Integrating Identity based Cryptosystem IBC with CGA in Mobile IPv6 draftcaomipshopibccga00'txt

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Integrating Identity based Cryptosystem (IBC)
with CGA in Mobile IPv6draft-cao-mipshop-ibc-cga-
00.txt

• Zhen Cao
• Hui Deng
• IETF 67

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Outline

• Issues with CGA-based drafts
• Issues with address ownership problem
• On our draft IBC-CGA

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Problem with CGA-based draftsQuote from RFC
3972 Section 7.4

• A strong cautionary note has to be made about
  using CGA for purpose other than SEND
• Each protocol MUST define its own type tag
  values as explained to defend against related
  protocol attacks
• The minimum RSA key length of 384 bits may be
  too short for many applications and the impact of
  key compromise on the particular protocol must be
  evaluated more considerations are necessary
• If the goal is not to verify claims about IPv6
  addresses, CGA signatures are probably not the
  right solution not a sufficient security
  mechanism

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Several attacks to CGA
n public key length H hash extension provided
by CGA
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Address ownership problem

• By signing a message with a private key, the CGA
  verifier asserts that
• (a) the address is owned by somebody
• (b) the message is coming from the address owner
• It cannot tell whether the address owner is a
  trusted party. How to address this trust
  relationship problem is an issue.

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What is IBC ?

• Identity Based Cryptosystem a cryptosystem in
  which the public key is retrieved from an
  identity of the entity, and the private key is
  securely distributed by the Key Distribution
  Center.
• K F (pub, ID), pub is publicly known
• K- F (sec, ID), sec is known only to KDC and
  the client
• Is not new to IETF

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What is IBC-CGA ?

• Using IBC to broke trust relations through a
  trusted third party (e.g. Key Distribution
  Center)
• IBC-CGA
• MN registers IBC-ID on KDC, get K and K-
• Get CGA CGA F (K)
• Signature CGA-Sign (K-, M)
• IBC-CGA parameter containing an IBC-ID instead
  of a public key
• Trust by verifying the CGA signature, the
  verifier can convince whether the sender is an
  entity trusted by the KDC as well as address
  ownership

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Comparison
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Acknowledgement

• Discussion with Christian Vogt, James Kempf,
  Wassim Haddad in the ML, thanks for your comments
  and advice.

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Thanks for your attention

• Questions ?