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Title: E-mail: hjbin@infosec.pku.edu.cn

1
?????(2)

???
??????????????
E-mail hjbin_at_infosec.pku.edu.cn
http//infosec.pku.edu.cn/hjbin

? ?
??????
??????

3
??????(Data Encryption Standard,DES)
4
??

?????IBM?? W. Tuchman ? C. Meyer
1971-1972?????
??1967???Horst Feistel?????
?????????(NBS)1973?5??1974?8???????,
?????????????????????????????
?IBM?LUCIFER??
???DES??1975?3?????,1977?1?15???????
???????????(Data Encryption
Standard),?
1977?7?15???

5
??

???????(NSA, National Security Agency)????????????
??????????NBS???NSA?????,???????,???????LUCIFER???
?128????56?
1979?,??????????DES
1980?,DES?????????(ANSI)??
1984?2?,ISO????????????(SC20)?DES????????????????

6
DES??

????????????64?????
?????????????????,??????
????56?,????8???????,???
???????56??,??????,????
??????????,??????????,?16?
??????????????,????

7
DES?????????
8
DES????
9
DES????
?i??????,??????2??,f?????
10
DES????
?i??????,??????2??,f?????
11
DES????????????
12
????IP??????IP1
13
IP?IP1
IP
IP1
14
DES? ????
15
????E-?-32????48?
??
16
????S-?-48????32?
?8?S?
17
S-?1
S-?5
S-?6
S-?2
S-?3
S-?7
S-?4
S-?8
18
S-????
19
S-????

DES??????????,?S-?????????
S-??????,??????????
??S-?????????

20
S-??????

S????????0,,15?????
????S????????????
??S???????????????????
?????S????????X,S(X)? S(X?001100)?????????(??X???
?6????)
?????S?,????????e,f??0,1,S(X) S(X?11ef00)
?????S?,??????????,????????????,???????0?????????
???????1?????

21
S-??????

S-????????????????,??,??????????????????
???????????????
?????????S-????????????S-???????????????
??????????????????????????

22
??p-????
23
p-??????

P????????????
??????????????????????

24
DES????????
25
???????????

?????????????????
????
??
???????( ??????????????,??????????????)
????????????????????????
?????????????????????????
?????

26
DES? ????
27
DES?????????
28
DES?????
29

????? ECB (electronic codebook mode)
?????? CBC (cipher block chaining)
???? CFB (cipher feedback)
???? OFB (output feedback)

30
?????ECB
31
ECB???

?????
??????
???????????
??????????,????????????
????????????
????????????????
??????????????????
????????

32
??????CBC
33
CBC???

???????????
??????????
??????????IV
??????????
?????IV?????????
?????????????
??????????????????
????????????????
?????ECB
?????????64????,?????????,????????? SSL?IPSec

34
????CFB

CFB????????
??Si ??????,?????jbit
?? Ci Pi?(EK(Si)??j?)
Si1(Siltltj)Ci
?? PiCi?(EK(Si)??j?)
Si1(Siltltj)Ci

35
Ci Pi?(EK(Si)??j?) Si1(Siltltj)Ci
????CFB??
36
PiCi?(EK(Si)??j?) Si1(Siltltj)Ci
????CFB??
37
CFB???

????????
???????????
???????
?????????????IV
???????,IV????
????????????????

38
????OFB

OFB????????
??Si ??????,?????jbit
?? Ci Pi?(EK(Si)??j?)
Si1(Siltltj)(EK(Si)??j?)
?? PiCi?(EK(Si)??j?)
Si1(Siltltj)(EK(Si)??j?)

39
Ci Pi?(EK(Si)??j?)Si1(Siltltj)(EK(Si)??j?)
????OFB??
40
PiCi?(EK(Si)??j?) Si1(Siltltj)(EK(Si)??j?)
????OFB??
41
0FB???

????????
???????????
???????
?????????????IV
???????,IV????
?????????????????
????????????
????????????????
????CFB?

42
??DES
43
??DES
44
??DES
45
DES????
46

F??(S-Box)??????
???????
DES???
????????

47
DES????

??DES???????????????????56?????????????????,??????
? ?
??1977?,Diffie?Hellman????????????100?????VLSI????
???100????????????????????????????????????????2000
???

48
DES????

?CRYPTO93?,Session?Wiener?????????????????????,??
???????????????,??16???????????10???,???1.5???????
DES??
???????????Verser?1997?2?18??,??96???,?Internet???
??????????,??????DES???,??????1???

49
DES????

1998?7????????(EFF)????25???????56??????56?????DES
1999?1?RSA????????,????????22??15??????????DES???

50
??DES

1990?,???????Eli Biham?Adi Shamir??????????,??DES?
???????
????????????????

51
????????

??? EK?EK I ,DES??4????
?
???? EK1 EK2 ,???12?????
?

52
??????????
53

Triple DES
IDEA
RC5
RC6
AES
??????????,?Blowfish,CAST,??RC2?

54
????????????
55
???????
???? ???
???
56
??????????
57
?????????????
58
???????????
59
?????

??????????????????,???????????????????
??????????????,?????????????????,?????????????????
???,?????

60
????????

?????????????????????????,??,?????????????????????
???????,???????????????????
??????????????????????????????????,???????????????
??,???????????????

61
????????

????????????????????,???????????????????,?????????
?????????????????????????????????
???????,????????????????,?????????,???????????????
?,??????????
?????????,?????????????????????,??????????,???????
??????,???????????????????,???????????????????????
???,??????????????????????????????????????????????
?,???????????????

62
????

????????????????????????????????????????????????
???,??????????????????????,?????????????
??,???????,?????????????????????,????????????,????
????????????,???????????????????
????????????????????,?????????????????????????????
?????????????

63
?????

???????????????????????????????
???????(??????????),??????????????????,???????????
??????,??????????????????

64
????????

?????????????,???????????????,???????????
??????????????????????,???????????????,???????????
??????????????
?????????????,?????????????????????????,??????????
???,??????????????????

65
????????

?????????????????,??????????????????????????????
???????????????????????,????????????????????

? ?
??????
??????

67
??????

????????????,??????????,????????
???????????,????????
???????,????????????????????????20?????,?????????
??,????????????????????????

68
?????????

??????1976??Diffie?Hellman??????????????,???
W.Diffie and M.E.Hellman,
New Directrions in Cryptography,
IEEE Transaction on Information Theory,
V.IT-22.No.6, Nov 1976, PP.644-654

69
?????????

RSA??????Rivest,Shamir?Adleman?1978?????
??Communitions of the ACM. Vol.21.No.2. Feb.
1978, PP.120-126
???????????????Euler(??)??,???????????????

70
???????????

?????????????
??
??
??????,????????????????????
????????????????????????(?????)

71
???????????
72
?????????

??????????(KU,KR)
?? KU??,??KR??

73
???????????
74
?????????

???????????????????????????
??
????

75
??????

?????????,??????????
????????(IFP)?????
????????(DLP)????
????????????(ECDLP)?????

76
Diffie-Hellman??????
77
????????

?????????f
(1) ??x,??yf(x)????
(2) ??y, ??x?yf(x)????
(3) ??z,??z ?, ??????y,????x?
?,???x?yf(x)????
????x f-1(Y)???????????,??????

78
????????

???(1)?(2)??????????(3)??????,z ??????
??????f???????,??f??,??????????,????????????,??Pk
f???????z??,??????,??z??????,??Sk????????Sk,??????
?xf-1(y)
????????(2)??????????????yf(x)??x?????

79
Diffie-Hellman??????

Diffie?Hellman???????????,??????????,?????????????
?????,??????????????????
??,???????????,???????Diffie-Hellman??????

80
Diffie-Hellman?????????

?????????????????????F????,g?F?F????
FF\0ltggt,????????x,??gx????????g?y?x?y
gx,??????????
?????????F???????????????????????????FP

81
Diffie-Hellman????????

Alice?Bob????????p,?????g,1ltgltp,g???FP?????,?FPlt
ggt
p?g????,????????????

82
Diffie-Hellman????????

?Alice?Bob????????,???????????
(1) Alice???????x,??? X gx(mod P)
(2) Bob???????x?,??? X ? gx ?(mod P)
(3) Alice?X???BobBob?X ????Alice
(4) Alice??K (X ?)X(mod P) Bob??K ? (X)
X ?(mod P),
??,K K ? g xx ?(mod P)
?(4)?,Alice?Bob??????????K
???K?????????????????????

83
RSA ??
84
Euler ??

???m?r??????????r
???r???????m????????r?m??
?m?????????f(m)??,?m?Euler??
?m????,??m???????m??,??f(m)m-1
?npq, p?q ???,f(n)f(p)f(q)(p-1)(q-1)

85
Euler ????
?p3, q5, ?? f(15)(3-1)(5-1)8
?8??15????? 1,2,4,7,8,11,13,14
86
RSA?????

???????Bob????
(1) Bob????????p?q
(2) Bob???npq ?f(n)(p-1)(q-1)
(3) Bob???????e (0ltelt f(n)),??(e,f(n))1
(4) Bob?????????de-1(modf(n))
(5) Bob??????n?e????
???????RSA????????????n???
????npq,?????f(n)(p-1)(q-1),????
??e,?????d

87
RSA????

??TN
??SKD
??PKE
???M,??C,??
?????ME mod N C
?????MD mod N M

88
RSA????

? p7, q17, n717119 ??Tn119
f(n)(7-1)(17-1)96
??e5, gcd(5,96)1 ??pk5
??d, ( de) mod 961 d77 ??sk77
???m19
??(19)5 mod 119 66
??(66)77 mod 119 19

89
RSA????????

???????RSA????????????n
??????npq,?????f(n)(p-1)(q-1),??????e,?????d
??RSA??,p?q????????,????????????????n????

90
RSA????????

????p?q???100???????
?n????????512??
EDI???????RSA?????n????512?1024?????,????128???
????????ISO/IEC 9796???n????512???

91
RSA????????
?????????????,?RSA?n????p?q??????
(1) p-q??,?? p?q????? (2) p-1
?q-1????????p1?q1 (3) P1-1?q1-1????????p2
?q2 (4) p1?q1????????p3?q3
92
RSA????????