RSA
RSA , ( ). RSA 1977 : Rivest, Shamir Adleman.
RSA : p q n = p*q; n .
e, :
1< e < (p-1)*(q-1)
1 ( ) (p-1)*(q-1).
d , (e*d - 1)
(p-1)*(q 1).
e (public)
d (private) .
(n; e) (public)
(n; d) (private) .
() p q (private) .
(), , n () p q, (private) d. RSA n ( n) .
, M. , M e n: C = M**e* (mod n), e n (public) .
( ) . , C d n:
M = c**d*(mod n); e d , M . d, .
RSA 1024 , 2048 .
RSA DES RSA .
RSA . , (private) , () . .
DES
DES (Data Encryption Standart) , .. , . IBM 1977
DES 64 16 , 56 . DES, Electronic Code Book (ECB) Cipher Block Chaining (CBC).
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56 - 8 ASCII , .. 8 . , 2^56.
DES:
(L') (R') . , L'' R' , R'' L' R' XOR. , . , , . , .
Rijndael (AES, Advanced Encryption Standard)
. , . 44, 46 48 . , , .
. 8- 32- . , 4 .
( 10 14 ), :
ByteSub 88 ,
ShiftRow ,
MixColumn , ,
AddRoundKey XOR.
, .
. , , , . . , , , , . , . .
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:
() =
D() =
. . , . , , . , . 64 .
: DES, AES, IDEA, CAST, SAFER, 3-WAY, CRAB, RC5, Blowfish, GOST .