OKay so what it does is take the character XOR it with the corresponding byte in the table at DAT_00... add that to a running total then return until tevery character is processed.

but there is one more function before it

this one

so the date have READ context

okay so what the function, which I suppose ... is

checksum = sum over i of (input[i] XOR table[i])

not sure

my maths might not be correct tho

param_1[0] = pointer to the string's character buffer

param_1[1]=lenght of the string

00104028  81                                db                      81h
                   00104029  00                                ??                       00h
                   0010402a  00                                ??                       00h
                   0010402b  00                                ??                       00h
                   0010402c  ab                                ??                       ABh
                   0010402d  00                                ??                       00h
                   0010402e  00                                ??                       00h
                    0010402f  00                                ??                       00h
                   00104030  fe                                 ??                       FEh
                   00104031  00                                ??                       00h
                   00104032  00                                ??                       00h
                   00104033  00                                ??                       00h
                   00104034  7b                                ??                       7Bh    {
                   00104035  00                                ??                       00h
                   00104036  00                                ??                       00h

so this are the first 15 byte now gotta find a way

so after checking the table is not an array of char but an array of unit(4 bit each) they are 32-bit integers

So okay that maths is this, which mathematically would work but idk

                                                                   DAT_00104020                                                                                    XREF[2]:               FUN_001014b0:001014c4(*), 
                                                                                                                                                                                                                 FUN_001014b0:001014d5(R)  
                   00104020  04 00 00 00               undefined4      00000004h
                                                                   DAT_00104024                                                                                    XREF[1]:               FUN_001014b0:001014d5(R)  
                   00104024  4f 00 00 00                undefined4      0000004Fh
                   00104028  81                                db                      81h
                   00104029  00                                ??                       00h
                   0010402a  00                                ??                       00h
                   0010402b  00                                ??                       00h
                   0010402c  ab                                ??                       ABh
                   0010402d  00                                ??                       00h
                   0010402e  00                                ??                       00h
                    0010402f  00                                ??                       00h

But there are 2 XREF sooo wait ...

so still this only computes number from whatever string I typed

undefined8 FUN_001011f0(void) {
  int iVar1;
  ostream *poVar2;
  long in_FS_OFFSET;
  int local_7c;
  undefined1 *local_78;
  long local_70;
  undefined1 local_68 [16];
  string local_58 [40];
  long local_30;
  
  local_30 = *(long *)(in_FS_OFFSET + 0x28);
  local_78 = local_68;
  local_68[0] = 0;
  local_70 = 0;
  poVar2 = std::operator<<((ostream *)std::cout,"Enter a string of characters (no spaces): ");
  FUN_00101430(poVar2);
  std::operator>>((istream *)std::cin,(string *)&local_78);
  if (5 < local_70 - 5U) {
    std::operator<<((ostream *)std::cout,"Bro, what are you trying to do?");
    FUN_00101430();
                    /* WARNING: Subroutine does not return */
    exit(0);
  }
  poVar2 = std::operator<<((ostream *)std::cout,"Enter correct number (no spaces): ");
  FUN_00101430(poVar2);
  std::istream::operator>>((istream *)std::cin,&local_7c);
  std::__cxx11::string::string(local_58,(string *)&local_78);
  iVar1 = FUN_001014b0(local_58);
  std::__cxx11::string::_M_dispose();
  if (local_7c == iVar1) {
    poVar2 = std::operator<<((ostream *)std::cout,"OMG! You did it! :3");
  }
  else {
    poVar2 = std::operator<<((ostream *)std::cout,"Send help pls.");
  }
  FUN_00101430(poVar2);
  std::__cxx11::string::_M_dispose();
  if (local_30 == *(long *)(in_FS_OFFSET + 0x28)) {
    return 0;
  }
                    /* WARNING: Subroutine does not return */
  __stack_chk_fail();
}

so which means I missed smthing here

so I finalized it to this code that's the logic I suppose if you enter any character longer than 5 it exits with that message and then the next one is the number you type must be equal to the checksum of your string..

the check sum is this the comments for simplification ...

time to try it

so wait

ghidra did unsigned substraction so .... local_70 is the string length, the expression length_70 - 5U is unsigned

this underflows to a huge number, which is >5, so the real condition is local_70 <5