
TRƯỜNG ĐẠI HỌC MỎ - ĐỊA CHẤT

BÀI TẬP LỚN
AN TOÀN VÀ BẢO MẬT THÔNG TIN
 HỆ MÃ HÓA KHỐI DES

 !"#$%"
&'()*"
+!,
-&&
."#/"01
2314#5"
2-67
8797
+:;<=
>'? !))@"#"#ABC")D""# EFG,
H
IJA0"'51'!K*)L1'M"DFNFI1
OID0"'D"OP1Q')D)R)'L*AK/"OI"JA0"'?S"#F.)O*'L'?D"#LT"K()
JA5"U("#D3#0DV#B"0BK!U(WAX'*")Y01RB'P")R)'L*AK/"
OI"#XB'EK)R)'@"#'"JA0"'?S"#FZAF [)U\]0KW^L_'?C"1RB'P"
F [)'?ABZ"F'?D"#1@'? E"#11.)F4"L`@"#0"'D"VDF]BCA)aA
KZK*))]1')b)M#I,R,FNOIDK*U(0"'D"KOP1Q')Y0)R)'@"#'"
"3B)I1JA0"'?S"#"#B)"#'?c"C")X,'M'V-Q'1GS))P"L"#"
`D0S)FI1OID)D1d)FP)"BV]$(0'?C""Z"'I"#)R)'AQ''DR"'DR"
S)U\S)WR)UAX'K)R)1@"`D0S)`R)FN'3D?0)R)*1G]0VF.)
O*',I`NFM"L*1G]0`\1FN"e"L*1G]0`\f&g0'0
f")?B,'D"&'0"$0?$h1''?D"#U\)R)*1G]0`\F [)U^$d"#?"#?G
"X'KL"Z"'I"#)D?X'"ZA*1G]0`\`R)V
I. Tổng quan về hệ mã hóa khối

?D"#1Q'1GS)1G]0`\L"i"#'AQ''DR"1G]0F\Wj"#D3'F"#
'?C""i"#`\'@"#'")]F$WR)F4"gOLD)`hK!"i"#)ABN"FkWR)
F4"Vl"#3"1''AQ''DR"1G]0`\)]'NW^L_`\mO'UFaAKD
KOM""]'"`\mO'UcFaA?0VnAI'?e")ABN"Fk)o"U^$d"#'C1
1''01U\"i0`]0OP1Q'FN)RO*']0JAR'?e"V*)#I1G)p"#$q"?0
' b"#'(W^L_`k1G]0mO'U)r"#K!`]0FN'?IKZ`\mO'UOI"
?sO0"FaAV
N1G]0"i"#K/"OI")]F$K ['JARF$)Y0`\"# E'0U^$d"#
'AQ''DR"'tD1')b)M1G]0`\"DF]V
25"O*'K!1G]0`\L1G]0$o"#V-G]0$o"#L1K*)'?C"'>"#O'U
)Y0$o"#$iL*AKJAR'?e"OM"Fk'0BFk'tDJAR'?e"1G]0VAB
"C"U(,5"O*'#i00, b"#,R,"ZA``@"#?s?"#Ke1G]0
`\`D3'F"#'tD1')b)M"DF]'e)]'R)$d"#" 1', b"#,R,
1G]0$o"#V
nAR'?e"1G]0`\O0D#u1'AQ''DR"1G]0`_*AEK#I1G`_
*AE
-1
VI'AQ''DR"FZA'R)F"#LC"1'`\FaAKD"OP'U^$d"#1'
`]0`OP'FN)D?01'`\FaA?0"OP'V\K!OX'`v`]0"D#I1G
L1"# [))Y01G]0"#T0L
'?D"#F]-L`\'@"#'"K6L`]0OX'`vV
!1w`]06f6L1'DR"K4gUD"#R"h)Y0`\FaAKDV-w`]0UxWR)
F4"1'DR"K4'?D"#'k"#U\ `I"/"#V
$)Y0`\'@"#'"`_*AL"'@"#' E"#L)\F4"cyD.)m
OP'V-'U\'AQ''DR")]F$`\'0BFk" "#`@"#,kOM"VP"FM"
'? !)"i"#"/1#i0)Y0'Q,`z88'eF$yOP'' E"#F [)U^$d"#V
>F]'?cKZU0A'e`\mOP'F [)U^$d"#?"#?Gb"V?D"#)R))MF
1G]0`\'e"# E'0' E"#,IOkUA"#'C11'U\OP')DK/"OI"
g'M"#{",0$$"#hFNK/"OI")j0U\"#ABC"La")R)`\V-w)MF1G
]0)]F.)'P"`R)"0AKZL0"'?ABZ"LwgLw1G]0'?D"#`\"BI"

 c"#'!`\`R)h`I"/"#'?ABWAX'"#%A"C"K`I"/"#)\"#L3)R)
`NA'X")@"#`R)"0AV$'@"#' E"#)Y0`]0`L7yymm
8K7yOP'VDFM""/1y'emOP'LF$'\'NA)Y0`]0FN)]'N
)\"#L3'X")@"#`NA$AB*''D"OV
aAM')R)'AQ''DR"1G]0`\U^$d"#L.,FL.,L3)R)1Fb"#I"V
2 b"#,R,"B)o"F [)#SL1G]0`\L.,V-w)A`vL.,F [)#SL
1'Ko"#g?DA"$hK'@"#' E"#)R)'AQ''DR")]'>'!Ko"#V
|X'"ZA'AQ''DR"1G]0`\)]'P")X')Y013"#}tU'tL0B'k"#JAR'
b"L*'\"#'MKDR"K4VR)'",a"U^$d"#'?D"#'AQ''DR"L
)R)1'DR"S))R)1LD#)gF.)O*'L1~|h,'Mg&ODWhK)R)
, b"#,R,DR"K4V
ZA`*"FN1G]0`\0"'D"
• 6P)' !)`\,IFYL!"FN)\"#L3, b"#R"'X")@"#O•"#
, b"#,R,'\"#`CVAB"C"FZA"BUx$%"FM"'E#0"1G]0
'/"#LC"V
• 6@"##0"`]0'j))ZA$`]0,IFYL!"FN)\"#L3, b"#R"
'X")@"#O•"#K€')3"VAB"C"`]0,IFY"#•"FNK*)'3D`]0
,5",\KL A'?i`]0F [)$q$"#V
6'M'`M1'*1G]0`\,IFI1OID0BCA)aAU0A
• &(w"LD3"g)D"‚AUD"h&(,d'A)#i0OI"?sKOI"1G,I'()
U(,j)'3,FN#5B`]`/"K!K*)'e1JABLAQ''R11GV-\JA0"*
"B'\'"X'L,'ABM"V
• &(`AM)'R"g$‚‚AUD"h-wO')Y0OI"?sK`]0,0?I" c"#
LC")"#"ZAO')Y0OI"1G)"#'\'V
II. Chuẩn mã hóa dữ liệu khối DES
1. Mô tả sơ đồ mã hóa khối DES
f&L'AQ''DR"1G]0K!",A'L`\yO'DA',A')p"#L`\yO'V
6]01G]0)]F$7yO''()?0)P"WR)b",ILyO'K!)R)O'
cK4'?P)0M')Dm)]'MU^$d"#)D)R)O'`N1'?0'P")ƒ"L„V&\
`]0)Y0`@"##0"`]06L

7y
V
e"A…"1G]0$iL*Af&
AQ''DR"'()*"yKo"#V>`]0",A'6y`]0)D"mO'6

Ux
F [)U"?01w`]0'0B'MyO''"O'&

g)o"#SL,&

hF [)
)S"L(0`†)"#K)\F4"`_*A)A"#L&UxF [)U^$d"#VI"?sy
O'UxF [)U^$d"#)0'"0"^0+

 K|

VR)Ko"#)])j)"/"#
#\"#"0A"Q"",A'L+

K|

'>Ko"#'? !)KU"?0DA',A'L)R)
W5AO'+

K|

" U0A
+

‡|


ˆgh
|

‡+

‚g|

6

h'?D"#F]‚g|

6

h‡2g&gfg|

h 6

hhˆgh
?D"#F]
 L`_*A)Y0,€,'ABN"LD3'?>g~|h)Y00W5AO''tD
1D$ALDV
 1‚L1'1,'ABM"V
 fLDR"K41c?"#R"W3|

'>O''"mO'gF@`'X'
)I)R)O'UxF [)U^$d"#D.)1'O'UxF [)U^$d"#La"hV
 2LDR"K4)\F4"`R))Y0O'V
-'DR"K4O'`cFaAg2hF [)U^$d"#)DKo"#FaA'C"ˆU0AKo"#)A\
)r"#"^0'?RK,IUxF [)Fk"# [))D"0AK)A\)r"#W5A`M'JAI

UxF [)DR"K4O'La")A\OcDR"K4"# [))Y02g2hV
nAR'?e"#I1G$q"?0' b"#'(" "#K!)R)`]0)D"j"#$d"#KD)R)
Ko"#'?D"#'tD'j'("# [)L3V
]'Ne"$A"#Fb"#I"L,a"OC",I'?D"#1wKo"#gU0A`1c?"#
",A'O''"m`_'(yO'‰W5AmO'hUxF [)'()*"1''P"'DR"
'0B'M,d'A)`]0'?C"1w1'`_'('?D"#W5AmO'KU0AF]U^
$d"#1',€,)ABN"O')\F4"FN,5"O\L3)R)O')Y0)R)`_'(`M'
JAIe"'""C"DA',A'O'V
R)`]0)D"6

g)j0mO')Y06hF [)'P"O•"#)R)U^$d"#)R)OI"#
2K2g2t?1A'0'D"D)tKhV? !)'C"mO'g`
m
`
y
Š`
y
h)Y0
6O4O‹FgR,$d"#2hV7yO')o"L3F [)DR"K4K#R")D0OM"m
O'KU0AF]'?D"#yKo"#L.,)IKUxF [)JA0BD.)O'K
)R)`]0)D"mO'6

F [))S"'>`M'JAI)Y0K*)#€,0W5AK!"0AV
 KQB'0)]'N1@'I'D"O'AQ''DR"U"1Gf&$ !$3"#)@"#'j)
" U0A
?D"#F]
 1@'I,€,DR"K4)Y0)R)`\+

|


gŒŒ7hV
 ‚

1@'IK*)$r"#1‚K!`]06

gŒŒyhV
AQ''DR")'M'
",A'I"?s-‡1

1

Š1
y
`]0yO'6‡`

`

Š`
y
gO0D#u1)ImO'
)ƒ"LxK*)'C1O')ƒ"L„U0D)D)R)FD3"`]0mO')]U\O'LL„hV
A',A'OI"1GyO'‡)

)

Š)
y
V &"`]0)D"VP")R)`]0)D"'tD'AQ''DR"U"`]0)D"OC"
$ !
V g+


|

h•2g1

1

Š1
y
hg&^$d"#OI"#DR"K42FNDR"K4)R)O'
`M'JAI"Q"F [))0'"0"^0L+

‡1
7m
1
7
Š1
m

|

‡1
79
1
8
Š1
9
Vh
V gyKo"#h‚D?‡'Dy
P")R)+


K|

'tD)R))@"#'j)ghKghK*)'P"
‚g|

6

h‡2g&gfg|

h 6

hhF [)'()*"" U0A
0h -c?"#|

‡?

?

Š?

'>O''"mO'O•"#)R)U^$d"#
DR"K41c?"#fV
•fg|

hVge'M‡?

?

?


Š?

?

h
Oh Ž• 6

VNA$q"Ž" L)R)W5A#u1m`_'(yO'
Ž‡g

Š
m
h
)h ŽŽ•g&

g

h&

g

hŠ&
m
g
m
hhV?D"#F]&

g


hR"W3O

O

ŠO
m
'")R)W5AO')Y0,a"'^'A)"#?K)')Y0)R)OI"#
&

g&
ODW
h'?D"#F]?‡•O

•O
y
K)‡O

O

O

O
7
L1'U\"4,5"'>
'!7Vl"#3"&

ghUx)D?‡K)‡K`M'JAIL7
ONA$q"$ !$3"#"4,5"LV
$h ŽŽŽ•2gŽŽh'?D"#F]2LDR"K4)\F4"FNDR"K4O')Y0
ŽŽ‡'


'

Š'

U"?0'
y
'
9
Š'
7
V
KV O

O

ŠO
y
•g|
y
+
y
hgFkK4'?P)Y0)R)`\)A\)r"#+
y
|
y
KV •2

gO


O

ŠO
y
hgOM"FkU^$d"#2

‡O

O
m
ŠO
7
h
&bFuyKo"#L.,)Y0f&
e"&bFu1G]0f&
2. Hóa vị IP và hoán vị ngược IP
-1
I"#DR"K42F [)F 0?0'?D"#OI"#$ !F5B
7
m
7   y m   y 7  y m   
y 7 y m    y y 7y m    y m
79 8   7 9 8  78 7  7 9 8  
y 7 7 9 8   7 y 77 9 8   7 9
I"#I"#DR"K42


m m y 7y  y  8 9 9 7 77  y 

m

y y  7  y 

9 7 7  7  y 8
y    7  y 
m
7    7 8 78 9
    7 m 7m y    8 8 9 79 7
I"#I"#DR"K4"# [)2

0DR"K42K2

`@"#)]_"#T0#eKZ1.'1Q'1G1D"'D"
"•1'3DFZA`*")DK*)‘),]0’'AQ''DR"f&V
&bFu)XA'?“)1'Ko"#f&
e"&bFu1'Ko"#f&
3. Thuật toán sinh khóa con
- EURAKo"#L.,)Y0f&)3B)r"#'AQ''DR"" "0A" "#K!y
`]0)D"`R)"0AVR)`]0)D"FZAF [)U"?0'>`]0)P")Y0
f&O•"#1''AQ''DR"U"`]0)D"V6]0)P"6gyO'hFJA0y
O !)OM"Fk'31wO !)OM"Fk"B1'`]0)D"F [)U"?0K!
F$mO'V
]'N1@'I'AQ''DR"U")R)`]0)D")'M'" U0A
",A'`]0yO'6‡`

`

Š`
y
gO0D#u1)ImO'`N1'?0'P")ƒ"L„h
A',A'y`]0)D"mO'6


ŒŒyV
V 4""#T0K

ŒŒy" U0AK

‡F\K!”•8y–ˆK

‡
)D)R)'? E"#[,`R)g5BL)R)#R'?4$4)'?R)D)R)Ko"#m
O'OC"$ !hV
V •2g6hˆONA$q"'")R)"^0mO'g



hg&^$d"#OI"#
2FN)S")R)O''>6

‡`
79
`
8
Š`
y


‡`
y
`
77

Š`

Vh
V }D?‚?D1'Dy'P")R)6

" U0A

•g

•K

h

•g

•
K

h6

•2g



hVg&^$d"#2FN)S"mO''>W5A#€,O

O

Š
O

7y
)Y0

K

V6

‡O

O
9
ŠO

V—•ŽL`_*A$4)Ko"#'?RhV&bFu
U")R)`]0)D")Y0f&
e"&bFu'3D`]0)D")Y0f&
yO'FaAKDUx#I1WA\"#)o"7yO'O•"#)R)O‹FmO'gc)R)K4'?P
)0M')Dmh)R)O'"B$r"#FN`N1'?0O')ƒ"L„V&0AF]7yO'"B
L3F [)'?P)LXBmO'FNU"?0)DyKo"#`]0)Y0f&V
I"#'?Q''(`]0g2h
79 8   7 9 8  7m 7   y m
  78 7  7 9 8   y 7  y
y 77 9 8   7 9 y 7 y m  
 y y 7 7 9 8   7 m   
I"#I"#2
aA'C"7yO'`]0F [))0?0'"0"^0mO'V&0AF]0"^0m
O'"BF [)$4)Ko"#'?RD.)D.)O',d'A)KDU\O'$4)
' b"#j"#K!Ko"#F]V
&\O'$4))Y0)R)Ko"#g+&h
o"#L.,

    7 y 9 m 8      7 y
&\O'$4)
               
I"#7I"#$4)O''3)R)Ko"#L.,)Y0f&
&0A`$4)Ko"#1'OI"#)S"mO'F [)U^$d"#Ve)R)DR"K4
"B)Y0)R)O'F [))S"" 1''k[,)D")Y0)R)O'"C"F [)#SL
‘DR"K4"€"’0B‘'?Q''("€"’V
I"#'?Q''("€"g2h
 9    7  m 7 y  
 8   y m y 9 9   
 7  9 9 77   7 7  m
 8 8 7y  7 y  7 y 8 
I"#yI"#2
P$d" )“"#'0)]'N"Q"'XBO'cK4'?P)Y0`]0Ux$4)U0"#
K4'?P7?0"#D)o"O'cK4'?Pm)Y0`]0UxO4O‹JA0VP"K*)
$4)Ko"#"B'3D"C"1''Q,[,)D")Y0`]0F [)U^$d"#'?D"#1w
'k[,`]0$r`@"#,I'X')I)R)O'F [)U^$d"#1')R))P"
WR))r"#1'L“)'?D"#1wLa"U^$d"#V
4. Mô tả hàm f
1‚g|

6

hL1'1)]0OM"KDOM"'j"X'|

L1'W5A
O')]F$O'V1‚)]'NL1OX'`v'AB"C"Ke"#Au"#\)
‘Uj)13"’)Y0f&"•1'?D"#1‚"C"K*))S"1‚,I)…"'Q"
FN'?R"O4,R1G1')R)$q$"#V@"#' E"#1‚F [))S"
' E"#L1)]'P")X'‚‡‚


'j)‚g‚gWhh‡WV
?D"#UbFu1@'I1G]0)Y0f&F [))@"#O\Oc˜BO0"CA)A…"
nA\)#0D06vgt="'t$0'D"A?t0AD‚&'0"$0?$h1‚'()
*")R)K*)U0A
• M"'j"X'|

F [)1c?"#'"1'W5AO')]F$mO'
'tD1'11c?"#)\F4"fV())X'11c?"#fg|

hL
1'DR"K4)]L.,'?D"#F]L.,L3yO')Y0|

•  0m`\

KDmOI"#&

&

Š&
m
gF [)#SL)R),&
DWhV-w,&DWL1'OI"#•y)\F4")])R))''>FM"
7K)R)"#'>FM"V!1wW5AyO'

‡O

O

O


O

O
7
O
y
'0
'P"F [)&

g

h" U0A0O'O

O
y
WR)F4""#?'?D"#,&


O\"O'O

O

O

O
7 
WR)F4")')'?D"#,&

V6F]&


g

hUxWR)
F4",a"'^

‡&

g?)h,a"'^"BKM'$ !$3"#"4,5"O'V
 KQBm`\yO'

gŒŒmhUx)D?0m`\O'

K!
gŒŒmhV
• ~5AO'‡








7

y

9


m
)]F$O'F [)DR"K4'tD
,€,DR"K42g,2DWhV6M'JAI2ghUxL`M'JAI)Y01
‚g|

6

hK)p"#)P"L|

)DKo"#U0AV
1‚)p"#)]'N1@'IO•"#e"KxU0A
e"7&bFu1‚
5. Hàm (ánh xạ) mở rộng (E)
11c?"#™Ux'/"#F$)Y0|

'>O'LC"mO'O•"#)R)'0B
Fk)R)'j'()Y0)R)O')p"#" L.,L3)R)O'V*)'()*""B
"•101d)FP)
• +1F$)Y0|

 )r"#)šK!`]06FN'()*"K*))"#
1D$ALD~|V
• D`M'JAI$b"FN)]'NF [)"€"'?D"#UA\'JAR'?e"'0B
'MV
AB"C")I01d)FP)"BFZA"•11'1d)'CA)P"LOID1Q'
$iL*AV•"#)R))D,€,O')]'N)›"KD0K4'?P'0B'MU(
,d'A))Y0)R)O'FaA?0K!)R)O'FaAKDUx'?I?"#?0Vf&F [)
'M'`MK!FZA`*"L1wO')Y0OI"1G,d'A)KD1wO')IAOI"
?sK`]0V
&bFu11c?"#

e"y&bFu11c?"#gfh
@`"]F [)#SL1fDW1wO')Y0`\KDO''j"X'K
O''j' ' b"#j"#K!O')Y0FaA?0'?D"#`O''jKO''j
' b"#j"#K!O'cFaA?0VI"#U0AF5B1CA'IK4'?P)Y0O'?0UDK!
O'KDV
I"#1@'I11c?"#gfh
     7  7 y 9 m 8
m 8        7 y 9
y 9 m 8        7
 7 y 9 m 8 m 8    
I"#9I"#1@'I11c?"#f
P$d" O'cK4'?PU\)Y0`\KDUx$)ABN"FM"K4'?PU\)Y0
`\?0KO'cK4'?PcFaAKDUx$)ABN"FM"K4'?PKcFaA
?0V
6. Mô tả hộp S-box
7. Hộp P-box
III. Ví dụ về mã hóa khối DES
IV. Hạn chế của mã hóa khối DES
1. Tính bù
2. Khóa yếu
3. DES có cấu trúc đại số
4. Không gian khóa k