Identity Theft Prevention using Aggregated Proof of Knowledge by qvs59240

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									Identity Theft Prevention using
Aggregated Proof of
Knowledge
Elisa Bertino,
Abhilasha Bhargav-Spantzel,
Anna Squicciarini,
Rui Xue
What is Identity Theft?
   Identity Theft is the use of personally identifying
    information belonging to one individual by
    another individual for financial or personal gain.

    Technical           Pharming, Network Sniffing,
                        Database Attacks, Password
                        Cracking
    Physical            Dumpster Diving, Trusted
                        Insiders, Theft and Loss
    Social              Phishing, Legal Identity Sources
    Engineering
Multi-Factor Identity Verification
Require additional identity information as proof
to qualify to be the owner of the identity attribute
being used.
Example Real Life Scenario: Requirement for additional proofs of identity


     I will use
     my credit                                          To use your
      card to                                            credit card
        pay                                             please show
                                                        your drivers
                                                      license and an
                                                     additional photo
                                                     id for verification
                                                      of your identity
Overview of our Approach
    We have a logical entity called the registrar
     which establishes and maintains identity
     commitments used to establish proof of
     knowledge of strong identifiers used later for
     multifactor identity verification.
    Two main Phases:
1.   Enrollment or Registration: User commits his strong
     identifiers to be used later as proofs of identity.
2.   Usage: Before revealing the actual value of a required
     attribute one has to verify the commitments of other
     attributes as proofs of identity.
Example
                      CCN Issuer
      2.
      COMMIT_CCN           1. Request Certificate                                                       4. Check for
         38763                                                                                          duplicates (38763)
                                                                                                              5. Create IdR
                                                   3. Request registration:                                                    Alice@Reg1
                                                    COMMIT_CCN               + “Alice, Jones”                     CCN SIG1 COM1
                                                                                                                                      Alice
                                                       38763                                                                          Jones
                                                        6. Success Registration
                                                                                                              12. Check for duplicates (46523)
                                                   11. Request registration:                                  13. Update IdR
                ate




                      Alice                                                  + “Alice, Jones”                                  Alice@Reg1
              ific




                                                    COMMIT_SSN
                                                       46523
           ert




                                                                                                                                     Alice
                                                                                                                  CCN SIG1 COM1
                                                                                                                                     Jones
           tc




                                                   14. Success Registration                     Registrar: Reg1                      Alice
      es




                                                                                                                  SSN   SIG2 COM2
             COMMIT_SSN                                                                                                              Jones
      qu




                46523
  Re




                                    8.                                                                  17. Send CCN’s validity status
       .
 9.
      10




                                         Re
                                              qu
                                                   ire
                                                         CC
                                    7.                         N
 SSN Issuer                              Re
                                              qu
                                                                   +S
                                                   es                   SN
                                                        ts                   pro                                                    16. Identity
                                                             erv                   of                                               Verification is done
                               1                   i ce
                           pro 5. Pr                                                                                                successfully if the
                                       o
                          a n o f o f vi d e                                                                                        proof is valid
                             d S kn                                                               Service Provider : SP-Shop
                                 SN o w 1 ) a g
                                     ), 2 led gre
                                             g
                                   an ) sho e of gate
                                       dI
                                         dR w of (CCN
                                                CC
                                                   N
Preliminary
Concepts

{
Example of ZK Proof system
Pedersen Commitment – ZK Prove
know how to open
    Public commitment c = gxhr (mod p)
    Private knowledge x,r
    Protocol:
1.   P: picks random y, s in [1..q], sends d = gyhs
     mod p
2.   V: sends random challenge e in [1..q]
3.   P: sends u=y+ex, v=s+er (mod q)
4.   4. V: accepts if guhv = dce (mod p)
Bilinear Maps
   Let G1, G2, and Gt be cyclic groups of the
    same order.




Bilinear maps are called pairings because they associate pairs of elements
from G1 and G2 with elements in Gt.
Aggregated signatures (Boneh, et al.)
   Signatures on different messages by multiple signers can be
    combined into one small signature.
   Scheme requires bilinear map (in Gap DH groups)
   BGLS Details:
Preliminary
Concepts

}
Proving aggregated signature on
       committed values
   To prove the knowledge of multiple identifiers.
Proving aggregated signature on
committed values and open
      To open in clear multiple sensitive identifiers.
Proving aggregated signature on some
committed values and opening some
           To prove u values and open v
 Integrating the zero-knowledge
    proof into the verification
          To prove the knowledge of secret commitments.




Note that the only information sent by the principal
is σ, while in the previous protocol the tags and the
commitments were also sent.
        Zero-knowledge proof the
          aggregated signature
                 To prove the possession of signature.




The final submitted value is independent of any of the actual
signatures.
Principal remains unlinkable and anonymous even if it had
initially revealed its strong identifiers and commitments to the
verifying SP.
 Efficiency Analysis
• Our signatures on commitments are short and the storage complexity is
smaller than the ones computed with existing techniques [Camenisch et.
Al.’04]

• Our approach is more flexible in that whenever n messages are
committed for a user, the user is able to to prove 2n-1 many combinations
of them which does not appear possible in the existing schemes




    Comparison of the number of exponentiations for proving t factors
Conclusion
   Identity theft is a
    major problem
   Our approach
    supports the strong
    verification of identity
    attributes, which is a
    component of
    comprehensive
    solutions against
    identity theft

								
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