SlideShare a Scribd company logo
Cryptography and Network
Security
IP Security
• have considered some application specific
security mechanisms
– eg. S/MIME, PGP, Kerberos, SSL/HTTPS
• however there are security concerns that
cut across protocol layers
• would like security implemented by the
network for all applications
IPSec
• general IP Security mechanisms
• provides
– authentication
– confidentiality
– key management
• applicable to use over LANs, across public
& private WANs, & for the Internet
IPSec Uses
Benefits of IPSec
• in a firewall/router provides strong security
to all traffic crossing the perimeter
• is resistant to bypass
• is below transport layer, hence transparent
to applications
• can be transparent to end users
• can provide security for individual users if
desired
IP Security Architecture
• specification is quite complex
• defined in numerous RFC’s
– incl. RFC 2401/2402/2406/2408
– many others, grouped by category
• mandatory in IPv6, optional in IPv4
IPSec Services
• Access control
• Connectionless integrity
• Data origin authentication
• Rejection of replayed packets
– a form of partial sequence integrity
• Confidentiality (encryption)
• Limited traffic flow confidentiality
Security Associations
• a one-way relationship between sender &
receiver that affords security for traffic flow
• defined by 3 parameters:
– Security Parameters Index (SPI)
– IP Destination Address
– Security Protocol Identifier
• has a number of other parameters
– seq no, AH & EH info, lifetime etc
• have a database of Security Associations
Authentication Header (AH)
• provides support for data integrity &
authentication of IP packets
– end system/router can authenticate user/app
– prevents address spoofing attacks by tracking
sequence numbers
• based on use of a MAC
– HMAC-MD5-96 or HMAC-SHA-1-96
• parties must share a secret key
Authentication Header
Transport & Tunnel Modes
Encapsulating Security Payload
(ESP)
• provides message content confidentiality &
limited traffic flow confidentiality
• can optionally provide the same
authentication services as AH
• supports range of ciphers, modes, padding
– incl. DES, Triple-DES, RC5, IDEA, CAST etc
– CBC most common
– pad to meet blocksize, for traffic flow
Encapsulating Security Payload
Transport vs Tunnel Mode ESP
• transport mode is used to encrypt &
optionally authenticate IP data
– data protected but header left in clear
– can do traffic analysis but is efficient
– good for ESP host to host traffic
• tunnel mode encrypts entire IP packet
– add new header for next hop
– good for VPNs, gateway to gateway security
Combining Security Associations
• SA’s can implement either AH or ESP
• to implement both need to combine SA’s
– form a security bundle
• have 4 cases (see next)
Combining Security Associations
Key Management
• handles key generation & distribution
• typically need 2 pairs of keys
– 2 per direction for AH & ESP
• manual key management
– sysadmin manually configures every system
• automated key management
– automated system for on demand creation of
keys for SA’s in large systems
– has Oakley & ISAKMP elements
Oakley
• a key exchange protocol
• based on Diffie-Hellman key exchange
• adds features to address weaknesses
– cookies, groups (global params), nonces, DH
key exchange with authentication
• can use arithmetic in prime fields or elliptic
curve fields
ISAKMP
• Internet Security Association and Key
Management Protocol
• provides framework for key management
• defines procedures and packet formats to
establish, negotiate, modify, & delete SAs
• independent of key exchange protocol,
encryption alg, & authentication method
ISAKMP
Summary
• have considered:
– IPSec security framework
– AH
– ESP
– key management & Oakley/ISAKMP

More Related Content

Similar to Unit 5.ppt

CS6701 CRYPTOGRAPHY AND NETWORK SECURITY
CS6701 CRYPTOGRAPHY AND NETWORK SECURITYCS6701 CRYPTOGRAPHY AND NETWORK SECURITY
CS6701 CRYPTOGRAPHY AND NETWORK SECURITY
Kathirvel Ayyaswamy
 
Telecommunications and Network Security Presentation
Telecommunications and Network Security PresentationTelecommunications and Network Security Presentation
Telecommunications and Network Security PresentationWajahat Rajab
 
Vpn(virtual private network)
Vpn(virtual private network)Vpn(virtual private network)
Vpn(virtual private network)
sonangrai
 
IP Protocol Security
IP Protocol SecurityIP Protocol Security
IP Protocol SecurityDavid Barker
 
18CS2005 Cryptography and Network Security
18CS2005 Cryptography and Network Security18CS2005 Cryptography and Network Security
18CS2005 Cryptography and Network Security
Kathirvel Ayyaswamy
 
IS Unit-4 .ppt
IS Unit-4 .pptIS Unit-4 .ppt
IS Unit-4 .ppt
NamanRockzz
 
Ip sec and ssl
Ip sec and  sslIp sec and  ssl
Ip sec and sslMohd Arif
 
CS6004 CYBER FORENSICS
CS6004 CYBER FORENSICS CS6004 CYBER FORENSICS
CS6004 CYBER FORENSICS
Kathirvel Ayyaswamy
 
ICS PPT Unit 4.ppt
ICS PPT Unit 4.pptICS PPT Unit 4.ppt
ICS PPT Unit 4.ppt
DEEPAK948083
 
ssl-tls-ipsec-vpn.pptx
ssl-tls-ipsec-vpn.pptxssl-tls-ipsec-vpn.pptx
ssl-tls-ipsec-vpn.pptx
jithu26327
 
501 ch 4 securing your network
501 ch 4 securing your network501 ch 4 securing your network
501 ch 4 securing your network
gocybersec
 
Module 8 - Ccna - Pre.pptx
Module 8 - Ccna - Pre.pptxModule 8 - Ccna - Pre.pptx
Module 8 - Ccna - Pre.pptx
AliMohamed855266
 
CS6004 CYBER FORENSICS
CS6004 CYBER FORENSICS CS6004 CYBER FORENSICS
CS6004 CYBER FORENSICS
Kathirvel Ayyaswamy
 
SECURE SOCKET LAYER(SSL)_LECTURE SLIDES.pdf
SECURE SOCKET LAYER(SSL)_LECTURE SLIDES.pdfSECURE SOCKET LAYER(SSL)_LECTURE SLIDES.pdf
SECURE SOCKET LAYER(SSL)_LECTURE SLIDES.pdf
NiharikaDubey17
 
IP Security
IP SecurityIP Security
IP Security
Dr.Florence Dayana
 
ch22.ppt
ch22.pptch22.ppt
ch22.ppt
ImXaib
 
IP security and VPN presentation
IP security and VPN presentation IP security and VPN presentation
IP security and VPN presentation
KishoreTs3
 
08. networking-part-2
08. networking-part-208. networking-part-2
08. networking-part-2
Muhammad Ahad
 
CRYPTOGRAPHY AND NETWORK SECURITY- E-Mail Security
CRYPTOGRAPHY AND NETWORK SECURITY- E-Mail SecurityCRYPTOGRAPHY AND NETWORK SECURITY- E-Mail Security
CRYPTOGRAPHY AND NETWORK SECURITY- E-Mail Security
Jyothishmathi Institute of Technology and Science Karimnagar
 

Similar to Unit 5.ppt (20)

CS6701 CRYPTOGRAPHY AND NETWORK SECURITY
CS6701 CRYPTOGRAPHY AND NETWORK SECURITYCS6701 CRYPTOGRAPHY AND NETWORK SECURITY
CS6701 CRYPTOGRAPHY AND NETWORK SECURITY
 
Telecommunications and Network Security Presentation
Telecommunications and Network Security PresentationTelecommunications and Network Security Presentation
Telecommunications and Network Security Presentation
 
Vpn(virtual private network)
Vpn(virtual private network)Vpn(virtual private network)
Vpn(virtual private network)
 
IP Protocol Security
IP Protocol SecurityIP Protocol Security
IP Protocol Security
 
18CS2005 Cryptography and Network Security
18CS2005 Cryptography and Network Security18CS2005 Cryptography and Network Security
18CS2005 Cryptography and Network Security
 
Ch16
Ch16Ch16
Ch16
 
IS Unit-4 .ppt
IS Unit-4 .pptIS Unit-4 .ppt
IS Unit-4 .ppt
 
Ip sec and ssl
Ip sec and  sslIp sec and  ssl
Ip sec and ssl
 
CS6004 CYBER FORENSICS
CS6004 CYBER FORENSICS CS6004 CYBER FORENSICS
CS6004 CYBER FORENSICS
 
ICS PPT Unit 4.ppt
ICS PPT Unit 4.pptICS PPT Unit 4.ppt
ICS PPT Unit 4.ppt
 
ssl-tls-ipsec-vpn.pptx
ssl-tls-ipsec-vpn.pptxssl-tls-ipsec-vpn.pptx
ssl-tls-ipsec-vpn.pptx
 
501 ch 4 securing your network
501 ch 4 securing your network501 ch 4 securing your network
501 ch 4 securing your network
 
Module 8 - Ccna - Pre.pptx
Module 8 - Ccna - Pre.pptxModule 8 - Ccna - Pre.pptx
Module 8 - Ccna - Pre.pptx
 
CS6004 CYBER FORENSICS
CS6004 CYBER FORENSICS CS6004 CYBER FORENSICS
CS6004 CYBER FORENSICS
 
SECURE SOCKET LAYER(SSL)_LECTURE SLIDES.pdf
SECURE SOCKET LAYER(SSL)_LECTURE SLIDES.pdfSECURE SOCKET LAYER(SSL)_LECTURE SLIDES.pdf
SECURE SOCKET LAYER(SSL)_LECTURE SLIDES.pdf
 
IP Security
IP SecurityIP Security
IP Security
 
ch22.ppt
ch22.pptch22.ppt
ch22.ppt
 
IP security and VPN presentation
IP security and VPN presentation IP security and VPN presentation
IP security and VPN presentation
 
08. networking-part-2
08. networking-part-208. networking-part-2
08. networking-part-2
 
CRYPTOGRAPHY AND NETWORK SECURITY- E-Mail Security
CRYPTOGRAPHY AND NETWORK SECURITY- E-Mail SecurityCRYPTOGRAPHY AND NETWORK SECURITY- E-Mail Security
CRYPTOGRAPHY AND NETWORK SECURITY- E-Mail Security
 

More from DHANABALSUBRAMANIAN

unit 2.ppt
unit 2.pptunit 2.ppt
Unit --3.ppt
Unit --3.pptUnit --3.ppt
Unit --3.ppt
DHANABALSUBRAMANIAN
 
Unit 4.ppt
Unit 4.pptUnit 4.ppt
Unit 1.ppt
Unit 1.pptUnit 1.ppt
Unit -- 5.ppt
Unit -- 5.pptUnit -- 5.ppt
Unit -- 5.ppt
DHANABALSUBRAMANIAN
 
Unit 3.ppt
Unit 3.pptUnit 3.ppt
Unit - 5.ppt
Unit - 5.pptUnit - 5.ppt
Unit - 5.ppt
DHANABALSUBRAMANIAN
 
Unit - 3.ppt
Unit - 3.pptUnit - 3.ppt
Unit - 3.ppt
DHANABALSUBRAMANIAN
 
unit -1.ppt
unit -1.pptunit -1.ppt
unit -1.ppt
DHANABALSUBRAMANIAN
 
Unit -2.ppt
Unit -2.pptUnit -2.ppt
Unit -2.ppt
DHANABALSUBRAMANIAN
 
OS UNIT1.pptx
OS UNIT1.pptxOS UNIT1.pptx
OS UNIT1.pptx
DHANABALSUBRAMANIAN
 
OS UNIT2.ppt
OS UNIT2.pptOS UNIT2.ppt
OS UNIT2.ppt
DHANABALSUBRAMANIAN
 
OS Unit5.pptx
OS Unit5.pptxOS Unit5.pptx
OS Unit5.pptx
DHANABALSUBRAMANIAN
 
OS UNIT4.pptx
OS UNIT4.pptxOS UNIT4.pptx
OS UNIT4.pptx
DHANABALSUBRAMANIAN
 
OS UNIT3.pptx
OS UNIT3.pptxOS UNIT3.pptx
OS UNIT3.pptx
DHANABALSUBRAMANIAN
 

More from DHANABALSUBRAMANIAN (15)

unit 2.ppt
unit 2.pptunit 2.ppt
unit 2.ppt
 
Unit --3.ppt
Unit --3.pptUnit --3.ppt
Unit --3.ppt
 
Unit 4.ppt
Unit 4.pptUnit 4.ppt
Unit 4.ppt
 
Unit 1.ppt
Unit 1.pptUnit 1.ppt
Unit 1.ppt
 
Unit -- 5.ppt
Unit -- 5.pptUnit -- 5.ppt
Unit -- 5.ppt
 
Unit 3.ppt
Unit 3.pptUnit 3.ppt
Unit 3.ppt
 
Unit - 5.ppt
Unit - 5.pptUnit - 5.ppt
Unit - 5.ppt
 
Unit - 3.ppt
Unit - 3.pptUnit - 3.ppt
Unit - 3.ppt
 
unit -1.ppt
unit -1.pptunit -1.ppt
unit -1.ppt
 
Unit -2.ppt
Unit -2.pptUnit -2.ppt
Unit -2.ppt
 
OS UNIT1.pptx
OS UNIT1.pptxOS UNIT1.pptx
OS UNIT1.pptx
 
OS UNIT2.ppt
OS UNIT2.pptOS UNIT2.ppt
OS UNIT2.ppt
 
OS Unit5.pptx
OS Unit5.pptxOS Unit5.pptx
OS Unit5.pptx
 
OS UNIT4.pptx
OS UNIT4.pptxOS UNIT4.pptx
OS UNIT4.pptx
 
OS UNIT3.pptx
OS UNIT3.pptxOS UNIT3.pptx
OS UNIT3.pptx
 

Recently uploaded

How libraries can support authors with open access requirements for UKRI fund...
How libraries can support authors with open access requirements for UKRI fund...How libraries can support authors with open access requirements for UKRI fund...
How libraries can support authors with open access requirements for UKRI fund...
Jisc
 
Sha'Carri Richardson Presentation 202345
Sha'Carri Richardson Presentation 202345Sha'Carri Richardson Presentation 202345
Sha'Carri Richardson Presentation 202345
beazzy04
 
Fish and Chips - have they had their chips
Fish and Chips - have they had their chipsFish and Chips - have they had their chips
Fish and Chips - have they had their chips
GeoBlogs
 
How to Split Bills in the Odoo 17 POS Module
How to Split Bills in the Odoo 17 POS ModuleHow to Split Bills in the Odoo 17 POS Module
How to Split Bills in the Odoo 17 POS Module
Celine George
 
The geography of Taylor Swift - some ideas
The geography of Taylor Swift - some ideasThe geography of Taylor Swift - some ideas
The geography of Taylor Swift - some ideas
GeoBlogs
 
TESDA TM1 REVIEWER FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
TESDA TM1 REVIEWER  FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...TESDA TM1 REVIEWER  FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
TESDA TM1 REVIEWER FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
EugeneSaldivar
 
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCECLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
BhavyaRajput3
 
special B.ed 2nd year old paper_20240531.pdf
special B.ed 2nd year old paper_20240531.pdfspecial B.ed 2nd year old paper_20240531.pdf
special B.ed 2nd year old paper_20240531.pdf
Special education needs
 
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
siemaillard
 
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
Nguyen Thanh Tu Collection
 
Introduction to Quality Improvement Essentials
Introduction to Quality Improvement EssentialsIntroduction to Quality Improvement Essentials
Introduction to Quality Improvement Essentials
Excellence Foundation for South Sudan
 
Language Across the Curriculm LAC B.Ed.
Language Across the  Curriculm LAC B.Ed.Language Across the  Curriculm LAC B.Ed.
Language Across the Curriculm LAC B.Ed.
Atul Kumar Singh
 
Overview on Edible Vaccine: Pros & Cons with Mechanism
Overview on Edible Vaccine: Pros & Cons with MechanismOverview on Edible Vaccine: Pros & Cons with Mechanism
Overview on Edible Vaccine: Pros & Cons with Mechanism
DeeptiGupta154
 
Sectors of the Indian Economy - Class 10 Study Notes pdf
Sectors of the Indian Economy - Class 10 Study Notes pdfSectors of the Indian Economy - Class 10 Study Notes pdf
Sectors of the Indian Economy - Class 10 Study Notes pdf
Vivekanand Anglo Vedic Academy
 
How to Make a Field invisible in Odoo 17
How to Make a Field invisible in Odoo 17How to Make a Field invisible in Odoo 17
How to Make a Field invisible in Odoo 17
Celine George
 
PART A. Introduction to Costumer Service
PART A. Introduction to Costumer ServicePART A. Introduction to Costumer Service
PART A. Introduction to Costumer Service
PedroFerreira53928
 
Instructions for Submissions thorugh G- Classroom.pptx
Instructions for Submissions thorugh G- Classroom.pptxInstructions for Submissions thorugh G- Classroom.pptx
Instructions for Submissions thorugh G- Classroom.pptx
Jheel Barad
 
Additional Benefits for Employee Website.pdf
Additional Benefits for Employee Website.pdfAdditional Benefits for Employee Website.pdf
Additional Benefits for Employee Website.pdf
joachimlavalley1
 
Polish students' mobility in the Czech Republic
Polish students' mobility in the Czech RepublicPolish students' mobility in the Czech Republic
Polish students' mobility in the Czech Republic
Anna Sz.
 
The French Revolution Class 9 Study Material pdf free download
The French Revolution Class 9 Study Material pdf free downloadThe French Revolution Class 9 Study Material pdf free download
The French Revolution Class 9 Study Material pdf free download
Vivekanand Anglo Vedic Academy
 

Recently uploaded (20)

How libraries can support authors with open access requirements for UKRI fund...
How libraries can support authors with open access requirements for UKRI fund...How libraries can support authors with open access requirements for UKRI fund...
How libraries can support authors with open access requirements for UKRI fund...
 
Sha'Carri Richardson Presentation 202345
Sha'Carri Richardson Presentation 202345Sha'Carri Richardson Presentation 202345
Sha'Carri Richardson Presentation 202345
 
Fish and Chips - have they had their chips
Fish and Chips - have they had their chipsFish and Chips - have they had their chips
Fish and Chips - have they had their chips
 
How to Split Bills in the Odoo 17 POS Module
How to Split Bills in the Odoo 17 POS ModuleHow to Split Bills in the Odoo 17 POS Module
How to Split Bills in the Odoo 17 POS Module
 
The geography of Taylor Swift - some ideas
The geography of Taylor Swift - some ideasThe geography of Taylor Swift - some ideas
The geography of Taylor Swift - some ideas
 
TESDA TM1 REVIEWER FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
TESDA TM1 REVIEWER  FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...TESDA TM1 REVIEWER  FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
TESDA TM1 REVIEWER FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
 
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCECLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
 
special B.ed 2nd year old paper_20240531.pdf
special B.ed 2nd year old paper_20240531.pdfspecial B.ed 2nd year old paper_20240531.pdf
special B.ed 2nd year old paper_20240531.pdf
 
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
 
Introduction to Quality Improvement Essentials
Introduction to Quality Improvement EssentialsIntroduction to Quality Improvement Essentials
Introduction to Quality Improvement Essentials
 
Language Across the Curriculm LAC B.Ed.
Language Across the  Curriculm LAC B.Ed.Language Across the  Curriculm LAC B.Ed.
Language Across the Curriculm LAC B.Ed.
 
Overview on Edible Vaccine: Pros & Cons with Mechanism
Overview on Edible Vaccine: Pros & Cons with MechanismOverview on Edible Vaccine: Pros & Cons with Mechanism
Overview on Edible Vaccine: Pros & Cons with Mechanism
 
Sectors of the Indian Economy - Class 10 Study Notes pdf
Sectors of the Indian Economy - Class 10 Study Notes pdfSectors of the Indian Economy - Class 10 Study Notes pdf
Sectors of the Indian Economy - Class 10 Study Notes pdf
 
How to Make a Field invisible in Odoo 17
How to Make a Field invisible in Odoo 17How to Make a Field invisible in Odoo 17
How to Make a Field invisible in Odoo 17
 
PART A. Introduction to Costumer Service
PART A. Introduction to Costumer ServicePART A. Introduction to Costumer Service
PART A. Introduction to Costumer Service
 
Instructions for Submissions thorugh G- Classroom.pptx
Instructions for Submissions thorugh G- Classroom.pptxInstructions for Submissions thorugh G- Classroom.pptx
Instructions for Submissions thorugh G- Classroom.pptx
 
Additional Benefits for Employee Website.pdf
Additional Benefits for Employee Website.pdfAdditional Benefits for Employee Website.pdf
Additional Benefits for Employee Website.pdf
 
Polish students' mobility in the Czech Republic
Polish students' mobility in the Czech RepublicPolish students' mobility in the Czech Republic
Polish students' mobility in the Czech Republic
 
The French Revolution Class 9 Study Material pdf free download
The French Revolution Class 9 Study Material pdf free downloadThe French Revolution Class 9 Study Material pdf free download
The French Revolution Class 9 Study Material pdf free download
 

Unit 5.ppt

  • 2. IP Security • have considered some application specific security mechanisms – eg. S/MIME, PGP, Kerberos, SSL/HTTPS • however there are security concerns that cut across protocol layers • would like security implemented by the network for all applications
  • 3. IPSec • general IP Security mechanisms • provides – authentication – confidentiality – key management • applicable to use over LANs, across public & private WANs, & for the Internet
  • 5. Benefits of IPSec • in a firewall/router provides strong security to all traffic crossing the perimeter • is resistant to bypass • is below transport layer, hence transparent to applications • can be transparent to end users • can provide security for individual users if desired
  • 6. IP Security Architecture • specification is quite complex • defined in numerous RFC’s – incl. RFC 2401/2402/2406/2408 – many others, grouped by category • mandatory in IPv6, optional in IPv4
  • 7. IPSec Services • Access control • Connectionless integrity • Data origin authentication • Rejection of replayed packets – a form of partial sequence integrity • Confidentiality (encryption) • Limited traffic flow confidentiality
  • 8. Security Associations • a one-way relationship between sender & receiver that affords security for traffic flow • defined by 3 parameters: – Security Parameters Index (SPI) – IP Destination Address – Security Protocol Identifier • has a number of other parameters – seq no, AH & EH info, lifetime etc • have a database of Security Associations
  • 9. Authentication Header (AH) • provides support for data integrity & authentication of IP packets – end system/router can authenticate user/app – prevents address spoofing attacks by tracking sequence numbers • based on use of a MAC – HMAC-MD5-96 or HMAC-SHA-1-96 • parties must share a secret key
  • 12. Encapsulating Security Payload (ESP) • provides message content confidentiality & limited traffic flow confidentiality • can optionally provide the same authentication services as AH • supports range of ciphers, modes, padding – incl. DES, Triple-DES, RC5, IDEA, CAST etc – CBC most common – pad to meet blocksize, for traffic flow
  • 14. Transport vs Tunnel Mode ESP • transport mode is used to encrypt & optionally authenticate IP data – data protected but header left in clear – can do traffic analysis but is efficient – good for ESP host to host traffic • tunnel mode encrypts entire IP packet – add new header for next hop – good for VPNs, gateway to gateway security
  • 15. Combining Security Associations • SA’s can implement either AH or ESP • to implement both need to combine SA’s – form a security bundle • have 4 cases (see next)
  • 17. Key Management • handles key generation & distribution • typically need 2 pairs of keys – 2 per direction for AH & ESP • manual key management – sysadmin manually configures every system • automated key management – automated system for on demand creation of keys for SA’s in large systems – has Oakley & ISAKMP elements
  • 18. Oakley • a key exchange protocol • based on Diffie-Hellman key exchange • adds features to address weaknesses – cookies, groups (global params), nonces, DH key exchange with authentication • can use arithmetic in prime fields or elliptic curve fields
  • 19. ISAKMP • Internet Security Association and Key Management Protocol • provides framework for key management • defines procedures and packet formats to establish, negotiate, modify, & delete SAs • independent of key exchange protocol, encryption alg, & authentication method
  • 21. Summary • have considered: – IPSec security framework – AH – ESP – key management & Oakley/ISAKMP