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Cryptography and Network security # Lecture 8
The document discusses the 3C-CSIRT model for cybersecurity, focusing on IP security (IPsec) to enhance network security for Afghanistan's Bakhtar University. It outlines IPsec's features, including authentication, integrity, confidentiality, and capabilities for securing communications across various networks. Additionally, it details the framework for key management and cryptographic algorithms, highlighting the importance of secure data transmission and prevention of unauthorized access.
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Cryptography and Network security # Lecture 8
- 1. Lec-8: Cryptography &Network Security Mr. Islahuddin Jalal MS (Cyber Security) – UKM Malaysia Research Title – 3C-CSIRT Model for Afghanistan BAKHTAR UNIVERSITY باخترپوهنتون د Bakhtar University پوهنتون باختر د 112/24/2017
- 2. Foundations • IP packetshave no inherent security • No way to verify • The claimed sender is the true sender • The data has not been modified in transit • The data has not been viewed by a third party • Ipsec provides an automated solution for these three areas • Authentication • Integrity • confidentiality 2
- 3. IP Security • Capabilityadded to IPv4 and IPv6 by means of additional headers • IPsec provides: • Authentication • Confidentiality • Key management 3
- 4. IP security Overview •In 1994, IAB report “Security in the Internet Architecture” • Identified Key areas for security Mechanisms • Secure the network infrastructure • Unauthorized monitoring • Unauthorized Control of network traffic • Secure end-user-to-end-user traffic 4
- 5. Application of IPsec •Provides the capability to secure communications • Across a LAN • Across private and Public WANs • Across the Internet 5
- 6. Examples of IPsecuse • Secure branch office connectivity over the internet • Secure remote access over the Internet • Establishing extranet and intranet connectivity with partners • Enhancing electronic commerce security 6
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- 8. Benefits of IPSec ina firewall/router provides strong security to all traffic crossing the perimeter in a firewall/router is resistant to bypass can be transparent to end users can provide security for individual users secures routing architecture
- 9. IP Security Architecture •specification is quite complex, with groups: • Architecture • RFC4301 Security Architecture for Internet Protocol • Authentication Header (AH) • RFC4302 IP Authentication Header • Encapsulating Security Payload (ESP) • RFC4303 IP Encapsulating Security Payload (ESP) • Internet Key Exchange (IKE) • RFC4306 Internet Key Exchange (IKEv2) Protocol • Cryptographic algorithms • Other
- 10. IPSec Services • Accesscontrol • Connectionless integrity • Data origin authentication • Rejection of replayed packets • a form of partial sequence integrity • Confidentiality (encryption) • Limited traffic flow confidentiality
- 11. Transport and TunnelModes • Transport Mode • to encrypt & optionally authenticate IP data • 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 • no routers on way can examine inner IP header • good for VPNs, gateway to gateway security
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- 14. Security Associations • aone-way relationship between sender & receiver that affords security services to the traffic carried on it. • 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
- 15. Security Policy Database relatesIP traffic to specific SAs match subset of IP traffic to relevant SA use selectors to filter outgoing traffic to map based on: local & remote IP addresses, next layer protocol, name, local & remote ports
- 16. Encapsulating Security Payload(ESP) • provides message content confidentiality, data origin authentication, connectionless integrity, an anti-replay service, limited traffic flow confidentiality • services depend on options selected when establish Security Association (SA), net location • can use a variety of encryption & authentication algorithms
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- 18. Encryption & Authentication Algorithms& Padding • ESP can encrypt payload data, padding, pad length, and next header fields • if needed have IV at start of payload data • ESP can have optional ICV for integrity • is computed after encryption is performed • ESP uses padding • to expand plaintext to required length • to align pad length and next header fields • to provide partial traffic flow confidentiality
- 19. Anti-Replay Service • replayis when attacker resends a copy of an authenticated packet • use sequence number to thwart(prevent) this attack • sender initializes sequence number to 0 when a new SA is established • increment for each packet • must not exceed limit of 232 – 1 • receiver then accepts packets with seq no within window of (N –W+1)
- 20. Combining Security Associations •SA’s can implement either AH or ESP • to implement both need to combine SA’s • form a security association bundle • may terminate at different or same endpoints • combined by • transport adjacency • iterated tunneling • combining authentication & encryption • ESP with authentication, bundled inner ESP & outer AH, bundled inner transport & outer ESP
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- 22. IPSec 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
- 23. Oakley • a keyexchange protocol • based on Diffie-Hellman key exchange • adds features to address weaknesses • no info on parties, man-in-middle attack, cost • so adds cookies, groups (global params), nonces, DH key exchange with authentication • can use arithmetic in prime fields or elliptic curve fields
- 24. ISAKMP • Internet SecurityAssociation 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 • IKEv2 no longer uses Oakley & ISAKMP terms, but basic functionality is same
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- 27. IKE Payloads &Exchanges have a number of ISAKMP payload types: Security Association, Key Exchange, Identification, Certificate, Certificate Request, Authentication, Nonce, Notify, Delete, Vendor ID, Traffic Selector, Encrypted, Configuration, Extensible Authentication Protocol payload has complex hierarchical structure may contain multiple proposals, with multiple protocols & multiple transforms
- 28. Cryptographic Suites • varietyof cryptographic algorithm types • to promote interoperability have • RFC4308 defines VPN cryptographic suites • VPN-A matches common corporate VPN security using 3DES & HMAC • VPN-B has stronger security for new VPNs implementing IPsecv3 and IKEv2 using AES • RFC4869 defines four cryptographic suites compatible with US NSA specs • provide choices for ESP & IKE • AES-GCM, AES-CBC, HMAC-SHA, ECP, ECDSA
- 29. Thank You For YourPatience 12/24/2017 Bakhtar University پوهنتون باختر د 29