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Agenda

Network Layer Security Howie Weiss ( NASA/JPL/ SPARTA / Cobham /Parsons) Boulder, CO November 2011. Agenda . CCSDS Network Layer Security IPSec+IKE Profile for CCSDS What is included? What is excluded? How is it used ? Review WG results from Berlin meeting.

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Agenda

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  1. Network Layer SecurityHowie Weiss(NASA/JPL/SPARTA/Cobham/Parsons)Boulder, CONovember 2011

  2. Agenda • CCSDS Network Layer Security • IPSec+IKE Profile for CCSDS • What is included? • What is excluded? • How is it used? • Review WG results from Berlin meeting

  3. What is Network Layer Security? Space extensions to FTP Other Apps SCPS-FP FTP Features FTP Space extensions to the Socket Interface SCPS-TP “TCP Tranquility” options TCP Options TCP UDP Space-optimized IPSec variant IPSec SCPS-SP IKE Common Network- Layer Interface Space-optimized IP variant IP SCPS-NP Space Link Subnet: CCSDS Data Link

  4. IPSec: one protocol, many options • Tunnel mode vs. transport mode • Default cipher suite (encryption + auth + mode) • Authenticated encryption? • Null encryption (authentication-only)? • ESP w/null encrypt or AH? • What would be allowed? • Anti-replay option • Keying and rekeying • Pre-placed keys? • IKE auto rekey • Automatic when keys expire – regardless of mission state? • Rekey “now” button?

  5. Issues to be resolved • Transport or tunnel mode or both? • Tunnel mode • ESP-only? AH-only? • ESP-only • ESP + AH? • No • Authentication-only w/o encryption allowed? (null encryption) • Yes • Authenticated Encryption or Encryption w/o auth allowed? • AEAD Yes, warning that encryption-only is unsafe • Keying and rekeying questions • Automated vs. manual • IKEv1 or IKEv2 • IKEv2 w/rekey commanding “button” • Push-to-rekey • Push-to-inhibit rekey • Manual keying allowed • SA lifetimes • Policy Management • Silent for now • Define default cipher suite(s) • Follow algorithm document + IKE & IPsec RFCs • Compression • Optional IPcomp

  6. Transport vs. Tunnel Mode • Transport Mode: • Single IP header • End-to-End mode (writer-2-reader) • Not generally used commercially • Tunnel Mode: • Dual IP headers – entire IP packet is encapsulated • Allows Gateway-to-Gateway mode • Allows IPSec to be outboard in security gateways • E.g., commercial VPNs • Recommendation for CCSDS: • Tunnel Mode

  7. IPSec is TWO Protocols • AH: IP Authentication Header (RFC 4302) • connectionless integrity • data origin authentication. • optional replay protection • No confidentiality • ESP: Encapsulating Security Payload (RFC 4303) • confidentiality, • data origin authentication, • connectionless integrity, • anti-replay protection (w/automated key management), • limited traffic flow confidentiality. • Provides encryption-only service for confidentiality • Provides integrity-only service • Provides confidentiality + integrity service

  8. AH Packet Format AH (IP protocol 51) total length 152 bytes AH Authenticated (108 bytes)

  9. ESP w/Null Encryption ESP (IP protocol 50) total length 152 bytes ESP Header ESP Trailer ESP Auth ESP Authenticated (132 bytes)

  10. ESP w/AES-GCM ESP (IP protocol 50) total length 160 bytes Encrypted (128 bytes) ESP Header ESP Trailer ESP Auth ESP Authenticated (140 bytes)

  11. ESP w/AES-GCM + AH AH (IP protocol 51) total length 184 bytes AH Authenticated (148 bytes) Encrypted (128 bytes) ESP Header ESP Trailer ESP Auth ESP Authenticated (140 bytes)

  12. ESP and/or AH ? • AH does not support confidentiality • ESP supports both confidentiality and integrity • Supports null encryption • AH was designed because of export control issues regarding encryption algorithms • AH and ESP can be nested but why? • Too much overhead • Recommendation for CCSDS: • ESP-only

  13. Security Services Allowed • Authentication-only mode • CCSDS Recommendation: allow • Needed for commanding w/o need for confidentiality • Authenticated Encryption mode • CCSDS Recommendation: allow (must) • Encryption w/o authentication is shown to be a dangerous practice • Non-authenticated Encryption mode • CCSDS Recommendation: unsafe, not recommended • Operational overhead and mission risk analysis may have need for this but it should not be done without analysis

  14. Keying • Conformant IPSec must support BOTH automated and manual keying • Automated keying: Internet Key Exchange • Manual keying: ad-hoc (each implementation determines how) • Issues regarding automated keying: • Rekey at “bad” time in the mission timeline • E.g., critical burn maneuver • E.g., critical upload/download • Requires little human intervention • Issues regarding manual keying: • “simple” but requires human resources • Physical distribution and protection required

  15. Internet Key Exchange (IKE) • IKE v1 (RFC 2409) • Complicated, robust protocol • Commercially widely used • IKE v2 (RFC 4306) • Simpler than IKEv1 (maybe safer…) • Commercially not widely used, yet. • Requires on-board flight code • More flight code to certify • But do it once and reuse, reuse, reuse

  16. IKE Operation • IKE rekeys when thresholds are met, for example: • Number of bytes transmitted • Elapsed time • For space, IKE Rekey-Upon-Command is needed • E.g., button-push to rekey • E.g., button-push to inhibit rekey • For space, timers will have to be tweaked vs. commercial (terrestrial) implementations • Recommendation for CCSDS: • IKEv2 w/rekey commanding “button” • Push-to-rekey • Push-to-inhibit rekey rekey

  17. Manual Keying • Sometimes simple is enough…. • Need ability to preload keys (e.g., 512 keys, 1024 keys) onboard • Maybe have a key upload ability? • Command to change keys • Preload and manage Security Associations (SA) • Recommendation for CCSDS: • Require manual key w/management (testing, ground checkout) 110010110010011100110110

  18. Policy Management • IPSec supports policies, e.g.: • Security services on a connection • Access controls for connection • No standards for loading, updating, supporting IPSec policies • SNMP-based approaches: • RFC 4807: IPSec Security Policy Database Configuration MIB • IPSec Security Policy IPSec Action MIB (IETF draft) • IPSec Security Policy IKE Action MIB (IETF draft) • Microsoft IPSec Policy Agent Service • KeyNote, ipsecconf, proprietary, etc • What do we want to do?

  19. Cipher Suite • Follow CCSDS Algorithms document • 128-bit key size • AES • AES-GCM for authenticated encryption • AES-CMAC, AES-GMAC, HMAC for authentication/integrity

  20. Compression • Overhead vs. Bandwidth! • IPSec adds overhead • Everyone complains about not having enough bandwidth • IP Payload Compression Protocol (IPComp) (RFC 3173) • Commercially supported • Compresses IP datagrams BEFORE security processing on outbound • Decompresses IP datagrams AFTER security processing on inbound • Recommendation for CCSDS: • Optional use of IPComp

  21. Summary • IPSec: ESP-only • Null encryption allowed • Authenticated encryption • Non-authenticated encryption unsafe • IKEv2 w/rekey button • Manual keying w/management • Policy management needed - ? • Cipher suites follow algorithms blue book • Compression (IPComp)

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