http://www.icst.pku.edu.cn/InfoSecCourse

1
??????????? (?)

• ???,??????????
• http//www.icst.pku.edu.cn/InfoSecCourse

2
??

• IPSec
• ??
• ????
• PKI

3
IATF(????????)???
Enclave Boundaries
Networks Infrastructures
Classified Enclave
Telecommunications Service
Local
Providers (TSPs)
Computing
Environment
Remote
Users
Private Enclave
Local
Computing
Remote
Environment
Users
Connections to Other Enclaves
Public Enclave
Internet Service Provider
Remote
Local
Users
Computing
Remote
Remote
Connections
Environment
Users
Public Telephone
Via TSPs
Network
Remote
Users
PBX
Facility
Enclave Boundaries
Supporting Infrastructures
Boundary Protection
(Guard, Firewall, etc.)
1 Detect Respond
Remote Access Protection
2 Key Management Infrastructure/Public Key
Infrastructure
(Communications Servers, Encryption, etc.)
4
IPSec

• ??????
• ?????(??)????????
• ???????????????,???????????????????????
• ??IPv4????????????????
• IPSec?IETF???????IP???
• ??IP?????IP????????
• IPv4???????????,?IPv6???????????
• ??????IPv4???

5
IPSec???

• ????,??
• AH Authentication Header
• ESP Encapsulating Security Payload
• ????(Key Management)
• SA(Security Association)
• ISAKMP?????????
• IKE?????????IPSec???????

6
SA(Security Association)

• ????
• ??????????IPSec????????????????,??????????????????
  ????????????
• ??SA??????,??,????????,?????SA
• SA?IPSec?????????????
• ???????(SPD)
• ???????(SAD)
• ??SA?????????
• SPI(Security Parameters Index)
• ????IP
• ??????

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SPD SAD

• SPD
• ??????????
• ????discard, bypass IPsec, apply Ipsec
• ????
• ?????????,?????IP??
• SAD,?????????
• Sequence Number Counter
• Sequence Counter Overflow
• Anti-Replay Window
• AH Authentication algorithm, keys, etc
• ESP Encryption algorithm, keys, IV mode, IV, etc
• ESP authentication algorithm, keys, etc
• Lifetime of this Security Association
• IPsec protocol mode
• Path MTU

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AH(Authentication Header)

• ?IP?????????????
• ??MAC?????,??????????
• ?????SA??
• ????????
• ??????
• ???????IP??,????AH
• ??????????IP?,?AH??????IP????IP???????

9
AH???????
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IPSec Authentication Header

• Next Header ???????
• Payload LengthAH???(32?????)
• SPI????SA
• Sequence Number????????
• Authentication Data??????,????????ICV??MAC

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AH????

• AH??
• ?IP???,?????????
• ????
• ??ICV??MAC
• ???????(Outbound Packet )???,??AH
• ??SA
• ?????
• ??ICV(Integrity Check Value)
• ????IP??????AH?????????
• ??

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AH????(?)

• ???????(Inbound Packet )???
• ????
• ??SA
• ????IP???AH???SPI
• ?????(??,??????)
• ?????????????????
• ICV??

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ESP(Encapsulating Security Payload)

• ??????,?????????
• ???????????????????????IP??,ESP???ESP??????
• ??????????SA??
• ???????????????

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ESP???????
??????
??????
Orig IP Hdr ESP hdr TCP Data ESP trlr ESP auth
(1) ????
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IPSec ESP??
0 8 16
24 32
Security Parameters Index (SPI)
Sequence Number
????
????
Payload Data (variable)
Padding (0-255 bytes)
Pad Length Next Header
Authentication Data (variable)
16
ESP????

• ESP???
• ??????????SA??
• ???????(Outbound Packet )???
• ??SA
• ??
• ???????,??payload data???????,?????????
• ?????padding??
• ????
• ?????
• ??ICV,??,????????????
• ??

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ESP????(?)

• ???????(Inbound Packet )???
• ????
• ??SA
• ????IP???ESP???SPI
• ?????(??,??????)
• ?????????????????
• ICV??
• ??
• ??SA????????????,??????????????
• ??padding
• ?????IP?

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AH?ESP?????
Transport
Tunnel -----------------
---------------------
1. IP1AHupper
4. IP2AHIP1upper 2.
IP1ESPupper 5.
IP2ESPIP1upper 3.
IP1AHESPupper

• ??upper???????
• IP1????IP?
• IP2??????IP?

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IPSec??

• ????
• ?IP???????
• ????IP???????
• ????????,????????
• (BITS) Bump-in-the-stack
• ??IP????????????
• ?????????
• BITW (Bump-in-the-wire)
• ??????????,???BITS??
• ????BITW??,????IP???

20
IPSec????

• ISAKMP Internet Security Association and Key
  Management Protocol
• RFC 2408
• ???????????????
• IKE The Internet Key Exchange
• ??ISAKMP??
• ???Oakley?SKEME?????????

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ISAKMP

• ?????
• ??SA
• ????,????
• ????????????
• ????
• ????????????????
• ??????????
• ??????????payload??
• ??????????????

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ISAKMP????

• ISAKMP????

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??payload
Type Parameters
Security Association(SA) DOI, Situation
Proposal(P) Proposal , Protocol-ID,
Transform(T) Transform , SA Attributes
Key Exchange(KE) Key Exchange Data
Identification(ID) ID type, ID date
Certificate(CERT) Cert Encoding, Certificate data
Certificate Request(CR) Cert types,Cert auths,
Hash(HASH) Hash Data
Signature(SIG) Signature Data
Nonce(NONCE) Nonce Data
Notification(N) DOI, Protocol-ID,
Delete(D) DOI, Protocol-ID,
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?????(Two phases of negotiation)

• The first phase, ???ISAKMP SA
• ??(??ISAKMP Servers)???????????
• ?SA????????protocol SA?????
• The second phase, ????????????SA(??,IPSec SA)
• ??????????SA
• ?SA??????????????????????

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????????

• ???????,???????????????
• ??,????????
• ?????????????????????,?????SA??????ISAKMP SA???
• ????????????????????????
• ??,?????ISAKMP SA??????????????????????,??????????
  ?????
• ?????,????????

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?? Diffie-Hellman????

• ???????????????????,?????????
• ??????????????????
• ??
• ??????q??q?????r
• A??Xltq,??XArXmod p, A?B XA
• B??Yltq,??YBrYmod p, B?A YB
• A?? (YB)X?(rY)X?rXYmod p
• B?? (XA)Y?(rX)Y?rXYmod p
• ??????????(rXYmod p)
• ??q??q???r?????

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Cookie exchange

• ?? Diffie-Hellman???????????
• ??????????
• Clogging attack
• Cookie exchange
• ???????????????????,?cookie,?????????????
• Cookie???
• Cookie?????????????,????????????
• ????cookie??????,???????????????cookie?,??,?????co
  okie????????????
• Cookie??????????????
• ?????IP?????????????,????????????hash?????

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ISAKMP?????

• ISAKMP???5???????
• Base Exchange
• ????,?????????
• Identity Protection Exchange
• ????,???????
• Authentication Only Exchange
• ????(??????)
• Aggressive Exchange
• ??????,???base exchange
• Informational Exchange
• ????,??SA??

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IKE?????

• PFS Perfect Forward Secrecy
• ?????????,???????????????
• Phase
• ?ISAKMP??phase
• Group
• Oakley???Diffie-Hellman??????
• Mode
• ??Oakley????
• ?????????
• ??mode
• Main Mode, Aggressive Mode??phase 1
• Quick Mode??phase 2
• New Group Mode??phase 1??,?????????????

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IKE???

• IKE??????(Diffie Helman????)
• 768-bit MODP group
• ??q 2768 - 2 704 - 1 264 2638 pi
  149686
• a 2
• 1024-bit MODP group
• ??q 21024 - 2960 - 1 264 2894 pi
  129093
• a 2
• EC2N group on GP2155
• EC2N group on GP2185

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IKE??????Main Mode

• ?ISAKMP?Identity Protection Exchange?????I -gt R
  SAR -gt I SAI -gt R KE NONCER -gt I KE
  NONCEI -gt R IDI AUTH (????) R -gt I IDR AUTH
  (????)
• ?????????
• ?????????????
• ????????Diffie-Hellman Exchange
• ??phase 1

32
IKE??????Aggressive Mode

• ?ISAKMP?Aggressive Exchange?????I -gt R SA KE
  NONCE IDIR -gt I SA KE NONCE IDR AUTHI -gt
  R AUTH (????)
• ?????????,??Diffie-Hellman????,?????????,?????
• ???????????
• ??????????
• ??phase 1

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IKE Phase 1??????

• IKE Phase 1 Authenticated With Signatures
• Phase 1 Authenticated With Public Key Encryption
• Phase 1 Authenticated With a Pre-Shared Key

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IKE??????Quick Mode

• ?ISAKMP??????????I -gt R SA NONCE IDI, IDR,
  KE HASH(1)R -gt I SA NONCE IDI, IDR, KE
  HASH(2)I -gt R HASH(3)??????????
• ??PFS?????,?????KE
• ???????

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IKE??????New Group Mode

• ?ISAKMP??????????I -gt R SA HASH(1)R -gt I SA
  HASH(2)??????????
• ????????

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IPSec?IKE??

• IPSec???????????
• ???????AH?ESP
• IKE?????????
• ??ISAKMP????????Oakley?SKEME??????????
• ??SA????????
• ??????Internet??
• ????
• IPSec???
• ?????,????????????
• ???????,???????
• ???????
• ??DOS,?????????????????
• ???????

37
IPSec??

• ????????
• ??CISCO?
• ??????
• ??Linux???UNIX??
• IPv6??
• ??VPN???

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Windows 2000?XP??IPSec

• ??
• http//online.securityfocus.com/infocus/1519
• http//online.securityfocus.com/infocus/1526
• http//online.securityfocus.com/infocus/1528
• ????
• ?IETF??
• ??Kerberos??????????????????
• ????IPSec?????????????RSVP??IKE??Kerberos?
• ?L2TP?????????VPN????
• ???NAT????
• ????????DOS,?????????
• ??FreeBSD???http//www.freebsd.org/doc/en_US.ISO8
  859-1/books/handbook/ipsec.html

39
Windows 2000?XP??IPSec????

• IPSec Security Policies snap-in for the MMC
  (secpol.msc)

40
??????

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

41
??????

• ????????

42
??????

• ????????

?????
?????
43
PKI???

• ????
• ??????????
• ??????????
• ???????????
• ??????????????
• ??????
• ??????(certificate)
• ??????????????

44
??????
45
PKI(Public Key Infrastructure)

• ??
• ??????????????????????????????
• ?????PKI????
• ????(CA)
• ???
• ????
• ???????
• ??????
• ??????
• ????
• ??????
• ???
• ?????

46
PKI???????

• ??
• ????????,????????????
• ?????? ???????
• ????????? ??????
• ???????challenge?? ????
• ???
• PKI???????
• ????????????,?????????
• MAC(?????)?DES-CBC-MAC??HMAC-MD5
• ???
• ?????????,????????????
• ????
• ???????? ????
• ???????? ?? ????

47
PKI?????

• ????????????,?????
• ??
• ???????????,????,??????????,?????????????
• ?????????????????,?????MAC??HMAC?????????
• ???????
• ???????????????
• ???????????????????
• ????????????????????
• ????????????
• ??????????,??????????
• ????
• ??????????,???CA?????????

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PKI????

• RA(Registration Authority)
• ?????????????????????
• CA(Certificate Authority)
• ??
• ???/??
• ????,?????

49
???????

• ??????,???????
• ??,??????????????
• PKI??????
• CA????CRL(Certificate Revocation List)
• ??Web?CRL??
• ??CRL?URL???????????
• ????????(SSL)??URL
• ????????
• ???????????

50
PKI????

• ??(certificate),??????cert
• PKI????????,???????????????????
• ???????????????????,??????????????????
• ?????,?????????????????????????????
• ???????????
• ?????????X.509 v3

51
X.509????

• ??1?2?3
• ???
• ?CA????
• ???????
• ??????????
• ?????
• CA???
• ????
• ???????
• ????

52
X.509????(?)

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

53
X.509?????
54
CA(Certificate Authority)

• ??
• ???????
• (?RA??????????????)
• ??????????
• ??????
• ????????
• ???????
• ??????????

55
???????
Password??
Help!!
?
??????
?????( ???)
56
CA????

• ?????

Sep 1998
Oct 1998
Nov 1998
Dec 1998
Jan 1999
Feb 1999
Mar 1999
Apr 1999
May 1999
Jun 1999
Jul 1999
Aug 1999
CA????????????????PKI????
57
CA????

• ??????????????????????,?????????
• ??????,??????????
• ??CA
• ????????CA??????????????-?????????,???????CA,?CA
  ???CA
• ????
• ???????????
• ????
• ???????????

58
CA????

• ??????CA?????????,??????????????CA???
• ???????CA????

59
CA???????

• ?CA??????????
• ?CA???????CA????
• ???????????CA???????????
• ??????,??????CA,???CA??????(???)???????????CA???
• ?CA????,??????
• ?????CA?,??????cert(1) Forward Certificates
  ??CA????certs(2) Reverse Certificates
  ?????CA?certs

60
????CA??????

• ????A??B?????
• B????????????CA???
• ????????,?????????,?????
• ????
• ??????,??????,??????????????????,????????,????????
  ???
• ?????B???????
• ????????????,?A??????????????,??????CA,??????B????
  ??
• ??????????

61
????????
62
????

• ?????CA??????????????
• ??????
• ??CA???????CA?????????????????????
• ??????
• ????????
• ??????(?????????)
• ??????(?????????)
• ???????
• ????
• ??????
• ????

63
???????????

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

64
?????????????PGP
65
?PKI???????

• Certificates X.509 v.3
• ???? PKIX group in IETF(RFC 2459)
• ???/???? PKCS 11
• PKCS??
• ????LDAP

66
PKCS????

• PKCS 1
• RSA Encryption Standard
• PKCS 3
• Diffie-Hellman Key-Agreement Standard
• PKCS 5
• Password-Based Encryption Standard
• PKCS 6
• Extended-Certificate Syntax Standard
• PKCS 7
• Cryptographic Message Syntax Standard
• PKCS 8
• Private-Key Information Syntax Standard

67
PKCS????(?)

• PKCS 9
• Selected Attribute Types
• PKCS 10
• Certification Request Syntax Standard
• PKCS 11
• Cryptographic Token Interface Standard
• PKCS 12
• Personal Information Exchange Standard
• PKCS 13
• Elliptic Curve Cryptography Standard
• PKCS 15
• Cryptographic Token Information Format Standard

68
????Web??????
PKCS10
69
CA??????
PKCS7
70
PKI??

• ?????
• ????
• E-mail
• Web??
• ??
• VPN
• SSL/TLS
• XML/e-business
• WAP

71
PKI?????

• ?????PKI
• ????PKI
• ??????PKI??
• ??????PKI
• PKI???????,????

72
Windows 2000??PKI

• Windows 2000?????????

73
Windows 2000???????
74
Windows 2000?,????????
75
????

• ?
• William Stallings, Cryptography and network
  security principles and practice, Second Edition
• ???,?????????,???????,2001
• David Chappell, Understanding Microsoft Windows
  2000 Distributed Services, ???(???????,????),
  2001
• ??
• RFC 2401, Security Architecture for the Internet
  Protocol
• RFC 2402, IP Authentication Header
• RFC 2406, IP Encapsulating Security Payload (ESP)
• RFC 2408, Internet Security Association and Key
  Management Protocol (ISAKMP)
• RFC 2409, The Internet Key Exchange(IKE)
• Web??
• RSA??,http//www.rsasecurity.com/