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[Author] Ren ISHIBASHI(2hit)

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  • Post-Quantum Anonymous One-Sided Authenticated Key Exchange without Random Oracles

    Ren ISHIBASHI  Kazuki YONEYAMA  

     
    PAPER-Cryptography and Information Security

      Pubricized:
    2023/03/13
      Vol:
    E106-A No:9
      Page(s):
    1141-1163

    Authenticated Key Exchange (AKE) is a cryptographic protocol to share a common session key among multiple parties. Usually, PKI-based AKE schemes are designed to guarantee secrecy of the session key and mutual authentication. However, in practice, there are many cases where mutual authentication is undesirable such as in anonymous networks like Tor and Riffle, or difficult to achieve due to the certificate management at the user level such as the Internet. Goldberg et al. formulated a model of anonymous one-sided AKE which guarantees the anonymity of the client by allowing only the client to authenticate the server, and proposed a concrete scheme. However, existing anonymous one-sided AKE schemes are only known to be secure in the random oracle model. In this paper, we propose generic constructions of anonymous one-sided AKE in the random oracle model and in the standard model, respectively. Our constructions allow us to construct the first post-quantum anonymous one-sided AKE scheme from isogenies in the standard model.

  • Adaptive-ID Secure Hierarchical ID-Based Authenticated Key Exchange under Standard Assumptions without Random Oracles

    Ren ISHIBASHI  Kazuki YONEYAMA  

     
    PAPER-Cryptography and Information Security

      Pubricized:
    2022/03/24
      Vol:
    E105-A No:9
      Page(s):
    1252-1269

    Hierarchical ID-based authenticated key exchange (HID-AKE) is a cryptographic protocol to establish a common session key between parties with authentication based on their IDs with the hierarchical delegation of key generation functionality. All existing HID-AKE schemes are selective ID secure, and the only known standard model scheme relies on a non-standard assumption such as the q-type assumption. In this paper, we propose a generic construction of HID-AKE that is adaptive ID secure in the HID-eCK model (maximal-exposure-resilient security model) without random oracles. One of the concrete instantiations of our generic construction achieves the first adaptive ID secure HID-AKE scheme under the (standard) k-lin assumption in the standard model. Furthermore, it has the advantage that the computational complexity of pairing and exponentiation operations and the communication complexity do not depend on the depth of the hierarchy. Also, the other concrete instantiation achieves the first HID-AKE scheme based on lattices (i.e., post-quantum).