CHAPTER 78. DONGLES CHAPTER 78. DONGLES
seg030:017F 89 46 FE mov [bp+var_2], ax
seg030:0182 8B C6 mov ax, si
seg030:0184 6B C0 12 imul ax, 18
seg030:0187 66 0F BF C0 movsx eax, ax
seg030:018B 66 8B 56 FA mov edx, [bp+var_6]
seg030:018F 66 03 D0 add edx, eax
seg030:0192 66 89 16 D8+ mov _expiration, edx
seg030:0197 8B DE mov bx, si
seg030:0199 6B DB 1B imul bx, 27
seg030:019C 8B 87 D5 3C mov ax, _Q._A[bx]
seg030:01A0 3B 46 FE cmp ax, [bp+var_2]
seg030:01A3 74 05 jz short loc_35B0A
seg030:01A5 B8 01 00 mov ax, 1
seg030:01A8 EB 02 jmp short loc_35B0C
seg030:01AA
seg030:01AA loc_35B0A: ; CODE XREF: check_dongle+1Fj
seg030:01AA ; check_dongle+5Ej
seg030:01AA 33 C0 xor ax, ax
seg030:01AC
seg030:01AC loc_35B0C: ; CODE XREF: check_dongle+63j
seg030:01AC 5E pop si
seg030:01AD C9 leave
seg030:01AE CB retf
seg030:01AE check_dongle endp
Since the routine can be called very frequently, e.g., before the execution of each important software feature, and accessing
the dongle is generally slow (because of the slow printer port and also slowMCUin the dongle), they probably added a way
to skip some dongle checks, by checking the current time in thebiostime()function.
Theget_rand() function uses the standard C function:
seg030:01BF get_rand proc far ; CODE XREF: check_dongle+25p
seg030:01BF
seg030:01BF arg_0 = word ptr 6
seg030:01BF
seg030:01BF 55 push bp
seg030:01C0 8B EC mov bp, sp
seg030:01C2 9A 3D 21 00+ call _rand
seg030:01C7 66 0F BF C0 movsx eax, ax
seg030:01CB 66 0F BF 56+ movsx edx, [bp+arg_0]
seg030:01D0 66 0F AF C2 imul eax, edx
seg030:01D4 66 BB 00 80+ mov ebx, 8000h
seg030:01DA 66 99 cdq
seg030:01DC 66 F7 FB idiv ebx
seg030:01DF 5D pop bp
seg030:01E0 CB retf
seg030:01E0 get_rand endp
So the text string is selected randomly, passed into the dongle, and then the result of the hashing is compared with the
correct value.
The text strings seem to be constructed randomly as well, during software development.
And this is how the main dongle checking function is called:
seg033:087B 9A 45 01 96+ call check_dongle
seg033:0880 0B C0 or ax, ax
seg033:0882 74 62 jz short OK
seg033:0884 83 3E 60 42+ cmp word_620E0, 0
seg033:0889 75 5B jnz short OK
seg033:088B FF 06 60 42 inc word_620E0
seg033:088F 1E push ds
seg033:0890 68 22 44 push offset aTrupcRequiresA ; "This Software Requires a Software ⤦
ÇLock\n"
seg033:0893 1E push ds
seg033:0894 68 60 E9 push offset byte_6C7E0 ; dest
seg033:0897 9A 79 65 00+ call _strcpy
seg033:089C 83 C4 08 add sp, 8
seg033:089F 1E push ds
seg033:08A0 68 42 44 push offset aPleaseContactA ; "Please Contact ..."
seg033:08A3 1E push ds