DES, , Rijnael

DES, , Rijndael.

1. . 2 n , 64, 256 ..

2. . .

3. .

.

:

, F F, .

f(f(x))=x. . DES .

I. DES (Data Encryption Standart)

64 .

56 .

.

16 .

: -> ->16 -> ->.

64 , .

.

: 16 56 48 . 56 2 28- . 1 2 . , 56-48 ( ).

32 48 ( )

: - 2 . E (expansion).

XOR . ( S box). 8 S box 6 , 4 . DES, . P .

. 40 .

- , , . 64 , .

Des DES .

II. ( )

64

256

32

8 S ; ( ) 2^32. S box 0 15. : 256 8 32 . .

S .

S box ; , DES .

II. Rijndael (AES, Advanced Encryption Standart).

AES (Advanced Encryption Standart) . NIST ( ) . (Rijnael). , : Vincent Rijmen Joan Daemen.

Rijnael :

1)

2)

3)

II. .

Rijnael . 128, 192 256 . , , , 128 128 10 .

( 4).

DES, Rijnael . . , , 4 . 128 128 . , ( ).

: (State)- . . : , ,,,,,,.

. 4- , . . , , :

Round{

ByteSub()

ShiftRow()

MixColomn()

AddRoundKey()

} MixColomn().

ByteSub ( )

ShiftRow ( )

MixColomn ( )

:

1. , . :

1) ( GF(256), 0 ).

2) :

, : , GF(256).

2. :

. , 1 , 2 ( ).

mNop

Mnop

jKl

j

dEf

de

wXyz

wxy

.

3. :

GF(256) , . , .

: ,

:

.

4. .

2 .

=

.

.

: , .

, , 1, 128 10 1408 . 128 .

: ( 0-3) , :

,

5-7 : . , . SubByte , RotByte- , (a,b,c,d) (b,c,d,a).

:

N-1

.

III. .

:

{

}

. . , , . :

AddRoundKey();

InvShiftRow();

InvByteSub();

AddRoundKey();

InvMixColumn();

InvShiftRow();

InvByteSub();

AddRoundKey(); , , .. . ,

AddRoundKey();

InvMixColumn();

InvMixColumn()

AddRoundKey(InvRoundKey); InvRoundKey

InvMixColumn() . . :

AddRoundKey();

InvByteSub();

InvShiftRow();

InvMixColumn();

AddRoundKey(Inv);

InvByteSub();

InvShiftRow();

AddRoundKey();

, . . , .

IV. .

. , - EXOR, S-box, . 32 . , S(a), 4 , S(a) ( 4 ), XOR . , , , , .

( P-200)

(, )Ansi C, Mbit/secVisualC++, Mbit/sec

(128,128)27.070.5

(192,128)22.859.3

(256,128)19.851.2

V. .

, .

1. .

1. , , {0,1} : .

0x57 (01010111) : .

2. . , , 2 . , EXOR (). , .

3. .

: , .

8. , .

, 0x01. , 256 .

3.1 .

:

EMBED Equation.3 , ,

,

EMBED Equation.3 , x XOR c 0x1b.

4. .

. 4- 4. . 2.4.1. .

, .

,

, , .

.

1. 16 2 GF(256).

2. .

3. .

4. ,

5. GF(256),

6. .VI. : ECB, CBC, CFB, OFB.

1. ECB (Electronic Code Book). .

2. CBC (Cipher Block Chaining).

3. CFB (Cipher FeedBack).

4. OFB (Output FeedBack).

Li

(

Ri

F

Li+1

Ri+1

S-box

No shift

Cyclic shift by 1

Cyclic shift by 2

Cyclic shift by 3

EMBED Equation.3

Ki

Symmetric ciphersPage 1014.03.2003

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