Risky Traitor Tracing and New Differential Privacy Negative Results - - PowerPoint PPT Presentation

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risky traitor tracing and new differential privacy
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Risky Traitor Tracing and New Differential Privacy Negative Results - - PowerPoint PPT Presentation

May 07, 2023 435 likes •650 views

Risky Traitor Tracing and New Differential Privacy Negative Results Rishab Goyal Venkata Koppula Andrew Russell Brent Waters Hardness of Non-Interactive Differential Privacy from One-Way Functions Lucas Kowalczyk Tal Malkin Jonathan

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Risky Traitor Tracing and New Differential Privacy Negative Results

Rishab Goyal Venkata Koppula Andrew Russell Brent Waters

Hardness of Non-Interactive Differential Privacy from One-Way Functions

Lucas Kowalczyk Tal Malkin Jonathan Ullman Daniel Wichs

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Risky Traitor Tracing and New Differential Privacy Negative Results Differential Privacy Negative Results

Rishab Goyal Venkata Koppula Andrew Russell Brent Waters

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Traitor Tracing [Chor-Fiat-Naor 94]

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Key Challenges: (1) Obfuscated Decoder (2) Collusions

Decoder

Find Traitors

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Tracing Algorithms

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(1) No false trace: (2) Catch:

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It’s About the Ciphertext Size!

PKE: Bilinear Maps [Boneh-Sahai-Waters06,Boneh-Waters06…]: Functional Encryption/iO[GGHRSW13,Boneh-Zhandry14]:

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Can we get better efficiency from standard assumptions if we relax tracing requirement?

(* Subsequent to this work, G-Koppula-Waters gave an LWE-based standard TT scheme matching FE/iO-based efficiency.)

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(1) No false trace: (2) Catch:

Relaxing Tracing

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(1) No false trace: (2) Catch:

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(Main) Results [G-Koppula-Russell-Waters]

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Remaining Talk

Part I: Risky Traitor Tracing Part II: Differential Privacy Negative

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Part II: Differential Privacy Negative Results (Luke)

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  • Persistent decoder setting

– Periodic key refreshes, decoder must work across cycles – Catching probability can be amplified

Standalone Risky TT Applications

  • Resource constrained settings

– Get best possible tracing w/ 10 KB ciphertext overhead

  • Risk averse attackers

– Deterrence against attackers if traitors heavily penalized – Heavy penalty vs. Low catching probability

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Framework for Risky TT – Mixed Bit Matching Encryption

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Mixed Bit Matching Security

Security: 3 properties PK/SK CT Hiding  Distinguish

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CT Hiding  Key Hiding  Distinguish Distinguish

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Transformation to Risky TT

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Transformation to Risky TT

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Transformation to Risky TT

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Transformation to Risky TT

Check if decoder is correct

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is correct

Do this poly times

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Transformation to Risky TT

Successful decryption probability

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  • Security proof of the transformation

– Significantly departs from existing proof techniques for TT

  • Building Mixed Bit Matching Encryption from Bilinear

Missing Pieces and Other Results

  • Building Mixed Bit Matching Encryption from Bilinear

Maps

  • Generic risky amplification

– Improving success probability of tracing

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Remaining Talk

Part I: Building Risky Traitor Tracing Part II: Differential Privacy Negative

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Part II: Differential Privacy Negative Results (Luke)

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