I learned this trick writing shellcode - the shellcode has to be null byte (0x00) free, or it will terminate and not progress past the null byte, since it is th

I learned this trick writing shellcode - the shellcode has to be null byte (0x00) free, or it will terminate and not progress past the null byte, since it is the string terminator. of course, when you xor something with itself, the result is zero. the byte code generated by the instruction xor eax, eax doesn't contain null bytes, whereas mov eax, 0 does.