IDEA (International Data Encryption Algorithm) . 64- . IDEA , 128 . , .
IDEA 1990 ., - . .. PES (Proposed Encryption Standard). , 1991 ., IPES (Improved Proposed Encryption Standard). 1992 . IPES IDEA. IDEA , .
IDEA :
- 2 ( " "); (+);
- 216; [+];
- (216+1), 16 216; ().
16- .
, :
- ,
a[+](b(+)c)#(a[+]b)(+)c; - ,
a[+](b()c)#(a[+]b)()(a[+]).
, - IDEA DES, " ".
IDEA .1. 64- 16- . . . . :
1. () - X1 .
2. [+] - X2 .
3. [+] - X3 .
4. () - X4 .
5. (+) - 1 3.
6. (+) - 2 4.
7. () - 5 .
8. [+] - 6 7.
9. () - 8 .
10. [+] - 7 9.
11. (+) - 1 9.
12. (+) - 3 9.
13. (+) - 2 10.
14. (+) - 4 10.
.1. C IDEA ( )
, 11, 12, 13 14. ( ). .
|
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:
1. () - X1 .
2. [+] - X2 .
3. [+] - X3 .
4. () - X4 .
Y1...Y4 .
Z1...Z6 . 52 ( ). 128- 16- . - ( - - ). 128- 25 ( - - ). 25 .., .
, , , (-x), (1/x) (.1).
1 IDEA | ||||||||||||||||||||||||||||||
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IDEA , (1/x) 0 0.
IDEA DES. DES, 128- IDEA DES. IDEA . DES. IDEA .