encrypted binary integrity chacking with anti debug POC

;// ------------------------------------------------------------------------------
;// THE BEER-WARE LICENSE (Revision 43):
;// <aaronryool@gmail.com> wrote this file. As long as you retain this notice you
;// can do whatever you want with this stuff. If we meet some day, and you think
;// this stuff is worth it, you can buy me a beer in return
;// ------------------------------------------------------------------------------

; for a full write up on this, go here:
; https://www.hackthissite.org/forums/viewtopic.php?f=156&t=12300&p=88305

[bits 32]
section .text
global _start

org 0x08048000
ehdr:                                      ; Elf32_Ehdr
    db 0x7F, "ELF", 1, 1, 1, 0         ;   e_ident
    times 8 db      0
    dw 2                               ;   e_type
    dw 3                               ;   e_machine
    dd 1                               ;   e_version
    dd _start                          ;   e_entry
    dd phdr - $$                       ;   e_phoff
    dd 0                               ;   e_shoff
    dd 0                               ;   e_flags
    dw ehdrsize                        ;   e_ehsize
    dw phdrsize                        ;   e_phentsize
    dw 1                               ;   e_phnum
    dw 0                               ;   e_shentsize
    dw 0                               ;   e_shnum
    dw 0                               ;   e_shstrndx
    ehdrsize equ $ - ehdr

phdr:                                      ; Elf32_Phdr
    dd 1                               ;   p_type
    dd 0                               ;   p_offset
    dd $$                              ;   p_vaddr
    dd $$                              ;   p_paddr
    dd filesize                        ;   p_filesz
    dd filesize                        ;   p_memsz
    dd 7                               ;   p_flags
    dd 0x1000                          ;   p_align
    phdrsize equ $ - phdr
_start:
    jmp code
begin:
    pop esi             ; pop the address of our data
    mov ecx, 36         ; set loop count to the size of the encrypted data
    xor eax, eax
    xor ebx, ebx
decode:
    mov al, byte [_start+ebx]       ; load character from key into al
    xor byte [esi], al              ; xor the key with the encrypted code
    inc esi                         ; increment our address
    inc ebx                         ; increment our secondary counter
loop decode
    jmp hello
    db 0x9c, 0xc8, 0x96, 0x5a, 0xb4, 0x8e, 0x5f ; garbage filler because the key code is smaller than 36 bytes
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; encrypted code:
code:
    call begin
hello:
    db 0x00,0x0e,0x07,0x88,0xe4,0x31,0xdb,0x31
    db 0xe3,0x70,0x35,0x68,0x8b,0x31,0x58,0x4d
    db 0x84,0xe3,0x21,0xee,0xac,0xbc,0x1d,0x0b
    db 0x83,0x69,0xf0,0xa4,0xf9,0x7a,0xc3,0xe1
    db 0x2d,0x84,0xb8,0xf5
;_start:
;   jmp hi
;main:
;   pop ecx
;   xor eax, eax
;   xor ebx, ebx
;   xor edx, edx
;   mov al, 0x4
;   mov bl, 1
;   mov dl, 12
;   int 0x80
;   jmp end
;hi:
;   call main
;   db "hello world", 0xa
;end:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; exit
    xor ebx, ebx
    xor eax, eax
    inc eax
    int 0x80

filesize equ $ - $$