, , , , - , . .
, . , , (whitening), , , .
, . , .
, . , 128 , 64 . , .
, 95 , , Fi (Ri, ) .
2.6
, , , , . , . , .
, ( ).³ , , .
, , . . . , , , .
, .
2.7
2.7.1 .
, , , .
ϳ . , .
|
|
, 2.
, , 64 . .
г
, i = 1... ,
i - ; i - ; i - ; .
. г
= .
, . , . , . .
2.7.2 .
, , ( = 00000, = 00001, = 00010 . .), 2 .
. .
, ( γ , ).
' , , , , .
( ) ' :
;
, , ;
.
. . . , . .
' : , ? . , , , , .
|
|
䳿.
1946 . , . .
. Y 1, Y 2,..., Y -1, Y,...,
Yi = (a Yi -1 + b) mod m,
Yi i -e () ; Yi -1 -; , b m ; m ; (); b . Yi Yi -1 , b m. , , b m m. m 2 n ,
m = 231 1. b m, .
, , , , , . ֳ 224 . . , , , , .
.
:
;
(2.7.1)
,
h 0 0, hk = 1 hi GF (q).
0, 1, 2 ,... GF (q). (2.7.1) ak 0, 1, 2 ,..., k 1. 0, 1, 2 ,..., k ak +1 . . 0, 1, 2 ,..., k 1 , k . '; , hi ai 0 1 GF (2).
.2.13 , (2.7.1) , , ak k . 0, 1, 2,..., k 1 , ; i - ai. , '.
:
2
() h, h = 0 1
' , ,
= 0 = 1
2.13
, , .
|
|
h (X) = hj j ,
; hj j , 0 1; h 0 ≠ 0, hk = 1, n , Xn 1 h (X). ,
g (X) = (Xn 1) / h (X).
hj ai+J = 0
a 0, a 1, ai, , an 1 , , (Xn 1),
a (X) = a 0 Xn 1 + a 1 Xn 2 + + an 2 X + an 1,
, g (X) (Xn 1).
, a (X) 0, 1, 2, , a (X) , . ,
' () hj . , h (X) hj = 1, , hj , h (X) hj = 0, hj . h (X) . h (X) m 2 m 1.
' (.2.14),
h (X) = X 3 + X 2 + 1,
h 3 = 1, h 2 = 1, h 1 = 0, h 0 = 1.
2.14 '
101. ; .2.14. 101. '. (Maxmal Length Shft Regster Sequence MLSRS). - m m - MLSRS 2 m 1. m = 100 2100 1 1016 ' 1 /.
( ) ' 1010011, . , , 7. , 10 01 ' , 00 11 , , . m - , . . , m - . , .
, ' .
|
|
' , m . m , m 2 m . m ' . , , .
' , , 2 m , .
S () -, m 0 1 - .
S (i + 1) = A S (i) mod 2,
m ´ m, '.
(.2.14)
= .
: , , .
2 m 2 m . , 2 m . ,
S (1) m ;
S (2) ( 2) m
;
S (m + 1) m .
m ´ m:
X (1) = [ S (1), S (2), , S (m)];
X (2) = [ S (2), S (3), , S (m + 1)],
'
X (2) = A X (1) mod 2.
, - X (1) ,
A = X (2) [ X (1)]1 mod 2.
(1) () m 3 , - m.
MLSRS , . , "" , ', .2.15.
2.15 ˳
f , , , . , . (2 m 1) ( : m = 3 23 1 = 7), (2 m 1) ( h (X) m). m , , : 2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281, .
, m - ', '. (2 m 1) , .
3
3.1
, ' , . , , . .
. , , . , .
г .
|
|
, . , .
-
, . ( ) . ( ) . -, . , ( ) , .
- .
( -, ). ' . . . , .
. , .
. . , .
, , , , .
, (). , , , . , , .
, , .
3.2 ճ
ճ ,
,b: → → ;
,b: t → ,(t);
,b (t) = at + b (mod m),
a, b , 0 £ a, b < m; ( ) (a, m) = 1, n -
, , m, . ʳ , , .
, ,
: → .
, ճ, .
∑, ∑ . :
3.1 - ³
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |