wbuzova_umk_met_i_sred_zash_kom_infor_2012
.pdf
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3.3 - 32LFSR
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: 4[245-262]
: 14[182-200]
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1.?
2.?
3.?
4.?
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6.-
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7.-
?
4. .
DES. .
-
= ) = DK( ), |
(4.1) |
- ( ) ; - .
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, ,
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, 4.1.
4.1
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X’ = + V |
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X’ = X XOR V |
(2N + 1) |
X’ = (X* V) mod (2N+ 1) |
2N |
X’ = (X* V) mod (2N) |
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X = XSHL V |
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X = XSHR V |
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X = X ROL V |
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X = XROR V |
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S-box (substitute) |
X’ = Table [X, V] |
V -
.
-( , X’ = X + 125);
-, ( , X’ = X + F( ));
-, ( , 2’ = 2 +
F( 1)).
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DES (Data Encryption Standard) -
DES
.
DES 6464-
, 56 ( 8 - -
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DES 4.1.
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64-
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4.1 - DES
DES -
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1 2 ( 4.2). :
= K1(D 2 1 ))), |
(4.2) |
K1,
2 K1.
EDE (encrypt-decrypt-encrypt).
DK2
DES. :
= D 1 K2(D 1 ))), |
(4.3) |
1
2 K1.
n- , -
2n- .
. -
|
|
= EK3(DK2(EK1(P))), |
(4.4) |
= DK1(EK2(DK3 ))). |
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4.2 - -
28147-89. -
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, 28147-89, 64-
256- .
, , 64- .
N1 N2 32 ( 4.3).
N1 , -
N2, -. ( ): 16
32 .
.
- . N1 -
232 32- .
32- : 0, 1, 2, 3, 4,5, 6, 7. -
.
4.3 - 28147-89
24
- . N1
8 4 ,
.
11
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. S-box (Substitution box) -
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S-box (S- -) S1 …. S8 64 . S 32-
4- -
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32- . ( -
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, 28147-89, -
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: 1[127-146], 3[138 - 162], 4[245-262]
: 13 [138-158]
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1.?
2.-
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3.DES?
4.?
5.,
28147-89?
6.-
28147-89?
7.,
28147-89?
5. .
ES. IDEA.
AES (Advanced Encryption Standard). -
AES, DES, ,
-
.
1997 NIST (National Institute of Standards & Technology) -
25
, AES (Advanced Encryption Standard).
. 15 , -
(RSA Security, Counterpane . .), .
- AES - -
:
-;
-;
-128
: 128, 192 256 .
:
-, ( -
), ( );
-32- ;
-,
-
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. -
2000 .: Rijndael,
, (Vincent Rijmen)
(Joan Daemen).
AES (Rijndael)
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28147-89.
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, AES -
4x4,4x6 4x8 -
( -
). -
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AES ( 10 14
-) -
:
-BS (ByteSub) - ( 5.1);
-SR (ShiftRow) - ( 5.2)
-(MixColumn) - ( -
5.3),
);
-A (AddRoundKey) - ( 5.4).
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state,
«state». AddRoundKey -
Round Key.
5.1 - BS ( )
State
5.2 - SR
State
5.3 - -
State
( ) -
( 5.5).
:
, {BS, SR, , } ( R - 1 ), BS, SR, .
R AES (10,12
14 ) (
).
:
1.BS , -
, .
27
2.SR - ,
.
3.-
d(x), ) * d(x) = 1.
4.,
XOR.
5.4 - (AddRoundKey)
X0R State
5.5 - AES
Rijndael AES -
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:
, . , -
, -
, .
AES
. , ,
, , a AES, , -
,
.
IDEA. IDEA,
(Xuejia Lai) (James Massey), 1990 .
PES (Proposed Encryption Standard, -
), IPES (Improved Proposed Encryption Standard,
). 1992 IPES
IDEA (International Data Encryption Algorithm, -
).
IDEA -
,
, . IDEA
, 64- -
28
. – 128 . -
.
IDEA , . , -
, « -
». ,
, :
-XOR
-2 16
-2 16 + 1. (
S- IDEA.)
16- .
16- .
IDEA 64- , 16-
: X1 , X 2 , X 3 X 4 . -
. .
XOR,
16- . -
. -
.
:
(1)X 1 .
(2)X 2 .
(3)X 3 .
(4)X 4 .
(5)XOR (1) (3).
(6)XOR (2) (4).
(7)(5) .
(8)(6) (7).
(9)(8) .
(10)(7) (9).
(11)XOR (1) (9).
(12)XOR (3) (9).
(13)XOR (1) (10).
(14)XOR (4) (10).
- (11), (12), (13) (14). ( -
), .
:
(1)X 1 .
(2)X 2 .
(3)X 3 .
(4)X 4 .
, .
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. 52
-
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- ). 25
. 2, -
- 3. 25
, .
,
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-
, . ( IDEA , -
, 2 16 = -1 -2 16 + 1, , 0 -
0.) , -
.
: 1[127-146], 3[138 - 162], 4[245-262]
: 14[77-128]
:
1.AES?
2.AES?
3., -
AES?
4.IDEA?
5.IDEA?
IDEA?
6. -
.
-
.
, , .
, . .
b, b = • -
. / b, , b ,
b.
b , : b .
p , p > 1 -
, 1 p. N -
, N > 1 , , ,
1 N.
. N, 1,
|
|
N=p1 * p2 * p * p4 * ••• * pn, n > 1, |
(6.1) |
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