Question

I am trying to make a password file where you enter the password and it shows you all your passwords. My current code is this, but it has an error:

.386
.model flat,stdcall
option casemap:none

include     \masm32\include\windows.inc
include     \masm32\include\kernel32.inc
include     \masm32\include\masm32.inc
includelib  \masm32\lib\kernel32.lib
includelib  \masm32\lib\masm32.lib

.data
        input   db 'Enter the password:',13,10,0
        string  db 'The passwords are:',0
        space db '       ',0
        pass1 db 'example password 1',0
        pass2 db 'example password 2',0
        pass3 db 'example password 3',0
        pass4 db 'example password 4',0
        ermsg db 'Incorrect Password. Exiting....',0
        count dd 0
            comp dd 13243546

.data?
        buffer db 100 dup(?)
.code
start:
_top:
        invoke StdOut,ADDR input
        invoke StdIn,ADDR buffer,100 ; receive text input
        cmp buffer, comp ;sorry for not pointing this out - this is line 32
        jz _next
        jmp _error
_next:
        invoke StdOut, ADDR string
        invoke StdOut, ADDR space
        invoke StdOut, ADDR pass1
        invoke StdOut, ADDR pass2
        invoke StdOut, ADDR pass3
        invoke StdOut, ADDR pass4
        invoke ExitProcess,0
_error:
        invoke StdOut, ADDR ermsg
        mov eax, 1
            mov count, eax
            cmp count, 3
            jz _exit
            jmp _top:
_exit:
            invoke ExitProcess, 0

This is the error:

 test.asm(32) : error a2070: invalid instruction operands

Why does that happen. I understand that the error is on line 32 but I don’t understand what the error is.

Answer 1

cmp is used to compare two bytes/words/dwords, not strings. So you’re basically asking it to compare the first four bytes of buffer to the four bytes of comp and using invalid syntax to do this.

To compare strings, you need to use cmps or a manual loop.

Additionally, comp should be declared as comp db '13243546', 0 . The way you declared it now makes it into a dword 00CA149A, which is equivalent to the C string "\x9A\x14\xCA" – quite complex to type 🙂