??? b90901041 ???

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?????

• ??? b90901041 ???

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OUTLINE

• ?????,?????
• ?????????
• ?????????????????
• ???????
• ?????? (SSL??)
• ??

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????? ?
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• ???(Cryptography)

!_at_???
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• ???(Cryptanalysis)

FK YOU
FK YOU
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??????

• ????
• ???????????
• ????
• ??????
• ?????????
• ????,??????????????,???????????

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?????????

• ??? (Secret of Privacy)
• ??? (Authenticity)
• ??? (Integrity)
• ????? (Nonrepudiation)

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???????

• ??

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??(M)--???? ??????????? ??(C)??????
'C E(M)' ???
M
C
???'M D(C)'
M D(E(M))
E???????? D????????
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???????

• ?? (?????)
• y x 3 ? x y 3
• y ex ? x ln y
• ??? (?????)
• y anxn an-1x(n-1) a0 ? x ?
• 1.051103774764883380737596422798e1000
• 1.0763302653592405818752987369452e1003 bla
  (???????)
• ? bla which two primes product ?

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??? VS ????????

• ??? (????)
• DES?IDEA?RC2 ?RC4
• ???? (????)
• RSA?DSA?Diffie-Hallman

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???????

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

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????????(???)

• ?? (Transposition)
• ex strike out while the iron is hot
• ????
• tohsinoriehtelihwtuoekirts
• ????
• srkothlternsotieuwiehioiht

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????????(Cont)

• ??
• ??? Principles of CMOS VLSI
• ???csOisMenilCLVfprPioS

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????????(Cont)

• ?? (Substitution)
• Shift right 3
• bohn is strong ? erkq lv vwurqj
• Using Key (p3.1415 )
• 314153141531..
• bohn is strong ? eplo nv txstqh

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DES

• ??????????????DES(Data Encryption
  Standard)?1977????????????????????????DES,????????
  ,????????????????????DES??????????????????????????
  ???????,??????????????????????????????,??20?????,?
  ???DES??????,?DES??????????,????????????DES,?DES??
  ????????

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????? (???)

• ??
• ??????
• ???????
• ???????
• ??
• ??????
• ???????
• ?????????

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????????

• ????????,???????????????????? (public key) ??????
  (private key),??????? (???) ????,??private key
  ??????,public key ?????????????public key
  ??,??????? private key ???

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??? ????,???? ??? ???? (??),????(??)
B Private key
B Public key
A Public key
A Private key
B
A
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RSA

• ???? ????????
• ????????? p?q,?????pq?????? e,?? e ?
  (p-1)(q-1)??,???? d,?? (ed-1) ? (p-1)(q-1)???????
  (n,e) ?????,(n,d) ??????

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???????
B Public key
A Private key
A
B Private key
A Public key
B
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?????????????

• A ?????? B
• ????
• A ???? private key ??,? B ?? A ? public key
  ??,????? A ???
• ????
• A ? B ? public key ??,B ???? private key
  ??(??)?

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????? (???)

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

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???????? SSL
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• SSL(Secure Socket Layer)?Netscape???????????,???RC
  4?MD5,??RSA??????????????????SSL??,?????????????,?
  ?????????????????SSL?????,?????????,??????????????
  ?????
• ?SSL?????????????????????,?????????(key-length)??,
  ?????!???????????,??????????128-bit,???????40-bit
  ?40-bit?key???????????????????

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SSL (Cont)

• ??SSL ?????,???????????(session
  key),??????????????,??????????????????????????????
  ???????????????????????????,SSL
  ??????????????,???????????(publickey)????????????,
  ??????????????????(private key)?????????????

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??

• ???????,?????,????????? (trade off)
• ??? ? ????????????,?????????
• ???????????? (???????),???????? (1016 ? )
• ??????? (????????)
• (????????)

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THANKS FOR YOUR ATTENDANCE