Logika Assembly 32 bit (Bahasa Rakitan)

lagi bikin b0tn3t buat prolonged/permanent dns attack eh tangan gue gatel mao nyambi 
maenan  dulu ah biar gak puyeng (deface and ddos is common attacks, we 
don't play it anymore, we'are goin to play with prolonged / possible permanent dns attack soon)

[b]logika and[/b]
[code]
;contoh rutin utama:
mov eax,23h
mov ebx,23h 
and eax,ebx
[/code]
logika ini mengharuskan kondisi keduanya terpenuhi jika ya maka true(1) 
jika tidak maka false (0).
contoh kode asm 32 bit dengan logika and:

[code]
global _start
_start:
mov eax,23h
mov ebx,23h
and eax,ebx
[/code]

assemble dan linker:

[code]
root@mywisdom-Vostro1310:/home/mywisdom/asm# nasm -f elf and.asm -g
root@mywisdom-Vostro1310:/home/mywisdom/asm# ld -o and and.o
[/code]

Ok sekarang kita analisis hasil statemen di atas dg gdb:

[code]
root@mywisdom-Vostro1310:/home/mywisdom/asm# gdb -q and
Reading symbols from /home/mywisdom/asm/and...done.
(gdb) run
Starting program: /home/mywisdom/asm/and 

Program received signal SIGSEGV, Segmentation fault.
0x0804806c in ?? ()
(gdb) i r
eax            0x23	35
ecx            0x0	0
edx            0x0	0
ebx            0x23	35
esp            0xbffff480	0xbffff480
ebp            0x0	0x0
esi            0x0	0
edi            0x0	0
eip            0x804806c	0x804806c
eflags         0x210202	[ IF RF ID ]
cs             0x73	115
ss             0x7b	123
ds             0x7b	123
es             0x7b	123
fs             0x0	0
gs             0x0	0
(gdb) 

[/code]

terlihat hasil logika and pada register eax:
eax -----   0x23 / 23h 

berikut ini cara kerja logika and tadi:
mov eax,23  --- register eax diisi 23 
mov ebx,23  --- register ebx diisi 23 

23  dikonvert ke biner adalah: 00100011

berikut ini  logika and :
[code]
------------
0 and 0 -> 0
1 and 0 -> 0
1 and 1 -> 1
-------------
[/code]

jadi:
[code]
00100011
00100011
_____________ (and)
00100011  = 23h 
[/code]

[b]Logika or[/b]
rutin utama:
[code]
;contoh rutin utama:
mov eax,50h
mov ebx,20h 
or eax,ebx
[/code]

logika ini gak musti kondisi keduanya terpenuhi dia udah bisa true (1)

contoh kode asm 32 bit dengan logika or:

[code]
global _start
_start:
mov eax,50h
mov ebx,20h
or eax,ebx
[/code]

assemble dan linker:

[code]
root@mywisdom-Vostro1310:/home/mywisdom/asm# nasm -f elf or.asm 
root@mywisdom-Vostro1310:/home/mywisdom/asm# ld -o or or.o
[/code]

analisis hasil dengan gdb:
[code]
root@mywisdom-Vostro1310:/home/mywisdom/asm# gdb -q or
Reading symbols from /home/mywisdom/asm/or...(no debugging symbols found)...done.
(gdb) r
Starting program: /home/mywisdom/asm/or 

Program received signal SIGSEGV, Segmentation fault.
0x0804806c in ?? ()
(gdb) i r
eax            0x70	112
ecx            0x0	0
edx            0x0	0
ebx            0x20	32
esp            0xbffff480	0xbffff480
ebp            0x0	0x0
esi            0x0	0
edi            0x0	0
eip            0x804806c	0x804806c
eflags         0x210202	[ IF RF ID ]
cs             0x73	115
ss             0x7b	123
ds             0x7b	123
es             0x7b	123
fs             0x0	0
gs             0x0	0
(gdb) 

[/code]

eax menjadi berisi 0x70  yg merupakan hasil or dg ebx

perhatikan rutin simple ini:
mov eax,50h ----> register eax diisi 50 hex 
mov ebx,20h ----> register ebx diisi 20 hex
or eax,ebx ----> lakukan logika or untuk reg eax dan ebx

itunganya gini:

0x50  = 01010000 -> dalam bilangan biner
0x20  = 00100000

logika dimulai:
[code]
01010000
00100000
_________(or)
01110000          ----------->>>> 0x70 

[/code]

keterangan logikanya:

0 or 0 = 0
1 or 0 = 1
1 or 1`= 1

[b]Logika XOR (Exclusive Or)[/b]
xor ==exclusive or , ini semua logika sama dengan or tapi bedanya klo 2 
kondisi true dia malah jadi false. check tis out:


contoh potongan xor:
[code]
global _start
_start:
mov eax,1h
mov ebx,2 h
xor eax,ebx
[/code]

oke simpan dg nama xor.asm lalu assemble dan linker 
[code]
nasm -f elf xor.asm -g
ld -o xor xor.o
[/code]

gdb:
[code]
root@mywisdom-Vostro1310:/home/mywisdom/asm# gdb -q xor
Reading symbols from /home/mywisdom/asm/xor...(no debugging symbols found)...done.
(gdb) r
Starting program: /home/mywisdom/asm/xor 

Program received signal SIGSEGV, Segmentation fault.
0x0804806c in ?? ()
(gdb) i r
eax            0x3	3
ecx            0x0	0
edx            0x0	0
ebx            0x2	2
esp            0xbffff480	0xbffff480
ebp            0x0	0x0
esi            0x0	0
edi            0x0	0
eip            0x804806c	0x804806c
eflags         0x210206	[ PF IF RF ID ]
cs             0x73	115
ss             0x7b	123
ds             0x7b	123
es             0x7b	123
fs             0x0	0
gs             0x0	0
(gdb) 

[/code]

hasil xor terlihat pada register eax yg menjadi  0x3 / 3 hexa  .
[code]
1  = 00000001
2  = 00000010
       ---------(xor)   
        00000011 == 0x3
[/code]

nih klo buat yg xor:
[code]
1 xor 1 equ 0
1 xor 0 equ 1
0 xor 0 equ 0
[/code]


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