DTN Security Update

1
DTN Security Update

• Stephen Farrell, Trinity College Dublin
• Susan Symmington, The MITRE Corp.
• Howard Weiss, Sparta Inc.
• IETF-65
• Dallas
• March 2006

2
Document status

• DTN Security Overview
• draft-irtf-dtnrg-sec-overview-01
• Wont cover today unless
• Bundle Security Protocol Specification
• draft-irtf-dtnrg-bundle-security-01
• Comments to dtn-sec_at_mailman.dtnrg.org or to
  dtn-interest_at_dtnrg.org (usual subscription rules)

3
Bundle security changes

• Aligned terminology with Bundle Protocol spec.
• Allow security headers to follow the payload, so
  nodes with small buffers can validate the
  security results in large bundles
• Add a new field to the headers to correlate
  front/rear pairs
• Ciphersuite ID is in front header security
  result in rear
• Increased the bits for indicating the
  ciphersuite
• Accommodated and use SDNVs
• Removed the discussion of bundle service API
  primitives and parameters (as in Bundle spec.)

4
Bundle security (quickly)

• Header types (BAH, PSH, CH 2,3,4) and mandated
  use of canonical bundle header format
• Canonicalization for putting bundles with BAHs
  and PSHs in the correct form for security result
  calculation and verification
• Strict and mutable c14n algs
• Needs checking typical place to go wrong.
• Three mandatory ciphersuites (one each for BAH,
  PSH, and CH)
• BAH-HMAC
• PSH-RSA-SHA256
• CH-RSA-AES-PAYLOAD-PSH

5
Big Open Issue - Combinations

• Question is really how much flexibility to allow
  in terms of combining PSH and CH
• Example 1 order of application
• Node1 adds PSH (signs)
• Node2 adds CH (encrypts)
• Node3 verifies PSH (strips?)
• Node4 removes CH (decrypts)
• Example 2 super encryption
• Its hard to get this right and the current draft
  probably doesnt
• And things get complex very quickly
• Guidance?

6
Other open issues

• Providing confidentiality for source,
  destination, and possibly other header fields
• Key Management (lack of a delay-tolerant method)
• Research topic really
• Handling Replays
• Some replays are desirable how distinguish them?
• Deleting recently seen messages is impractical
  in a DTN context
• Traffic Analysis
• Not clear if there is a need for hiding traffic,
  but perhaps
• Current known methods of doing so consume
  significant resources
• Routing Protocol Security
• Security Policy Distribution
• Multicast Security

7
Implementation

• Itd be really nice to get someone coding this
  stuff up
• Any takers?

8
Plans

• Receive and incorporate comments on the two
  drafts
• Security overview document may be ready to go to
  (informational) RFC as is
• Bundle Security Protocol may need additional
  ciphersuites to handle more complex combinations
  of applying PSH/CH services please make your
  preferences known
• Goal submit both security specs into the RFC
  process by summer