will see "0123456789". Keep your data window on this area as you trace through the next few calls. The strings will be constructed right before your eyes. For a more in depth look at what these calls are doing, see the C code. =========================================================================== :00402A36 8B442418 mov eax, dword ptr [esp + 18] :00402A3A 8A4804 mov cl, byte ptr [eax+04] :00402A3D 51 push ecx :00402A3E 6A04 push 00000004 :00402A40 8D4C2414 lea ecx, dword ptr [esp + 14] * Reference To: MFC42.MFC42:NoName0124, Ord:16E0h | :00402A44 E89F130000 Call 00403DE8 :00402A49 8B54241C mov edx, dword ptr [esp + 1C] :00402A4D 8D4C240C lea ecx, dword ptr [esp + 0C] :00402A51 8A4207 mov al, byte ptr [edx+07] :00402A54 50 push eax :00402A55 6A07 push 00000007 * Reference To: MFC42.MFC42:NoName0124, Ord:16E0h | :00402A57 E88C130000 Call 00403DE8 :00402A5C 8B4C2414 mov ecx, dword ptr [esp + 14] :00402A60 8A510A mov dl, byte ptr [ecx+0A] :00402A63 8D4C240C lea ecx, dword ptr [esp + 0C] :00402A67 52 push edx :00402A68 6A0A push 0000000A * Reference To: MFC42.MFC42:NoName0124, Ord:16E0h | :00402A6A E879130000 Call 00403DE8 :00402A6F 8B442418 mov eax, dword ptr [esp + 18] :00402A73 8A4801 mov cl, byte ptr [eax+01] :00402A76 51 push ecx :00402A77 6A00 push 00000000 :00402A79 8D4C2418 lea ecx, dword ptr [esp + 18] * Reference To: MFC42.MFC42:NoName0124, Ord:16E0h | :00402A7D E866130000 Call 00403DE8 :00402A82 BF01000000 mov edi, 00000001 * Referenced by a Jump at Address :00402A9E(C) | :00402A87 8B54240C mov edx, dword ptr [esp + 0C] :00402A8B 8D4C2410 lea ecx, dword ptr [esp + 10] :00402A8F 8A443A02 mov al, byte ptr [edx + edi + 02] :00402A93 50 push eax :00402A94 57 push edi * Reference To: MFC42.MFC42:NoName0124, Ord:16E0h | :00402A95 E84E130000 Call 00403DE8 :00402A9A 47 inc edi :00402A9B 83FF09 cmp edi, 00000009 :00402A9E 7EE7 jle 00402A87 :00402AA0 8B4E60 mov ecx, dword ptr [esi+60] =========================================================================== ECX now points to RegName that you entered, I entered '+Sync' =========================================================================== :00402AA3 8D7E60 lea edi, dword ptr [esi+60] :00402AA6 51 push ecx * Reference To: KERNEL32.lstrlenA, Ord:02A1h | :00402AA7 FF15CC734000 Call dword ptr [004073CC] ;Get Length :00402AAD 83F803 cmp eax, 00000003 ;Is it 3 or more :00402AB0 0F8CE5020000 jl 00402D9B ;No, beggar off :00402AB6 8B17 mov edx, dword ptr [edi] :00402AB8 8BCE mov ecx, esi :00402ABA 8A4201 mov al, byte ptr [edx+01] ;Load 2nd char of RegName :00402ABD 83E07F and eax, 0000007F :00402AC0 50 push eax ;pass 2nd to call :00402AC1 E84A030000 call 00402E10 =========================================================================== The call above 'cleans' the character, turning it into one of the valid letters which appear on the grid. See the code for this subroutine in the C code, it simply adds/subtracts 10 until in the right range =========================================================================== :00402AC6 8D0C80 lea ecx, dword ptr [eax + 4*eax] :00402AC9 8D04CE lea eax, dword ptr [esi + 8*ecx] :00402ACC 8B8CCE44F6FFFF mov ecx, dword ptr [esi + 8*ecx -000009BC] =========================================================================== Here we must take a small sidebar. When you create a checkbox in windows, a 1 word space of memory is set aside to hold the status of the box. There may be a reason Micro$oft used 4 bytes to hold a boolean value, but I sure don't know what it is. Let's think (yes I said think) a little about this little feature Micro$oft has included for us. A boolean value (TRUE or FALSE) can be stored in 1 bit. This means we have 21 Letters * 10 Numbers = 210 boolean values that can be stored in 210 bits. (210 bits)/8 =27 bytes could have been used to store the entire contents of the checkbox grid. However, Micro$oft used 21*10*4 = 840 bytes! They used 31 times as much memory as was necessary, an increase of over 3000% and we wonder why we are required to buy 32mb of ram. Well I have 21 Letters by 10 numbers, so that is 210 of these words set aside. They begin at DS:63EFBD, you can check this by setting a break in the code (right around 402AC1 will be fine) and checking box A-0, the first element in the array. Hit the 'register' button and when you break check out DS:63EFBD. This word should be set to 1 (DS:63EFC0 should be 01). You will also notice that they are ordered sequentally down the columns. So A-0 is the first word in the array, A-1 is the second etc. Allright, now we see that the mov statement above loads from this array. Put in '+Sync' as your name so that you can follow the next part. Trace up until 402ACC and then look at ECX. It should be 63F294 which is (63F294 - 63EFBD) = 2D7 bytes from the beginning. This means that there are 2D7 / 4 = B5 elements before this one, making it the B6th or 182th in decimal. Okay, there are 10 elements in each column so to figure out which row we are in we divide where we are at by 10. 182 / 10 = 18 rem 2, so we are in the 19th column, 2nd box down. This happens to be S-1. It is the 19th column because there are 18 complete columns before it, plus 2 boxes. Let's step back and look at this. We took the 2nd character of the name you typed in (cleaned to be in range) and forced a check to be in the row 1. The check to see if you checked the correct box is below. ============================================================================= :00402AD3 85C9 test ecx, ecx ;is it checked? :00402AD5 750A jne 00402AE1 ;yes, jmp over :00402AD7 C74424300E000000 mov [esp + 30], 0000000E ;no, alter RegFlag[1] =========================================================================== If any of the RegFlag's are altered then the check at the end will not work, so you want to jump over anything that alters them. =========================================================================== :00402ADF EB0A jmp 00402AEB * Referenced by a Jump at Address :00402AD5(C) | :00402AE1 C78090F9FFFF01000000 mov dword ptr [ebx+FFFFF990], 00000001 * Referenced by a Jump at Address :00402ADF(U) | :00402AEB 8B07 mov eax, dword ptr [edi] ;Point to Name :00402AED 8A10 mov dl, byte ptr [eax] ;dl=first char :00402AEF 8A4802 mov cl, byte ptr [eax+02] ;cl=third char :00402AF2 8A4001 mov al, byte ptr [eax+01] ;al=second char :00402AF5 83E27F and edx, 0000007F :00402AF8 83E17F and ecx, 0000007F :00402AFB 83E07F and eax, 0000007F :00402AFE 03D1 add edx, ecx ;add 1st and 3rd :00402B00 8BCE mov ecx, esi :00402B02 03D0 add edx, eax ;add 2nd to sum :00402B04 52 push edx :00402B05 E806030000 call 00402E10 ;clean (1st+2nd+3rd) :00402B0A 8D0C80 lea ecx, dword ptr [eax + 4*eax] :00402B0D 8D04CE lea eax, dword ptr [esi + 8*ecx] :00402B10 8B8CCE48F6FFFF mov ecx, dword ptr [esi + 8*ecx - 000009B8] =========================================================================== Much as before we can determine what row needs to have a check in based on the cleaned sum of the first 3 characters of the name. I go through it again. When you get to 402b10 ECX is loaded from 63F1A8 if your first 3 characters are '+Sy' as mine were. That means that there are (63F1A8 - 63EFBD) = 1EB bytes or 1EB/4 = 7A words (elements) ahead of it making it number 7B or the 123 element in decimal. This means that there are 123/10 = 12 row with 3 left over (3rd one down) ahead of it. This means that when you take the sum of the first 3 chars, clean it into a letter between A and U, you must have a check in that column in row 2(which is the 3rd one down). In my case with '+Sy' the 13th row is column is produced by this algorithm, which is 'M' so M-2 must be checked. =========================================================================== :00402B17 85C9 test ecx, ecx :00402B19 750F jne 00402B2A :00402B1B C744243423000000 mov [esp + 34], 00000023 ;Alter RegFlag[2] :00402B23 BD01000000 mov ebp, 00000001 :00402B28 EB0B jmp 00402B35 * Referenced by a Jump at Address :00402B19(C) | :00402B2A BD01000000 mov ebp, 00000001 :00402B2F 89A894F9FFFF mov dword ptr [eax+F994], ebp * Referenced by a Jump at Address :00402B28(U) | :00402B35 8B86F4020000 mov eax, dword ptr [esi+02F4] =========================================================================== (63F24C-63EFB)/4=A3 or 163rd element is loaded here (notice it does NOT depend at all on what you typed in). I will skip the math, this means column 17, row 3 must be checked. This is the 'Q' Column. So every valid code irregardless of the name you type as Q-3 checked. =========================================================================== :00402B3B 85C0 test eax, eax :00402B3D 750A jne 00402B49 :00402B3F C744243830000000 mov [esp + 38], 00000030 :00402B47 EB06 jmp 00402B4F * Referenced by a Jump at Address :00402B3D(C) | :00402B49 89AE40060000 mov dword ptr [esi+0640], ebp * Referenced by a Jump at Address :00402B47(U) | :00402B4F 8B17 mov edx, dword ptr [edi] :00402B51 8BCE mov ecx, esi :00402B53 8A02 mov al, byte ptr [edx] ;Load 1st Char :00402B55 83E07F and eax, 0000007F :00402B58 50 push eax :00402B59 E8B2020000 call 00402E10 ;Clean it :00402B5E 8D48C2 lea ecx, dword ptr [eax-3E] :00402B61 8D0C89 lea ecx, dword ptr [ecx + 4*ecx] :00402B64 833CCE00 cmp dword ptr [esi + 8*ecx], 00000000 =========================================================================== Same as above, except only first character is used. This means 1st character cleaned must be on row 4. =========================================================================== :00402B68 750A jne 00402B74 :00402B6A C744243013000000 mov [esp + 30], 00000013 :00402B72 EB0A jmp 00402B7E * Referenced by a Jump at Address :00402B68(C) | :00402B74 8D1480 lea edx, dword ptr [eax + 4*eax] :00402B77 89ACD69CF9FFFF mov dword ptr [esi + 8*edx - 00000664], ebp * Referenced by a Jump at Address :00402B72(U) | :00402B7E 8B07 mov eax, dword ptr [edi] :00402B80 8A4801 mov cl, byte ptr [eax+01] ;Load 2nd char :00402B83 83E17F and ecx, 0000007F :00402B86 51 push ecx :00402B87 8BCE mov ecx, esi :00402B89 E882020000 call 00402E10 ;Clean it :00402B8E 8D48C2 lea ecx, dword ptr [eax-3E] :00402B91 8D1489 lea edx, dword ptr [ecx + 4*ecx] =========================================================================== As +Orc would say, same old soup. 2nd character cleaned also needs to be on line 4. =========================================================================== :00402B94 833CD600 cmp dword ptr [esi + 8*edx], 00000000 :00402B98 750A jne 00402BA4 :00402B9A C744243412000000 mov [esp + 34], 00000012 :00402BA2 EB0A jmp 00402BAE * Referenced by a Jump at Address :00402B98(C) | :00402BA4 8D0480 lea eax, dword ptr [eax + 4*eax] :00402BA7 89ACC69CF9FFFF mov dword ptr [esi + 8*eax - 00000664], ebp * Referenced by a Jump at Address :00402BA2(U) | :00402BAE 8B0F mov ecx, dword ptr [edi] :00402BB0 8A5102 mov dl, byte ptr [ecx+02] ;Load 3rd char :00402BB3 8BCE mov ecx, esi :00402BB5 83E27F and edx, 0000007F :00402BB8 52 push edx :00402BB9 E852020000 call 00402E10 ;Clean it :00402BBE 8D48C2 lea ecx, dword ptr [eax-3E] :00402BC1 8D0C89 lea ecx, dword ptr [ecx + 4*ecx] ============================================================================ Same soup again! 3rd cleaned must be on line 4. Remember that this is the same line that the 1st and 2nd must be on. This means that if the first 3 characters are the same, only 1 check will satisfy all three conditions, but if they are different 3 checks are needed. This satisfies one of the hints I gave originally. (number of checks can vary) ============================================================================ :00402BC4 833CCE00 cmp dword ptr [esi + 8*ecx], 00000000 :00402BC8 750A jne 00402BD4 :00402BCA C744243811000000 mov [esp + 38], 00000011 :00402BD2 EB0A jmp 00402BDE * Referenced by a Jump at Address :00402BC8(C) | :00402BD4 8D1480 lea edx, dword ptr [eax + 4*eax] :00402BD7 89ACD69CF9FFFF mov dword ptr [esi + 8*edx - 00000664], ebp * Referenced by a Jump at Address :00402BD2(U) | :00402BDE 8B07 mov eax, dword ptr [edi] :00402BE0 33C9 xor ecx, ecx ;Start at 0 :00402BE2 8B50F8 mov edx, dword ptr [eax-08] :00402BE5 3BD5 cmp edx, ebp ;done yet? :00402BE7 7C10 jl 00402BF9 ;yes, jmp :00402BE9 40 inc eax * Referenced by a Jump at Address :00402BF2(C) | :00402BEA 0FBE68FF movsx ebp, byte ptr [eax-01] ;load char from name :00402BEE 03CD add ecx, ebp ;add to ecx :00402BF0 40 inc eax ;point to next char :00402BF1 4A dec edx :00402BF2 75F6 jne 00402BEA :00402BF4 BD01000000 mov ebp, 00000001 * Referenced by a Jump at Address :00402BE7(C) | :00402BF9 6A45 push 00000045 :00402BFB 51 push ecx * Reference To: MSVCRT.div, Ord:0243h | :00402BFC FF1514774000 Call dword ptr [00407714] ;This call divides ;the contents of ECX ;by 69 (45h) and puts ;the reult in AX :00402C02 83C408 add esp, 00000008 :00402C05 8BCE mov ecx, esi :00402C07 89442424 mov dword ptr [esp + 24], eax :00402C0B 52 push edx :00402C0C E8FF010000 call 00402E10 ;Clean it :00402C11 8D0480 lea eax, dword ptr [eax + 4*eax] :00402C14 8B8CC654F6FFFF mov ecx, dword ptr [esi + 8*eax - 000009AC] :00402C1B 8D04C6 lea eax, dword ptr [esi + 8*eax] ============================================================================== Notice the code above. It sums up the ASCII values of all the characters in the name you entered. Then the call at 402BFC: divides this sum by 45h (trace into it yourself to see how this is done using the Micro$oft Visual C Runtime). I'll skip the math this time, but just the same as before we find that this sum/45h and cleaned to the right range gives us a letter, and it must go on line 5. ============================================================================== :00402C1E 85C9 test ecx, ecx :00402C20 750A jne 00402C2C :00402C22 C744243044000000 mov [esp + 30], 00000044 :00402C2A EB06 jmp 00402C32 * Referenced by a Jump at Address :00402C20(C) | :00402C2C 89A8A0F9FFFF mov dword ptr [eax+F9A0], ebp * Referenced by a Jump at Address :00402C2A(U) | :00402C32 8B0F mov ecx, dword ptr [edi] :00402C34 8A4102 mov al, byte ptr [ecx+02] ;Load 3rd char :00402C37 8BCE mov ecx, esi :00402C39 83E07F and eax, 0000007F :00402C3C 8D1440 lea edx, dword ptr [eax + 2*eax] ;Notice that this puts 3*EAX in EDX :00402C3F D1E2 shl edx, 1 ;Mult. by 2 :00402C41 52 push edx :00402C42 E8C9010000 call 00402E10 ;Clean it :00402C47 8D0480 lea eax, dword ptr [eax + 4*eax] :00402C4A 8B8CC658F6FFFF mov ecx, dword ptr [esi + 8*eax - 000009A8] :00402C51 8D04C6 lea eax, dword ptr [esi + 8*eax] ============================================================================== Notice we took the 3rd charcater, multiplied by 3, multiplied by 2 then cleaned it. This is the same as multipliying by 6 (which is how it is coded originally in the C code). The letter this gives has a check in it in row 6, again see the math above for how to figure this out. ============================================================================== :00402C54 85C9 test ecx, ecx :00402C56 750A jne 00402C62 :00402C58 C74424341B000000 mov [esp + 34], 0000001B :00402C60 EB06 jmp 00402C68 * Referenced by a Jump at Address :00402C56(C) | :00402C62 89A8A4F9FFFF mov dword ptr [eax+F9A4], ebp * Referenced by a Jump at Address :00402C60(U) | :00402C68 8B07 mov eax, dword ptr [edi] :00402C6A 8A08 mov cl, byte ptr [eax] ;Load 1st char :00402C6C 8A5002 mov dl, byte ptr [eax+02] ;Load 3rd char :00402C6F 83E17F and ecx, 0000007F :00402C72 83E27F and edx, 0000007F :00402C75 0FAFCA imul ecx, edx ;1st * 3rd :00402C78 51 push ecx :00402C79 8BCE mov ecx, esi :00402C7B E890010000 call 00402E10 ;Clean it :00402C80 8D0480 lea eax, dword ptr [eax + 4*eax] :00402C83 8B8CC65CF6FFFF mov ecx, dword ptr [esi + 8*eax - 000009A4] :00402C8A 8D04C6 lea eax, dword ptr [esi + 8*eax] ============================================================================== Same as all the rest, 1st char multiplied by 3rd char, cleaned on line 7 ============================================================================== :00402C8D 85C9 test ecx, ecx :00402C8F 750A jne 00402C9B :00402C91 C74424383D000000 mov [esp + 38], 0000003D :00402C99 EB06 jmp 00402CA1 * Referenced by a Jump at Address :00402C8F(C) | :00402C9B 89A8A8F9FFFF mov dword ptr [eax+F9A8], ebp * Referenced by a Jump at Address :00402C99(U) | :00402CA1 8B0F mov ecx, dword ptr [edi] :00402CA3 8A11 mov dl, byte ptr [ecx] ;Load 1st char :00402CA5 8BCE mov ecx, esi :00402CA7 83E27F and edx, 0000007F :00402CAA 83EA04 sub edx, 00000004 ;Subtract 4 :00402CAD 52 push edx :00402CAE E85D010000 call 00402E10 ;Clean it :00402CB3 8D0480 lea eax, dword ptr [eax + 4*eax] :00402CB6 BA38000000 mov edx, 00000038 :00402CBB 8B8CC660F6FFFF mov ecx, dword ptr [esi + 8*eax - 000009A0] :00402CC2 8D04C6 lea eax, dword ptr [esi + 8*eax] ============================================================================== It's amazing, every check is done the same way. Once you have cracked one, you've cracked them all. This one takes the first character and subtracts 4 from it, cleans it to find a valid letter. The check must go with that letter and in row 8 ============================================================================== :00402CC5 85C9 test ecx, ecx :00402CC7 7506 jne 00402CCF :00402CC9 89542430 mov dword ptr [esp + 30], edx :00402CCD EB06 jmp 00402CD5 * Referenced by a Jump at Address :00402CC7(C) | :00402CCF 89A8ACF9FFFF mov dword ptr [eax+F9AC], ebp * Referenced by a Jump at Address :00402CCD(U) | :00402CD5 8B865C030000 mov eax, dword ptr [esi+035C] ============================================================================== Look at the line above. ESI holds 63EF58 (as it has the whole time), which means we are loading from 63EF58+35C = 63f2b4. We can calculate this as we did before. We will first subtract the starting point of the table 63F2B4 - 63EFBD = 2f7 But, there are 4 bytes ber item in the table so there are 2F7/4 = BD items in the array befor it. BD is 189 in decimal so, it is the 190th checkbox. This is the at S-9. Again this does not depend on the name you enter, it is in every valid code. ============================================================================== :00402CDB 85C0 test eax, eax :00402CDD 750A jne 00402CE9 :00402CDF C74424342F000000 mov [esp + 34], 0000002F :00402CE7 EB06 jmp 00402CEF * Referenced by a Jump at Address :00402CDD(C) | :00402CE9 89AEA8060000 mov dword ptr [esi+06A8], ebp * Referenced by a Jump at Address :00402CE7(U) | :00402CEF 8B8680010000 mov eax, dword ptr [esi+0180] ============================================================================== This is just like the check above, it requires an 'H' on line 0 ============================================================================== :00402CF5 85C0 test eax, eax :00402CF7 750A jne 00402D03 :00402CF9 C744243830000000 mov [esp + 38], 00000030 :00402D01 EB06 jmp 00402D09 * Referenced by a Jump at Address :00402CF7(C) | :00402D03 89AECC040000 mov dword ptr [esi+04CC], ebp * Referenced by a Jump at Address :00402D01(U) | :00402D09 8B86B8000000 mov eax, dword ptr [esi+00B8] ============================================================================== This is just like the check above, it requires an 'C' on line 0 ============================================================================== :00402D0F 85C0 test eax, eax :00402D11 750A jne 00402D1D :00402D13 C74424303B000000 mov [esp + 30], 0000003B :00402D1B EB06 jmp 00402D23 * Referenced by a Jump at Address :00402D11(C) | :00402D1D 89AE04040000 mov dword ptr [esi+0404], ebp * Referenced by a Jump at Address :00402D1B(U) | :00402D23 8B8688030000 mov eax, dword ptr [esi+0388] ============================================================================== This is just like the check above, it requires an 'U' on line 0 ============================================================================== :00402D29 85C0 test eax, eax :00402D2B 750A jne 00402D37 :00402D2D C744243440000000 mov [esp + 34], 00000040 :00402D35 EB06 jmp 00402D3D * Referenced by a Jump at Address :00402D2B(C) | :00402D37 89AED4060000 mov dword ptr [esi+06D4], ebp * Referenced by a Jump at Address :00402D35(U) | :00402D3D 8BC5 mov eax, ebp :00402D3F 8D4E68 lea ecx, dword ptr [esi+68] * Referenced by a Jump at Address :00402D5C(C) | :00402D42 8BA94C030000 mov ebp, dword ptr [ecx+034C] :00402D48 3B29 cmp ebp, dword ptr [ecx] :00402D4A 7407 je 00402D53 :00402D4C 8D6864 lea ebp, dword ptr [eax+64] :00402D4F 896C2434 mov dword ptr [esp + 34], ebp * Referenced by a Jump at Address :00402D4A(C) | :00402D53 40 inc eax :00402D54 83C104 add ecx, 00000004 :00402D57 3DD2000000 cmp eax, 000000D2 :00402D5C 7EE4 jle 00402D42 :00402D5E 837C243045 cmp dword ptr [esp + 30], 00000045 ;Is RegFlag[1] unchanged ? (still 69 or 45h) :00402D63 7404 je 00402D69 ;yes, jump ahead good guy :00402D65 89542434 mov dword ptr [esp + 34], edx ;no, alter RegFlag[2] * Referenced by a Jump at Address :00402D63(C) | :00402D69 837C243460 cmp dword ptr [esp + 34], 00000060 ;RegFlag[2] still unchanged? :00402D6E 7408 je 00402D78 ;yes, jmp ahead good guy :00402D70 C74424382B000000 mov [esp + 38], 0000002B ;no, alter RegFlag[3] * Referenced by a Jump at Address :00402D6E(C) | :00402D78 837C243863 cmp dword ptr [esp + 38], 00000063 ;is RegFlag[3] still 99 or 63h? :00402D7D 7507 jne 00402D86 ;nope, beggar off ============================================================================= Note to those who sent in answers with several pathes in them. This is the ONLY place that a patch would be necessary. Change the 7507 above to a 7500 and everything would be fine. (the name would still be forced to be at least 3 chars still however). Nice and clean patch, no NOPs and only 1 byte changed ============================================================================= :00402D7F 8D4C2410 lea ecx, dword ptr [esp + 10] ;yep, register good guy :00402D83 51 push ecx :00402D84 EB05 jmp 00402D8B * Referenced by a Jump at Address :00402D7D(C) | :00402D86 8D54240C lea edx, dword ptr [esp + 0C] ;Point to "Unregistered" :00402D8A 52 push edx * Referenced by a Jump at Address :00402D84(U) | :00402D8B 8BCF mov ecx, edi * Reference To: MFC42.MFC42:NoName0125, Ord:035Ah | :00402D8D E85C100000 Call 00403DEE ;Call to UpdateData to put the text in the window :00402D92 6A00 ------------------------------------------------------------------------------ Below is a short summary of what the requirements are. The right column will provide a decimal number, the ASCII code for the letter above the column you must check. Line 1 - 2nd char cleaned Line 2 - (1st + 2nd + 3rd) cleaned Line 3 - Q Line 4 - 1st char cleaned Line 4 - 2nd char cleaned Line 4 - 3rd char cleaned Line 5 - Remainder of (Sum of all chars / 69) cleaned Line 6 - (6 * 3rd char) cleaned Line 7 - (1st * 3rd) cleaned Line 8 - (1st - 4) cleaned Line 9 - S Line 0 - H Line 0 - C Line 0 - U As always, comments are welcome. +Sync (c) +Sync 1997. All rights reserved
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