1 / 21

BiTR: Built-in Tamper Resilience

BiTR: Built-in Tamper Resilience. Seung Geol Choi (U. Maryland). Joint work with Aggelos Kiayias (U. Connecticut) Tal Malkin (Columbia U.). Motivation. Traditional cryptography internal state: inaccessible to the adversary. In reality Adv may access/affect the internal state

lottie
Download Presentation

BiTR: Built-in Tamper Resilience

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. BiTR: Built-in Tamper Resilience Seung Geol Choi (U. Maryland) Joint work with Aggelos Kiayias (U. Connecticut) Tal Malkin (Columbia U.)

  2. Motivation • Traditional cryptography • internal state: inaccessible to the adversary. • In reality • Adv may access/affect the internal state • E.g., leaking, tampering • Solution? • Make better hardware • Or, make better cryptography

  3. In this work • Focus on tampering hardware tokens • In the universal composability framework

  4. Modeling Tamper-Resilient Tokensin UC

  5. Tamper-Proof Tokens [Katz07] • Ideal functionality Create ! Forge Run …. Run

  6. Tamperable Tokens • Introduce new functionality Create ! Forge Run Tamper

  7. Built-in Tamper Resilience (BiTR) • M is -BiTR • In any environment w/ M deployed as a token, tampering gives no advantage: s.t. indistinguishable

  8. Questions • Are there BiTR tokens? • Yes, with affine tamperings. • UC computation from tamperable tokens? • Generic UC computation from tamper-proof tokens [Katz07] • Yes, with affine tamperings.

  9. Affine Tampering • Adversary can apply an affine transformation on private data.

  10. Schnorr Identification

  11. Schnorr-token is affine BiTR

  12. UC-secure Computation with Tamperable Tokens

  13. Commitment Functionality • Complete for general UC computation. m ! open m

  14. DPG-commitment • DPG: dual-mode parameter generation using hardware tokens • Normal mode • Parameter is unconditionally hiding • Extraction mode • The scheme becomes extractable commitment.

  15. DPG-Commitment from DDH • Parameter: • Com(b) = • Extraction Mode • DH tuple with • Trapdoor r allows extraction • Normal Mode • Random tuple • Com is unconditionally hiding.

  16. Realizing Fmcom from tokens • DPG-Parameter: (pS, pR) • S obtains pR, by running R’s token. • R obtains pS, by running S’s token. • exchange pS and pR • Commit: (Com(m), dpgCompS(m), π) • π: WI (same msg) or (pR from ext mode) • Reveal: (m, π‘) • π': WI (Com(m)) or (pR: ext mode)

  17. UC-security of the scheme • The scheme • Commit: (Com(m), dpgCompS(m), π) • π: WI (same msg) or (pR from ext mode) • Reveal: (m, π‘) • π': WI (Com(m)) or (pR: ext mode) • S*: Make the pS extractable and extract m. • R*: Make the pR extractable and equivocate.

  18. DPG from tamperable tokens • [Katz07] showed DPG-commitment • Unfortunately, the token description is not BiTR. • Our approach: Modify Katz’s scheme to be BiTR.

  19. BiTR DPG

  20. BiTR DPG • The protocol is affine BiTR • Similar to the case of Schnorr • Compose with a BiTR signature • Okamato signature [Oka06] • In this case, the composition works.

  21. Summary • BiTR security • Affine BiTR protocols • UC computation from tokens tamperable w/ affine functions • In the paper • Composition of BiTR tokens • BiTR from deterministic non-malleable codes

More Related