International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Collusion Resistant Broadcast and Trace from Positional Witness Encryption

Rishab Goyal
Satyanarayana Vusirikala
Brent Waters
DOI: 10.1007/978-3-030-17259-6_1
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Conference: PKC 2019
Abstract: An emerging trend is for researchers to identify cryptography primitives for which feasibility was first established under obfuscation and then move the realization to a different setting. In this work we explore a new such avenue—to move obfuscation-based cryptography to the assumption of (positional) witness encryption. Our goal is to develop techniques and tools, which we will dub “witness encryption friendly” primitives and use these to develop a methodology for building advanced cryptography from positional witness encryption.We take a bottom up approach and pursue our general agenda by attacking the specific problem of building collusion-resistant broadcast systems with tracing from positional witness encryption. We achieve a system where the size of ciphertexts, public key and private key are polynomial in the security parameter $$\lambda $$ and independent of the number of users N in the broadcast system. Currently, systems with such parameters are only known from indistinguishability obfuscation.
  title={Collusion Resistant Broadcast and Trace from Positional Witness Encryption},
  booktitle={Public-Key Cryptography – PKC 2019},
  series={Lecture Notes in Computer Science},
  author={Rishab Goyal and Satyanarayana Vusirikala and Brent Waters},