• Hierarchical Identity-Based Encryption with Tight Multi-challenge Security 

      Langrehr, Roman; Pan, Jiaxin (Peer reviewed; Journal article, 2020)
      We construct the first hierarchical identity-based encryption (HIBE) scheme with tight adaptive security in the multi-challenge setting, where adversaries are allowed to ask for ciphertexts for multiple adaptively chosen ...
    • Shorter QA-NIZK and SPS with Tighter Security 

      Abe, Masayuki; Jutla, Charanjit; Ohkubo, Miyako; Pan, Jiaxin; Roy, Arnab; Wang, Yuyu (Chapter, 2019)
      Quasi-adaptive non-interactive zero-knowledge proof (QA-NIZK) systems and structure-preserving signature (SPS) schemes are two powerful tools for constructing practical pairing-based cryptographic schemes. Their efficiency ...
    • Signatures with Tight Multi-user Security from Search Assumptions 

      Pan, Jiaxin; Ringerud, Magnus (Peer reviewed; Journal article, 2020)
      We construct two tightly secure signature schemes based on the computational Diffie-Hellman (CDH) and factoring assumptions in the random oracle model. Our schemes are proven secure in the multi-user setting, and their ...
    • Signed Diffie-Hellman Key Exchange with Tight Security 

      Pan, Jiaxin; Qian, Chen; Ringerud, Magnus (Peer reviewed; Journal article, 2021)
      We propose the first tight security proof for the ordinary two-message signed Diffie-Hellman key exchange protocol in the random oracle model. Our proof is based on the strong computational Diffie-Hellman assumption and ...
    • Tightly Secure Hierarchical Identity-Based Encryption 

      Langrehr, Roman; Pan, Jiaxin (Peer reviewed; Journal article, 2020)
      We construct the first tightly secure hierarchical identity-based encryption (HIBE) scheme based on standard assumptions, which solves an open problem from Blazy, Kiltz, and Pan (CRYPTO 2014). At the core of our constructions ...
    • Unbounded HIBE with Tight Security 

      Langrehr, Roman; Pan, Jiaxin (Peer reviewed; Journal article, 2020)
      We propose the first tightly secure and unbounded hierarchical identity-based encryption (HIBE) scheme based on standard assumptions. Our main technical contribution is a novel proof strategy that allows us to tightly ...